Milk powder production equipment. Powdered milk production line

The idea of producing milk powder as a business can be quite tempting. We’ll tell you what equipment is required for this and offer feedback from experienced entrepreneurs. Today this direction is considered quite promising and profitable even when opening a small plant.

Food production activities are highly profitable forms of business. After all, all people without exception need nutrition every day. For an enterprising businessman, the difference is only in the choice of the final product for consumers.

Relevance of the issue

Powdered milk is used in various industries:

For creating infant formulas.
In expensive cosmetics.
In order to restore milk and its derivatives in regions where, for objective reasons, cow breeding is impossible.
When feeding young animals in livestock farming.
In the preparation of confectionery, bakery products and various semi-finished products.
For canning.
As a dietary supplement.
When creating special mixtures for sports nutrition, etc.

It is surprising that such a sought-after product is becoming increasingly scarce in our country. Although it was Russia that only a few decades ago occupied a leading position in its production and export. Setting up such a line is quite simple and relatively inexpensive, but the profits promise to be high. Today there is almost no competition in this area of activity, and demand significantly exceeds supply.

To understand how profitable it is to engage in powdered milk as a business, it is enough to find out the average sales value. So, in our country they are willing to pay no less than 7,000 rubles for a ton of products. If you set up production for the purpose of export, then for the same amount of milk powder you can earn from 3,000 to 5,000 dollars.

An attractive point is the win-win nature of such a business. After all, even if powdered milk cannot be sold for some reason, this equipment can be used for the production of other equally popular goods - egg mass, blood serum, formed elements, broths, various extracts, hydrolysers, etc.

Required documents

An LLC is considered a more convenient form of business registration. To do this, contact the tax service and create a legal entity. You will need to submit the following list of papers:

statement;
receipt of payment of state duty;
company charter;
agreement on the establishment of a company;
confirmation of ownership of the premises;
or a letter of guarantee from the building's landlord.

In this case, a suitable taxation system is selected, most often UTII, and the activity code OKVED 10.51 is indicated - and dairy products (except raw). You will also have to obtain a license from Rospotrebnadzor to manufacture this type of product.

Since the food industry is very strictly controlled by the sanitary and epidemiological service, it is advisable to familiarize yourself with their requirements for the arrangement of the premises, hygiene standards, as well as the standards for the quality of the finished product. All this will be checked regularly. Each batch of goods must comply with the prescribed standards in GOSTs.

Preparing the premises

You won’t be able to make powdered milk with your own hands in the kitchen. At the very least, for industrial scale and compliance with all quality characteristics of the finished product, it will be necessary to set up a separate workshop. A room measuring 25-30 square meters is suitable for this. m. But if you immediately decide to engage in large-scale production and purchase equipment capable of producing up to 5 tons of powdered milk per day, then you will have to find a building with an area of at least 110 square meters. m.

In any case, you need to prepare it in a certain way. The workshop must meet the following parameters:

Tiled floors and walls at a height of 2.5 meters.
Plumbing supplying warm and cold water.
Heating provided.
Installed forced ventilation system.
The electrical network must withstand an industrial load of 380 V.
Good lighting, distributed evenly throughout the area.

All surfaces must be thoroughly wet cleaned and disinfected daily. Monitor the cleanliness of the premises, as SES representatives will often visit the workshop and check such parameters. Don’t forget about fire safety, for which you will have to comply with GPI standards.

Equipment purchase

For entrepreneurs in this area, there is a fairly wide selection of suitable equipment. You can purchase a whole monoblock with a ready-made system for the entire production cycle, or create an automated line based on individual units. Typically the following elements are required:

High pressure pump;
drying chamber;
electric or steam heater;
storage bunker;
sifter;
packaging line;
recuperator;
cyclone;
fan;
screw conveyor;
crystallization plant.

You will also have to purchase a sufficient set of containers, additional lighting fixtures, control systems for various parameters, etc. In order to save money, you can pay attention to domestic manufacturers of this equipment. But a lot depends on your goals. It is important to focus on the quality of the equipment and its power. The cost of a finished line can range from 1 million rubles to several tens.

Production technology

The entire process of turning regular milk into a dry product can be described as follows:

Preparation and cleaning - the raw material is slightly heated, which makes it easier to bring it to the required parameters of fat content and density. At the same time, it is passed through many filters to remove excess impurities and cells.
Normalization - in this case, the desired parameters are achieved, and thanks to the separator, the cream is separated and the milk is skimmed if necessary.
Pasteurization - due to which the raw materials are completely disinfected, all harmful bacteria are destroyed in it. This can happen in three different ways - long (at 65 degrees), short (at 90°) or instant (98°).
Cooling - this process takes place in a storage tank where the milk is cooled to low temperatures.
Thickening - what is an evaporation plant used for? In it, under the influence of vacuum, the raw material is thickened to 40-45% of the dry matter.
Homogenization - achieve uniformity of the resulting mass.
Drying – by spraying in a special chamber, a dry concentration is achieved.
Sifting and packaging is the last stage of production at which the product receives its finished appearance.

The usual raw product is used as the main substance to create milk powder. You can order it at any farm where cows are kept or from private owners. For the business to be profitable, it is advisable to create such a plant near livestock farms and cowsheds. At the same time, you will not have to pay for the delivery of raw materials from distant regions.

Staff

If you start producing milk powder at a large enterprise, you will need about 10-15 employees to maintain the technological process. But for a small workshop, a few people are enough:

technologist;
ordinary workers;
cleaners;
accountant;
driver.

Sales of products

Since the demand for milk powder is quite high, and existing factories provide only 54% of it, it will remain to make itself known in the market so that buyers will line up. To do this, you can use any available advertising - in the media, the Internet, classifieds, or establish personal contacts with the owners of large enterprises where this product is required.

You can deliver goods directly:

To the confectionery shop.
To bakeries.
Dairies located away from farms.
Northern regions.
Retail grocery chains, etc.

Financial calculations

When opening a small workshop for the production of milk powder, you can get by with an investment of 1-1.5 million rubles. At the same time, the sale of finished products at a cost of 7,000 rubles per ton and a productivity level of 300 kg per day for a year of operation will bring a profit of about 756,000. Therefore, in 2-3 years, the initial investment will fully pay off.

If we talk about a larger-scale business, then we should focus on the following figures:

With a production capacity of 5 tons of goods per day, an annual profit of 12.6 million rubles can be achieved. If we organize the export of products, then income will increase significantly. But even at minimum prices, you can count on a return on capital investments within 5-6 years.

The profitability of this production does not fall below 30-40%. And if you add other options for creating goods to the business plan, then the payback of the project will come much earlier.

Video: your own business in the production of milk powder.

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Ministry of Education and Science of the Russian Federation

Federal Agency for Education

GOU VPO "Magnitogorsk State Technical University"

Them. G.I. Nosov"

Department of Standardization, Certification and Food Technology

Course work

on the topic: “Technology for the production of skimmed milk powder”

Completed:

Gurevich O.V., TSP-06

Checked:

Maksimova G.K.

Magnitogorsk 2010

Introduction

1. General information

2. Technology for the production of skimmed milk powder

2.1 Requirements for raw materials for the production of skimmed milk powder

2.2 Characteristics of the technological process for the production of skimmed milk powder

3. Product calculation

4. Requirements for the quality and safety of skimmed milk powder

5. Defects of skimmed milk powder

6. Confirmation of conformity of skimmed milk powder

Conclusion

List of sources used

Introduction

An analysis of available statistical materials shows that the dairy industry in most countries is developing steadily. From 1996 to 2001, world production of cow's milk increased by 5.3%, reaching 501 million tons in 2002.

The fastest growing sector of the dairy market is the production of yoghurts and cheeses, as well as various desserts, curd products and products with biological and fruit additives.

Consumption of dairy products in 2003 amounted to 227 kg. with the recommended consumption rate by the Institute of Nutrition of the Russian Academy of Medical Sciences - 390 kg per person per year.

Production of skimmed milk powder, whole milk substitute and whey powder for two months of 2010 increased by 5.5% to 21.89 thousand tons, dry whole milk, dry cream and mixtures - by 41.4% to 4.068 thousand tons. Powdered milk is used for the production of confectionery and candy products, and since this area is developing very quickly, skimmed milk powder factories are constantly increasing production volumes and introducing new technologies. One skim milk powder plant can process 50-60 tons of raw materials per shift, which then produces approximately 2.5 tons of skim milk. And the by-product is oil.

The scope of application of skimmed milk powder is very extensive: baby food, confectionery industry, ice cream, flavors, stabilizers, thickeners and other food additives, bakery industry, fat and oil industry and production of combined oils, alcohol industry, processed cheeses, cottage cheese, drinks, semi-finished products, soups, snacks, creams, sauces, complex products, dry mixes, etc. In this regard, in this course work we will consider the production of skim milk powder.

1 . General information

Canned milk -- These are products made from natural milk using condensation (followed by sterilization or adding sugar) and drying. They have a high energy value due to the concentration of milk components in them. In addition, canned milk is characterized by good transportability and significant shelf life.

Canning -- This is the processing of products in special ways in order to protect them from spoilage. Of all the known principles of canning, two are used for the production of canned milk: abiosis and anabiosis.

Canning according to the principle abiosis based on the complete destruction of microorganisms in the product (sterilization). Canning based on the principle of suspended animation consists of suppressing microbiological processes by physical means: increasing osmotic pressure (osmoanabiosis) and drying (xeroanabiosis).

Canning drying based on removing moisture from the product and creating physiological dryness, causing an increase in the difference between the osmotic pressure in the bacterial cell and the environmental pressure. For the normal course of processes associated with the vital activity of microorganisms, it is necessary that the mass fraction of water in the product is about 25...30%. Therefore, if the amount of moisture in the product is below the minimum required for the life of microorganisms, the shelf life of the product will increase. The mass fraction of moisture in milk powder is 3...4%; at the same time, the concentration of substances dissolved in water greatly increases and conditions are created that bring microorganisms into an anabiotic state. To prevent the development of residual microflora, the dried product must be protected from moisture absorption. The product should be stored in a hermetically sealed container at relatively low temperatures (not higher than 10°C), which inhibit the occurrence of biochemical reactions. Dry milk products are obtained through canning and drying.

Powdered milk products are powders made from agglomerated milk particles of different shapes and sizes, depending on the type of product and drying method. The range of dry dairy products is very diverse. The main types of dry milk products produced by the dairy industry are presented in Table 1.1.

Table 1.1 -- Main types of dry dairy products

Product name	Mass fraction fat content,%
Powdered cow's milk


Dry cream
Dry high fat cream
Homemade powdered milk
Skimmed milk powder
Powdered milk Smolensk
Instant whole milk powder
Dry fermented milk products





Powdered buttermilk
Powdered milk with vegetable fat
Powdered milk with hydrogenated fat
Powdered milk with malt extract

Powdered milk - powdered food product obtained by drying pre-condensed milk. Powdered milk was first produced in 1802 in Russia by the head physician of the Nerchinsk factories, Osip Krichevsky. The first information about the production of milk powder in Europe dates back to 1885. industrial production - began at the end of the 19th century.

Powdered milk happens whole(SCM) or low fat(COM). These two types of milk powder differ in the percentage of substances they contain (Table 1.2). WITH ear whole milk- a dry milk product, the mass fraction of milk solids in which is no less than 95%, the mass fraction of protein in the skimmed milk solids is no less than 34% and the mass fraction of fat is no less than 20%. Skimmed milk powder- a dry milk product, the mass fraction of milk solids in which is no less than 95%, the mass fraction of protein in the skim milk solids is no less than 34% and the mass fraction of fat is no more than 1.5%.

Table 1.2 -- Content of substances in SCM and COM

Instant milk powder is produced by mixing whole and skim milk powder. The mixture is moistened with steam, after which it sticks together into lumps, which are then dried again.

2. Skimmed milk powder production technology

2.1 Requirements for raw materials for the production of skimmed milk powder

For the production of skim milk powder, natural cow's milk is used - raw materials of at least second grade according to GOST R 52054-2003 “Cow's milk - raw. Technical specifications" without any feed taste or smell, with an acidity of no more than 18°T.

Natural cow's milk - raw materials: Milk without extracts and additions of dairy and non-dairy components, subjected to primary processing (cleaned from mechanical impurities and cooled to a temperature of (4 ± 2) 0 C after milking) and intended for further processing. skimmed fermented milk

The basic all-Russian norm for the mass fraction of milk fat is 3.4%, the basic norm for the mass fraction of protein is 3.0%.

Milk is obtained from healthy animals in farms free from infectious diseases, in accordance with Veterinary legislation. The quality of milk must meet the requirements of GOST R 52054-2003 “Cow's milk - raw. Technical conditions" and Federal Law No. 88-FZ "Technical regulations for milk and dairy products". It is not allowed to use milk for the manufacture of a product that has not passed a veterinary and sanitary examination and does not have veterinary accompanying documents in the established form.

In terms of organoleptic indicators, milk must meet the requirements specified in Table 2.1.

In terms of physical and chemical indicators, milk must meet the requirements specified in Table 2.2.

Indicators of microbiological safety and the content of somatic cells of cow's raw milk should not exceed the permissible level established in Table 2.3 to Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products”.

Table 2.1 - Organoleptic characteristics of raw milk

Indicator name	Norm for milk variety

Consistency	Homogeneous liquid without sediment or flakes. Freezing is not allowed
Taste and smell	Clean, without foreign odors and tastes not characteristic of fresh natural milk
		A mild feed taste and smell is allowed in the winter-spring period.
	White to light cream

Table 2.2 - Physico-chemical parameters of raw milk

Table 2.3 - Indicators of microbiological safety and somatic cell content of cow's raw milk

Indicators of chemical and radiological safety of cow's raw milk should not exceed the permissible level established by Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products”.

Periodic tests are carried out according to safety indicators (content of toxic elements, mycotoxins, antibiotics, pesticides, radionuclides; microbiological indicators) in accordance with the production control program developed by the manufacturer and approved in the prescribed manner.

2.2 Characteristics of the technological process for the production of skimmed milk powder

The technological process for producing skim milk powder consists of the following technological operations: acceptance and preparation of raw materials, normalization, separation, pasteurization, thickening, homogenization, drying, dry product cooling, packaging and storage.

Reception and incoming control of raw milk. When accepting milk at enterprises, the quantity by weight and quality by organoleptic, physico-chemical indicators are determined in accordance with the requirements of GOST R 52054-2003 “Cow's milk - raw. Technical conditions" and Federal Law No. 88-FZ "Technical regulations for milk and dairy products".

When accepting milk, the organoleptic indicators, temperature, density, mass fraction of fat, acidity and efficiency of heat treatment are determined in each batch, and the mass fraction of protein, bacterial contamination and rennet fermentation test - at least once a decade.

Milk purification. During the weighing process, to remove mechanical impurities, the milk is filtered, passed through a cloth, and then sent for further purification. For cleaning, filters of different systems are used, where cotton pads, gauze, synthetic materials, metal meshes, etc. are used as working elements.

Currently, downstream enterprises are equipped with milk separators, in which mechanical impurities are removed under the influence of centrifugal force. Centrifugal purification in them is carried out due to the difference between the densities of milk plasma particles and foreign impurities. Foreign impurities, having a higher density than milk plasma, are thrown towards the drum wall and settle on it in the form of mucus. Traditionally, in technological lines, centrifugal milk purification is carried out at 35-40 0 C, since under these conditions, more effective sedimentation of mechanical impurities occurs due to an increase in the speed of particle movement. During centrifugal milk purification, a significant portion of microorganisms are removed along with mechanical impurities, which is explained by the difference in their physical properties.

Separation- this is the division of milk into two fractions of different densities: high-fat (cream) and low-fat (skimmed milk). The separation process is carried out under the influence of centrifugal force in the separator drum. The optimal separation temperature is 35-45°C. Heating the milk to this temperature ensures good skimming.

Pasteurization of milk - This is the heat treatment of milk in order to destroy vegetative forms of microflora, including pathogenic ones. The pasteurization regime should also ensure that the desired properties of the finished product are obtained, in particular organoleptic characteristics (give taste, desired viscosity, curd density).

The effect of pasteurization, determined by the degree of death of pathogenic microflora, influences the choice of modes and methods of pasteurization. Of the pathogenic microorganisms, tuberculosis bacteria are more resistant to heat treatment. Since the work of identifying the causative agents of tuberculosis is complex, the effectiveness of pasteurization is usually determined by the death of no less persistent E. coli. When producing skim milk powder, it is recommended to use instant pasteurization (at a temperature of 85-87°C or 95-98°C without holding).

Thickening. After cooling, the milk is sent for condensation, i.e. concentration of milk solids or its mixture with components by evaporating moisture in vacuum evaporation units at pressure below atmospheric. The use of vacuum allows you to reduce the boiling point of milk and preserve its properties to the greatest extent.

To thicken milk, multi-effect vacuum evaporation units operating on the falling film principle or circulation units are used.

In the continuous flow method, continuous evaporation is carried out. The mixture, partially condensed in the first housing, sequentially passes through the remaining housings, where it is evaporated to the final concentration of dry substances, enters the product container and is cooled.

Compared to the batch method, the continuous-flow method reduces the time spent on processing 1 ton of milk by 1.36 times, the consumption of steam by 1.55 times and water by 1.46 times. In addition, the continuous-flow method allows you to automate the technological process.

When evaporating, the main parameters of the process are temperature, duration of exposure and concentration ratio. The evaporation temperature, depending on the number of installation bodies and the content of dry substances in the mixture, varies from 45°C to 82°C. In a film vacuum evaporation unit, the evaporation time ranges from 3 minutes to 15 minutes. When condensing, the composition of canned milk can be determined in accordance with the multiplicity of concentration (or thickening). The concentration factor shows how many times the mass fractions of the dry residue and its components increase or how many times the mass of the condensed product decreases compared to the mass of the original raw material.

Homogenization - This is a milk processing process that involves crushing (dispersing) fat globules by subjecting the milk to significant external forces.

The intensity of the homogenization process increases with increasing temperature, since the fat becomes completely liquid and the viscosity of the product decreases. As the temperature rises, the sedimentation of fat also decreases. At temperatures below 50°C, the settling of fat increases, which leads to a deterioration in the quality of the product. The most preferable homogenization temperature is 60-65°C. At excessively high temperatures, whey proteins in the homogenizer may precipitate.

With increasing pressure, the mechanical effect on the product increases, the dispersion of fat increases, and the average diameter of fat globules decreases. According to VNIKMI, at a pressure of 15 MPa, the average diameter of fat globules is 1.43 μm, and the homogenization efficiency is 74%. As the fat and solids content of the product increases, a lower homogenization pressure should be used, due to the need to reduce energy costs.

The need to homogenize condensed milk is due to the fact that during mechanical, heat treatment and thickening, the fat fraction of milk is destabilized (release of free fat), which contributes to fat oxidation and spoilage of the product during storage. Therefore, to increase stability and reduce free fat content, milk is homogenized. Homogenization is carried out at a temperature of 50-60°C and a pressure of 10-15 MPa for a one-stage homogenizer. After homogenization, the condensed milk enters an intermediate container and then is dried.

Drying. In dry skim milk, the mass fraction of fat is no more than 1.5% and moisture no more than 4-7%. Based on the composition of powdered milk, we can conclude that it is not absolutely dry, it contains so-called irremovable moisture. As the product dries, the moisture remaining in the product is retained more and more firmly in it due to increased adhesive forces and increased resistance to water movement. Therefore, the product can only be dried to an equilibrium moisture content corresponding to the relative humidity and temperature of the drying agent.

With the spray method, drying is carried out as a result of contact of the sprayed condensed product with hot air. Condensed milk is sprayed into the drying chamber using disc and nozzle sprayers. In disk sprayers, condensed milk is sprayed under the action of the centrifugal force of a rotating disk, from the nozzle of which the milk comes out at a speed of 150-160 m/s and is crushed into tiny droplets due to air resistance. Condensed milk is supplied to the nozzle sprayers under high pressure (up to 24.5 MPa).

When drying with spray dryers, condensed milk is sprayed into the top of the dryer, where hot air is supplied. Hot air, mixing with the smallest drops of milk, gives them part of the heat, under the influence of which the moisture evaporates and the milk particles quickly dry. The high rate of drying (evaporation) is due to the large contact surface of fine milk with hot air. With the rapid evaporation of moisture, the air is cooled to 75-95°C, so the thermal effect on the product is insignificant and its solubility is high. The dried milk in powder form settles to the bottom of the drying tower.

Spray dryers, depending on the movement of air and milk particles, are divided into three types: direct-flow, in which the movement of air and milk is parallel; countercurrent, in which the movement of milk and air particles is opposite; mixed - with mixed movement of air and milk particles.

The most rational and progressive are high-performance direct-flow spray dryers, in which the degree of solubility of milk powder reaches 96-98%.

In accordance with the technical characteristics of spray dryers, the following drying modes must be observed: the temperature of the air entering the direct-flow type drying unit should be 165-180°C, and at the exit from the drying tower - 65-85°C. Upon leaving the drying tower, skimmed milk powder is sifted on a shaking sieve and sent for cooling.

Packaging, labeling, storage. Dry milk products are packaged in sealed consumer and transport containers. Consumer packaging includes metal cans with a solid or removable lid and a net weight of 250, 500 and 1000 grams; combined cans with a removable lid, having a net weight of 250, 400 and 500 grams with an internal hermetically sealed bag made of aluminum foil, paper and other materials; glued packs with cellophane inserts with a net weight of 250 grams. Unimpregnated four- and five-layer paper bags are used as transport containers; cardboard stuffing drums; plywood-stamped barrels with polyethylene liner bags with a net weight of 20-30 kg.

Powdered milk in consumer containers (except for glued packs with cellophane liners) and transport containers with polyethylene liners is stored at a temperature of 0 to 10 ° C and a relative air humidity of no more than 85% for no more than 8 months from the date of production. Powdered milk in glued packs with cellophane liners and stamped plywood barrels with cellophane and parchment liners is stored at a temperature from 0°C to 20°C and a relative air humidity of no more than 75% for no more than 3 months from the date of production.

The marking of consumer packaging, its contents, place and method of application must be in accordance with GOST R51074. The marking of the transport container in which the product is directly packaged must comply with GOST 23561. The marking of the group packaging and transport container in which the product is packaged in consumer packaging must comply with GOST 23651.

The prepared milk is purified using a centrifugal milk separator, then normalized and pasteurized under the conditions described above. After pasteurization, the milk is supplied for condensation to a three-stage vacuum evaporation unit operating on the falling film principle. Milk condensed to a dry matter mass fraction of 43-52% is homogenized and sent to an intermediate container equipped with a stirrer and a heating jacket. From the intermediate container, condensed milk is pumped into the drying chamber. Moreover, it must have a temperature of at least 40 °C.

Cooling of powdered milk is carried out with air in a pneumatic transport system. The cooled dry product from the intermediate storage bin is transported for packaging.

3 . Product calculation

The enterprise receives milk in the amount of 50 tons with a fat mass fraction (mf) of 3.5%.

After separation, we obtain skim milk with m.d.z. 0.05% and cream with m.d.z. 35%. Let us determine the amount of skim milk and cream after separation without taking into account the norms of permissible losses.

The amount of cream with a known amount of separated milk is determined by formula (3.1):

where C l is the amount of cream;

Based on this, we obtain the following amount of cream, which will be sent for further processing to the butter shop:

The amount of skim milk with a known amount of separated milk is determined by formula (3.2):

where M o is the amount of skim milk;

M - amount of whole milk;

Fm, Fl, F o - fat content of whole milk, cream and skim milk, respectively.

Thus, we get the following amount of skim milk:

We check the correctness of the calculations using the fat balance equation (formula (3.3)) of the mixture:

where F m, F sl, F o - fat content of whole milk, cream and skim milk, respectively;

M, M sl, M o - the amount of whole milk, cream and skim milk, respectively.

Let us present the results obtained in Table 3.1.

Table 3.1 - Summary table of receipt and consumption of raw materials

When condensing, the composition of canned milk can be determined in accordance with the frequency of concentration or thickening. The concentration factor shows how many times the mass fractions of the dry residue and its components increase or how many times the mass of the condensed product decreases compared to the mass of the original raw material. The concentration factor is calculated from the following ratios (3.4):

Where n - multiplicity of concentration (thickening);

m cm, m etc- mass of the initial mixture and product;

WITH etc, AND CR, SOMO etc - mass fraction of dry substances, fat, dry skimmed milk residue in the product and, accordingly, in the initial mixture ( WITH cm, AND cm, SOMO cm).

In our case, the initial mixture is skim milk with a mass fraction of dry substances of 8.9%, and the product is condensed milk with a mass fraction of dry substances of 46% (according to regulatory documents 46-50%). Based on these data, the condensation factor is equal to:

Knowing the multiplicity of condensation, we can determine the mass of the condensed product using formula (3.5):

During the production process of COM, condensed milk with a mass fraction of dry substances of 46% is dried to powdered milk with a mass fraction of dry substances of 95%. Based on this, knowing the mass of condensed milk (15021.46 kg), we can determine the mass of skimmed milk powder:

9012.9 kg - Xkg;

Let's present the calculations in a summary table (Table 3.2).

Table 3.1 - Summary table for product calculations

Thus, from 50 tons of milk received by the enterprise, with a mass fraction of fat content of 3.5%, we obtain 5 tons of cream with a mass fraction of fat content of 35%, which are sent to the butter shop, and 4 tons of COM with a mass fraction of fat content of 0.3%.

4 . Requirements for the quality and safety of skimmed milk powder

Skimmed milk powder is produced in accordance with the requirements of GOST R 52791-2007 “Canned milk products. Powdered milk. Technical conditions" according to technological instructions approved in the prescribed manner.

In terms of organoleptic indicators, skimmed milk powder must meet the requirements presented in Table 4.1.

Table 4.1 - Organoleptic characteristics of skimmed milk powder

The determination of organoleptic indicators of COM is carried out in accordance with GOST 29245--91 “Canned milk products. Methods for determining physical and organoleptic indicators."

In terms of physical and chemical indicators, skimmed milk powder must comply with the standards specified in Table 4.2.

Table 4.2 - Physico-chemical parameters of skimmed milk powder

Indicator name	Norm for COM
Moisture content. %, no more, for a product packaged: In consumer packaging; In a transport container.
Mass fraction of fat, %	No more than 1.5
Mass fraction of protein in dry skimmed milk residue, %. no less
Solubility index, cm 3 wet sediment, no more, for a product packaged: In consumer packaging In transport container
Cleanliness group, not lower
Acidity, 0 T (% lactic acid)	From 16 to 21 inclusive (from 0.144 to 0.189 inclusive)

Determination of the mass fraction of moisture COM is carried out in accordance with GOST 29246--91 “Canned dry milk. Methods for determining moisture."

Determination of the mass fraction of COM fat is carried out in accordance with GOST 29247--91 “Canned milk products. Methods for determining fat."

Determination of the acidity of COM is carried out in accordance with GOST 30305.3--95 “Canned condensed milk and dry milk products. Titrimetric methods for performing acidity measurements."

The determination of the COM solubility index is carried out in accordance with GOST 30305.4--95 “Canned dry milk. Methodology for performing measurements of the solubility index."

Determination of lead, cadmium and mercury content is carried out according to GOST R 51301-99 “Food products and food raw materials. Stripping voltammetric methods for determining the content of toxic elements”, according to GOST 30178-96 “Raw materials and food products. Atomic absorption method for determining toxic elements."

Table 4.3 - Permissible levels of hazardous substances in skimmed milk powder

Determination of pesticide content - according to GOST 23452-79 “Milk and dairy products. Methods for determining residual amounts of organochlorine pesticides.”

In terms of microbiological indicators, skimmed milk powder must comply with the requirements of Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products”. These requirements are indicated in Table 4.4.

Determination of QMAFAnM in COM is carried out according to GOST 10444.15-94 “Food products. Methods for determining the number of mesophilic aerobic and facultative anaerobic microorganisms.”

Table 4.4 - Content of microorganisms in skimmed milk powder

Determination of bacteria of the genus Salmonella in COM is carried out according to GOST R 52814--2007 (ISO 6579:2002) “Food products. Method for identifying bacteria of the genus Salmonella."

Determination of coliforms in COM is carried out according to GOST R 52816--2007 “Food products. Methods for identifying and determining the number of coliform bacteria (coliform bacteria).”

Determination of the content of Staphylococcus aureus in COM is carried out according to GOST 30347--97 “Milk and dairy products. Methods for determining Staphylococcus aureus."

Determination of yeast and mold fungi - according to GOST 10444.12-88 “Food products. Method for determination of yeasts and molds."

5 . Vicesskimmed milk powder

Depending on the nature of the physical and chemical changes in the components of milk during the manufacturing and storage process, certain defects may appear in the products.

Reduced solubility dry milk products is observed with severe denaturation of whey proteins during the drying process. The defect also occurs when storing a product with an increased content of free fat, which transfers to the surface of dry particles and reduces wettability. The release of free fat is facilitated by the increased moisture content in the product (more than 7%). Moisture causes lactose to crystallize while destabilizing the fat. Increased humidity of dry dairy products, as well as storage in non-hermetically sealed packaging, leads to a decrease in solubility due to protein denaturation and the formation of poorly soluble melanoidins. Proteins denature in the presence of free moisture in products (bound moisture does not change the colloidal properties of the protein). In this regard, the moisture content in milk powder should not exceed 4-5%.

Darkening of canned milk occurs when a large number of melanoidins are formed as a result of the reaction between the amino groups of proteins and the aldehyde group of lactose and glucose. The defect is formed as a result of long-term storage of dry dairy products in non-airtight containers (in conditions of high humidity). The formation of melanoidins in milk powder is accompanied by darkening of the product, the appearance of an unpleasant specific taste and odor, and a decrease in solubility. To prevent darkening of powdered milk, it is necessary to comply with the requirements for moisture content (4-5%) and packaging tightness. Rancid taste is caused by the hydrolysis of fat under the action of lipase remaining after pasteurization. Found in spray-dried milk powders.

6 . Conformity confirmation of skimmed milk powder

Milk and its processed products sold on the territory of the Russian Federation are subject to mandatory confirmation of compliance with the requirements of Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products” (hereinafter referred to as Federal Law No. 88) in the form of acceptance declaration about conformity (hereinafter referred to as declaration of conformity) or mandatory certification according to the schemes established by Federal Law No. 88. Voluntary confirmation compliance with the requirements of national standards, organizational standards, codes of practice, voluntary certification systems and the terms of contracts for milk and its processed products, the processes of their production, storage, transportation, sale and disposal is carried out at the initiative of the applicant in the form of voluntary certification. The applicant has the right to choose the form of confirmation of conformity and the scheme for confirming conformity provided for milk and products of its processing by Federal Law No. 88.

Skimmed milk powder has a long shelf life (more than 30 days), therefore, in accordance with the requirements of Federal Law No. 88, confirmation of compliance with COM is carried out in the form of a declaration of conformity using scheme 3d, 4d, 5d or 7d, or in the form of mandatory certification using scheme 3c, 4s, 5s or 6s.

Declaration of conformity milk and its processed products is carried out by accepting a declaration of conformity on the basis of one’s own evidence and (or) on the basis of evidence obtained with the participation of a certification body and (or) an accredited testing laboratory (center) (hereinafter referred to as a third party). When declaring the conformity of mass-produced milk processing products, the validity period of such a declaration of conformity is no more than five years. To confirm compliance of the COM with the requirements of Federal Law No. 88, the following schemes for declaring conformity are used:

1) 3D- declaration of conformity of milk or products of its processing based on positive results of studies (tests) of standard samples of these products obtained with the participation of a third party, and a certificate of the quality system at the production stage of these products;

2) 4d- declaration of conformity of milk or products of its processing based on positive results of studies (tests) of standard samples of these products obtained with the participation of a third party, and a certificate of the quality system at the stage of control and testing of these products;

3) 5d- declaration of conformity of a batch of milk or its processed products based on positive research (test) results obtained through a representative sampling of samples from a batch of these products with the participation of a third party;

4) 7d- declaration of conformity of milk or products of its processing based on the positive results of studies (tests) of standard samples of these products, carried out on their own or with the involvement of other organizations on behalf of the applicant, and a certificate of the quality system at the stage of design and production of these products.

The applicant accepts the declaration of conformity and registers it in the manner prescribed by the legislation of the Russian Federation. The applicant shall mark the COM for which the declaration of conformity has been accepted with the mark of circulation on the market.

Mandatory certification milk processing products are carried out by a product certification body, the scope of accreditation of which extends to food products, including milk processing products, on the basis of an agreement between the applicant and the product certification body according to the schemes established by Federal Law No. 88.

A certificate of conformity for mass-produced milk processing products is issued for a period determined by the certification body depending on the state of production of these products and the stability of their quality, but not more than three years. To confirm compliance of COM with the requirements of Federal Law No. 88, the following mandatory certification schemes are applied:

1) 3s- certification of mass-produced milk processing products based on positive test results of standard samples obtained with the participation of an accredited testing laboratory (center), with subsequent control by the product certification body of certified milk processing products;

2) 4s- certification of mass-produced milk processing products based on positive test results of standard samples obtained with the participation of an accredited testing laboratory (center), and analysis of the state of production of these products with subsequent monitoring by the product certification body of certified milk processing products and, if necessary, the state of their production;

3) 5s- certification of mass-produced milk processing products based on positive test results of standard samples of these products obtained with the participation of an accredited testing laboratory (center), and certification of the applicant’s quality management system with subsequent control by the product certification body of certified milk processing products and body for certification of quality management systems for the certified quality management system of the applicant;

4) 6s- certification of a batch of milk processing products based on positive research (test) results of a representative sample of samples of these products obtained with the participation of an accredited testing laboratory (center).

The applicant, having received a certificate of conformity for COM, marks it with a mark of circulation on the market. The applicant, when producing and selling SOM, takes the necessary measures to ensure its compliance with the requirements of Federal Law No. 88.

Conclusion

Modern industrial milk processing is a complex complex of sequentially performed interconnected chemical, physicochemical, microbiological, biochemical, biotechnological, thermophysical and other labor-intensive and specific technological processes. These processes are aimed at producing dairy products containing either all or part of the components of milk. The production of canned milk involves preserving all the solids in milk after removing moisture from it.

Dairy industry enterprises are equipped with a large number of processing equipment. Rational operation of technological equipment requires in-depth knowledge of its features and design features. When using modern technological equipment, it is important to preserve to the maximum extent the nutritional and biological value of the raw material components in the produced dairy products.

The desire of manufacturers to improve organoleptic properties, ensure the safety and profitability of products, and maintain the original brand name leads to changes in traditional production methods, rationalization of composition, production of combined dairy products with the addition of non-dairy components and the use of various food additives. Moreover, economic feasibility does not always correspond to the quality indicators, nutritional and biological value of the finished product. Thus, an increase in the timing of the sale of dairy products leads to a loss of their biological value. In this regard, an urgent task in the dairy industry is to preserve traditional methods of producing high-quality dairy products.

List of sources used

1. Federal Law No. 88-FZ Technical regulations for milk and dairy products [Text]. - Entered 2008-06-12.

2. GOST R 52791-2007. Canned milk. Powdered milk. Specifications [Text]. - Enter. 2007-12-19. - M.: Gosstandart of Russia: IPK Standards Publishing House, 2007. - 8 p.

3. GOST R 52054-2003. Cow's milk is raw. Specifications [Text]. - Enter. 2004-01-01. - M.: Gosstandart of Russia: IPK Standards Publishing House, 2004. - 12 p.

4. Bredikhin S.A. Technology and technology of milk processing [Text] - M.: Kolos, 2003. - 400 p. - ISBN 5-9532-0081-1.

5. Krus, G.N. Technology of milk and dairy products [Text]/ Khramtsov A.G., Volokitina Z.V., Karpychev S.V. - M.: KolosS, 2006. - 455 p. - ISBN 5-9532-0166-4.

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Single stage drying

Single-stage drying is a spray drying process in which the product is dried to a final residual moisture content in a spray dryer chamber, see Figure 1. The theory of droplet formation and evaporation in the first drying period is the same for both single-stage and two-stage drying and is outlined here.

The initial speed of droplets falling from the rotary atomizer is approximately 150 m/s. The main drying process occurs while the drop is slowed down by friction with the air. Drops with a diameter of 100 microns have a braking path of 1 m, and drops with a diameter of 10 microns have only a few centimeters. The main decrease in the temperature of the drying air, caused by the evaporation of water from the concentrate, occurs during this period.

Enormous heat and mass transfer occurs between particles and the surrounding airin a very short time, so the quality of the product may suffer greatly if those factors that contribute to the deterioration of the product are left unattended.

When water is removed from the droplets, a significant decrease in the mass, volume and diameter of the particle occurs. Under ideal drying conditions, droplet mass from a rotary atomizer
decreases by approximately 50%, volume by 40%, and diameter by 75%. (see Figure 2).

However, the ideal technique for creating droplets and drying has not yet been developed. Some amount of air is always included in the concentrate when it is pumped from the evaporator and especially when the concentrate is supplied to the feed tank due to splashing.

But even when spraying the concentrate with a rotary atomizer, a lot of air is included in the product, since the atomizer disk acts as a fan and sucks in air. The inclusion of air in the concentrate can be counteracted by using specially designed discs. On a disk with curved blades (the so-called disk of high bulk density), see Figure 3, the air, under the influence of the same centrifugal force, is partially separated from the concentrate, and in a disk washed by steam, see Figure 4, the problem is partially solved by the fact that Instead of liquid-air contact, there is liquid-vapor contact. It is believed that when spraying with nozzles, air is not included in the concentrate or is included to a very small extent. However, it turns out that some air is included in the concentrate early in the atomization process, outside and inside the spray pattern due to friction between the liquid and the air before droplets are formed. The higher the nozzle output (kg/h), the more air enters the concentrate.

The ability of a concentrate to incorporate air (i.e. foaming ability) depends on its composition, temperature and dry matter content. It turned out that the concentrate with a low solids content has significant foaming ability, which increases with temperature. Concentrate with a high solids content foams significantly less, which is especially noticeable as the temperature increases, see Figure 5. Generally speaking, whole milk concentrate foams less than skim milk concentrate.

Thus, the air content in droplets (in the form of microscopic bubbles) largely determines the decrease in droplet volume during drying. Another, even more important factor is the ambient temperature. As already noted, intense exchange of heat and water vapor occurs between the drying air and the drop.

Therefore, a temperature and concentration gradient is created around the particle, so that the whole process becomes complex and not entirely clear. Drops of pure water (100% water activity) evaporate when in contact with high-temperature air, maintaining the wet-bulb temperature until the very end of evaporation. On the other hand, products containing dry matter at extreme drying (i.e. when water activity approaches zero) are heated at the end of drying to the ambient air temperature, which in relation to a spray dryer means the outlet air temperature. (see Figure 6).

Therefore, a concentration gradient exists not only from the center to the surface, but also between points on the surface, as a result, different parts of the surface have different temperatures. The larger the particle diameter, the greater the overall gradient, since this means a smaller relative surface area. Therefore, small particles dry more quickly
evenly.

During drying, the solids content naturally increases due to the removal of water, and both viscosity and surface tension increase. This means that the diffusion coefficient, i.e. the time and zone of diffusion transfer of water and steam becomes smaller, and due to the slowdown in the evaporation rate, overheating occurs. In extreme cases, so-called surface hardening occurs, i.e. formation of a hard crust on the surface through which water and steam or absorbed air diffuse
So slow. In the case of surface hardening, the residual moisture of the particle is 10-30%; at this stage, proteins, especially casein, are very sensitive to heat and easily denature, resulting in a poorly soluble powder. In addition, amorphous lactose becomes solid and almost impermeable to water vapor, so that the temperature of the particle increases even more when the rate of evaporation, i.e. the diffusion coefficient approaches zero.

Because water vapor and air bubbles remain inside the particles, they become overheated, and if the ambient air temperature is high enough, the vapor and air expand. The pressure in the particle increases, and it swells into a ball with a smooth surface, see Figure 7. Such a particle contains many vacuoles, see Figure 8. If the ambient temperature is high enough, the particle may even explode, but if this does not happen, the particle still has a very thin crust, about 1 micron, and will not withstand mechanical processing in the cyclone or conveying system, so it will leave the dryer with the exhaust air. (see Figure 9).

If there are few air bubbles in the particle, then the expansion, even with overheating, will not be too strong. However, overheating as a result of surface hardening degrades the quality of casein, which reduces the solubility of the powder.

If the ambient temperature, i.e. If the temperature at the outlet of the dryer is maintained low, the particle temperature will also be low.

The outlet temperature is determined by many factors, the main of which are:

moisture content of the finished powder
temperature and humidity of drying air
dry matter content in concentrate
spraying
concentrate viscosity

Moisture content of the finished powder

The first and most important factor is the moisture content of the finished powder. The lower the residual humidity must be, the lower the required outlet relative humidity, which means higher air and particle temperatures.

Temperature and humidity of drying air

The moisture content of the powder is directly related to the humidity of the outlet air, and increasing the air supply to the chamber will lead to a slightly larger increase in the output air flow rate, since due to increased evaporation there will be more moisture in the air. The moisture content of the drying air also plays an important role, and if it is high, it is necessary to increase the outlet air temperature to compensate for the additional moisture.

Dry matter content in concentrate

An increase in solids content will require a higher outlet temperature because evaporation is slower (the average diffusion coefficient is lower) and requires a larger temperature difference (driving force) between the particle and the surrounding air.

Spraying

Improving atomization and creating a more finely dispersed aerosol allows you to reduce the outlet temperature, because the relative surface area of the particles increases. Because of this, evaporation occurs more easily and the driving force can be reduced.

Concentrate viscosity

Atomization depends on viscosity. Viscosity increases with increasing protein content, crystalline lactose and total solids content. Heating the concentrate (be aware of thickening as it ages) and increasing the spray disc speed or nozzle pressure can solve this problem.

The overall drying efficiency is expressed by the following approximate formula:

where: T i - inlet air temperature; T o - outlet air temperature; T a - ambient temperature

Obviously, to increase the efficiency of spray drying, it is necessary to either increase the ambient temperature, i.e. preheat the extracted air, for example, with condensate from an evaporator, or increase the inlet air temperature, or lower the outlet temperature.

Dependence ζ on temperature is a good indicator of the dryer's operating efficiency, since the outlet temperature is determined by the residual moisture content of the product, which must meet a certain standard. A high outlet temperature means that the drying air is not being used optimally, for example due to poor atomization, poor air distribution, high viscosity, etc.

For a normal spray dryer processing skim milk (T i = 200°C, T o = 95°C),ζ ≈ 0.56.

The drying technology discussed so far refers to a plant with a pneumatic conveying and cooling system, in which the product discharged from the bottom of the chamber is dried to the required moisture content. At this stage, the powder is warm and consists of cohesive particles, very loosely bound into large loose agglomerates formed during primary agglomeration in the spray plume, where particles of different diameters have different velocities and therefore collide. However, when passing through the pneumatic transport system, the agglomerates are subjected to mechanical stress and crumble into individual particles. This type of powder, (see Figure 10), can be characterized as follows:

individual particles
high bulk density
dusting if it is skimmed milk powder
not instant

Two-stage drying

The particle temperature is determined by the ambient air temperature (outlet temperature). Since bound moisture is difficult to remove by traditional drying, the outlet temperature must be high enough to provide driving force (Δ t, i.e. temperature difference between the particle and the air) capable of removing residual moisture. Very often this degrades the quality of the particles, as discussed above.

It is therefore not surprising that a completely different drying technology was developed, designed to evaporate the last 2-10% of moisture from such particles.

Since evaporation at this stage is very slow due to the low diffusion coefficient, the equipment for post-drying must be such that the powder remains in it for a long time. This drying can be carried out in a pneumatic conveying system, using hot conveying air to increase the driving force of the process.

However, since the speed in the transport channel must be≈ 20 m/s, for effective drying a channel of considerable length will be required. Another system is the so-called “hot chamber” with a tangential entrance to increase the holding time. Once drying is complete, the powder is separated in a cyclone and sent to another pneumatic conveying system with cold or dried air, where the powder is cooled. After separation in the cyclone, the powder is ready for packaging in bags.

Another additional drying system is the VIBRO-FLUIDIZER device, i.e. a large horizontal chamber divided by a perforated plate welded to the body into upper and lower sections. (Figure 11). For drying and subsequent cooling, warm and cold air is supplied to the distribution chambers of the device and evenly distributed over the working area by a special perforated plate, BUBBLE PLATE.

This provides the following benefits:

The air is directed downward towards the surface of the plate, so particles move along the plate, which has sparse but large holes and can therefore operate for a long time without cleaning. In addition, it releases powder very well.
The unique manufacturing method prevents the formation of cracks. Therefore, BUBBLE PLATE meets strict sanitary requirements and is USDA approved.

The size and shape of the holes and the air flow rate are determined by the air velocity required to fluidize the powder, which in turn is determined by the properties of the powder, such as moisture content and thermoplasticity.

The temperature is determined by the required evaporation. The size of the holes is chosen so that the air speed ensures fluidization of the powder on the plate. The air speed should not be too high so that the agglomerates are not destroyed by abrasion. However, it is not possible (and sometimes not desirable) to avoid the entrainment of some (especially small) particles from the fluidized bed with the air. Therefore, the air must pass through a cyclone or bag filter, where the particles are separated and returned to the process.

This new equipment allows you to carefully evaporate the last percent of moisture from the powder. But this means that the spray dryer can be operated in a manner different from that described above, in which the powder leaving the chamber has the moisture content of the finished product.

The advantages of two-stage drying can be summarized as follows:

higher output per kg of drying air
increased efficiency
best product quality:

good solubility
high bulk density
low free fat content
low absorbed air content

Less powder emissions

The fluidized bed can be either a piston-type vibrating fluidized bed (VibroFluidizer) or a fixed back-mix fluidized bed.

Two-stage drying in the Vibro-Fluidizer(piston flow)

In the Vibro-Fluidizer, the entire fluidized bed vibrates. The perforations in the plate are made so that the drying air is directed along with the flow of powder. ForTo ensure that the perforated plate does not vibrate at its own frequency, it is mounted on special supports. (see Figure 12).

Figure 12 - Spray dryer with Vibro-Fluidizer for two-stage drying

The spray dryer operates at a lower outlet temperature, resulting in higher moisture content and lower particle temperature. The wet powder is discharged by gravity from the drying chamber into the Vibro-Fluidizer.

There is, however, a limit to lowering the temperature, since due to the increased humidity the powder becomes sticky even at lower temperatures and forms lumps and deposits in the chamber.

Typically, the use of a Vibro-Fluidizer can reduce the outlet temperature by 10-15 °C. This results in much gentler drying, especially at the critical stage of the process (30 to 10% humidity), the drying of the particles (see Figure 13) is not interrupted by surface hardening, so that the drying conditions are close to optimal. The lower particle temperature is partly due to the lower ambient temperature, but also to the higher moisture content, so that the particle temperature is close to the wet bulb temperature. This naturally has a positive effect on the solubility of the finished powder.

A decrease in outlet temperature means a higher efficiency of the drying chamber due to an increaseΔ t. Very often, drying is carried out at a higher temperature and at a higher solids content in the raw material, which further increases the efficiency of the dryer. In this case, of course, the outlet temperature also increases, but the increased moisture content reduces the temperature of the particles, so that overheating and surface hardening of the particles do not occur.

Experience shows that drying temperatures can reach 250 °C or even 275 °C when drying skim milk, which raises the drying efficiency to 0.75.

Particles reaching the bottom of the chamber have higher humidity and lower temperature than with traditional drying. From the bottom of the chamber, the powder flows directly into the drying section of the Vibro-Fluidizer and is immediately liquefied. Any holding or transportation will cause the warm, moist thermoplastic particles to stick together and form hard-to-break clumps. This would reduce the drying efficiency of the Vibro-Fluidizer and some of the finished powder would have too high a moisture content, i.e. the quality of the product would suffer.

Only the powder from the drying chamber flows into the Vibro-Fluidizer by gravity. Fines from the main cyclone and from the cyclone serving the Vibro-Fluidizer (or from a washable bag filter) are fed into the Vibro-Fluidizer by a transport system.

Since this fraction is a smaller particle size than the powder from the drying chamber, the moisture content of the particles is lower and they do not require the same degree of secondary drying. Very often they are quite dry, however, they are usually fed into the last third of the drying section of the Vibro-Fluidizer to ensure the required moisture content of the product.

The cyclone powder discharge point cannot always be located directly above the Vibro-Fluidizer so that the powder flows into the drying section by gravity. Therefore, a pressure pneumatic conveying system is often used to move powder. The pressure pneumatic conveying system makes it easy to deliver powder to any part of the installation, since the transport line is usually represented by a 3 or 4 inch milk pipe. The system consists of a low-flow, high-pressure blower and a blow-off valve, and collects and transports the powder, see Figure 14. The amount of air is small relative to the amount of powder conveyed (only 1/5).

A small portion of this powder is again airborne from the Vibro-Fluidizer and then transported from the cyclone back to the Vibro-Fluidizer. Therefore, unless special devices are provided, when the dryer is stopped, a certain time is required to stop such circulation.

For example, a distribution valve can be installed in the transfer line that will direct the powder to the very last part of the Vibro-Fluidizer, where it will be discharged in a few minutes.

At the final stage, the powder is sifted and packed into bags. Since the powder may contain primary agglomerates, it is recommended that it be conveyed to the hopper via another pressure pneumatic conveying system to increase the bulk density.

It is well known that when water evaporates from milk, energy consumption per kg of evaporated water increases as the residual moisture approaches zero. (Figure 15).

Drying efficiency depends on the air inlet and outlet temperatures.

If the steam consumption in the evaporator is 0.10-0.20 kg per kg of evaporated water, then in a traditional single-stage spray dryer it is 2.0-2.5 kg per kg of evaporated water, i.e. 20 times higher than in an evaporator. Therefore, attempts have always been made to increase the dry matter content of the evaporated product. This means that the evaporator will remove a higher proportion of water and energy consumption will be reduced.

Of course, this will slightly increase the energy consumption per kg of water evaporated in the spray dryer, but the overall energy consumption will be reduced.

The above steam consumption per kg of evaporated water is an average figure, since the steam consumption at the beginning of the process is much lower than at the end of drying. Calculations show that to obtain a powder with a moisture content of 3.5%, 1595 kcal/kg of powder is required, and to obtain a powder with a moisture content of 6%, only 1250 kcal/kg of powder is required. In other words, the last stage of evaporation requires approximately 23 kg of steam per kg of water evaporated.

The table illustrates these calculations. The first column reflects the operating conditions in a traditional plant, where the powder from the drying chamber is conveyed to the cyclones by a pneumatic conveying and cooling system. The next column reflects the operating conditions in a two-stage dryer in which drying from 6 to 3.5% moisture is carried out in a Vibro-Fluidizer. The third column represents two-stage drying at high inlet temperature.

From the indicators marked *), we find: 1595 – 1250 = 345 kcal/kg of powder

Evaporation per kg of powder is: 0.025 kg (6% - 3.5% + 2.5%)

This means that the energy consumption per kg of evaporated water is: 345/0.025 = 13.800 kcal/kg, which corresponds to 23 kg of heating steam per kg of evaporated water.

In the Vibro-Fluidizer, the average steam consumption is 4 kg per kg of evaporated water; naturally, it depends on the temperature and flow of drying air. Even if the steam consumption of a Vibro-Fluidizer is twice as high as a spray dryer, the energy consumption to evaporate the same amount of water is still much lower (since the product processing time is 8-10 minutes, and not 0-25 seconds, as in spray dryer). And at the same time, the productivity of such an installation is greater, the quality of the product is higher, powder emissions are lower, and the functionality is wider.

Two-stage fixed fluid bed drying (back-mix)

To improve drying efficiency, the air temperature at the outlet To during two-stage drying is reduced to the level at which the powder with a moisture content of 5-7% becomes sticky and begins to settle on the walls of the chamber.

However, the creation of a fluidized bed in the conical part of the chamber provides further improvement in the process. Air for secondary drying is supplied to a chamber under a perforated plate, through which it is distributed over the powder layer. This type of dryer can operate in a mode in which the primary particles dry to a humidity of 8-12%, which corresponds to an outlet air temperature of 65-70 °C. Such utilization of drying air makes it possible to significantly reduce the size of the installation with the same dryer performance.

Powdered milk has always been considered difficult to fluidize. However, a special patented plate design, see Figure 17, ensures that the air and powder move in the same direction as the primary drying air. This plate, provided the bed height and fluidization start speed are correctly selected, allows you to create a static fluidized bed for any product made from milk.

Static fluidized bed (SFB) devices are available in three configurations:

with annular fluidized bed (Compact dryers)
with circulating fluidized bed (MSD dryers)
with a combination of such layers (IFD dryers)

Annular fluidized bed (Compact dryers)

An annular reverse-mix fluidized bed is located at the bottom of the cone of a traditional drying chamber around a central exhaust air exhaust pipe. Thus, there are no parts in the conical part of the chamber that interfere with the air flow, and this, together with the jets emerging from the fluidized bed, prevents the formation of deposits on the walls of the cone, even when processing sticky powders with a high moisture content. The cylindrical part of the chamber is protected from deposits by a wall blowing system: a small amount of air is tangentially supplied at high speed through specially designed nozzles in the same direction in which the primary drying air is swirled.

Due to the rotation of the air-dust mixture and the cyclone effect that occurs in the chamber, only a small amount of powder is carried away by the exhaust air. Therefore, the proportion of powder entering the cyclone or washable bag filter, as well as powder emissions into the atmosphere, is reduced for this type of dryer.

Powder is continuously discharged from the fluidized bed by flowing through an adjustable height baffle, thereby maintaining a certain level of the fluidized bed.

Due to the low outlet air temperature, the drying efficiency is significantly increased compared to traditional two-stage drying, see table.

After leaving the drying chamber, the powder can be cooled in a pneumatic conveying system, see Figure 20. The resulting powder consists of individual particles and has the same or better bulk density than that obtained by two-stage drying.

P Products containing fat should be cooled in a vibrating fluidized bed, in which the powder is simultaneously agglomerated. In this case, the fines fraction is returned from the cyclone to the atomizer for agglomeration. (see Figure 21).

Circulating fluidized bed (MSD dryers)

To further improve drying efficiency without creating problems with deposit build-up, a completely new spray dryer concept has been developed - the MultiStage Dryer, MSD.

In this apparatus, drying is performed in three stages, each of which is adapted to the characteristic moisture content of the product. At the pre-drying stage, the concentrate is sprayed with direct-flow nozzles located in the hot air channel.

Air is supplied vertically into the dryer at high speed through an air distributor, which ensures optimal mixing of the droplets with the drying air. As already noted, in this case evaporation occurs instantly while the droplets move vertically down through a specially designed drying chamber. The moisture content of the particles is reduced to 6-15%, depending on the type of product. At such high humidity, the powder has high thermoplasticity and stickiness. The air entering at high speed creates the Venturi effect, i.e. sucks in the surrounding air and carries small particles into a moist cloud near the sprayer. This leads to “spontaneous secondary agglomeration”. The air coming from below has sufficient speed to fluidize the layer of settled particles, and its temperature provides the second stage of drying. The air leaving this fluidized back-mixing bed, together with the exhaust air of the first drying stage, exits the chamber from above and is fed into the primary cyclone. From this cyclone, the powder is returned to the backmix fluidized bed and air is supplied to the secondary cyclone for final cleaning.

When the moisture content of the powder is reduced to a certain level, it is discharged through the rotary valve into the Vibro-Fluidizer for final drying and subsequent cooling.

Drying and cooling air from the Vibro-Fluidizer passes through a cyclone where the powder is separated. This fine powder is returned to the atomizer, chamber cone (static fluidized bed) or Vibro-Fluidizer. In modern dryers, cyclones are replaced by bag filters with SIP.

The installation produces a coarse powder, which is due to “spontaneous secondary agglomeration” in the atomizer cloud, where dry fine particles constantly rising from below stick to semi-dry particles, forming agglomerates. The agglomeration process continues when the atomized particles come into contact with the fluidized bed particles. (see Figure 22).

Such a plant can be operated at very high air inlet temperatures (220-275 °C) and extremely short contact times, nevertheless achieving good powder solubility. This installation is very compact, which reduces the requirements for room size. This, as well as the reduced operating cost due to the higher inlet temperature (10-15% less compared to traditional two-stage drying), makes this solution very attractive, especially for agglomerated products.

Figure 22 - Multi-stage spray dryer (MSD)

Spray drying with integrated filters and fluidized beds (IFD)

The patented dryer design with built-in filter, (Figure 23), uses proven spray drying systems such as:

Feeding system with heating, filtration and concentrate homogenization, equipped with high-pressure pumps. The equipment is the same as in traditional spray dryers.
Spraying is done either by jet nozzles or by an atomizer. Jet nozzles are used mainly for fatty or high protein products, while rotary atomizers are used for any product, especially those containing crystals.
The drying air is filtered, heated and distributed by a device that creates a rotating or vertical flow.
The drying chamber is designed to ensure maximum hygiene and minimize heat loss, for example through the use of removable
hollow panels.
The integrated fluidized bed is a combination of a back-mix bed for drying and a piston-type bed for cooling. The fluidized bed apparatus is completely welded and has no cavities. There is an air gap between the backmix layer and the surrounding piston-type layer to prevent heat transfer. It uses the new patented Niro BUBBLE PLATE.

The air removal system, while revolutionary, is based on the same principles as the Niro SANICIP bag filter. The fines are collected on filters built into the drying chamber. The filter bags are supported by stainless steel mesh, attached to the ceiling around the circumference of the drying chamber. These filter elements are backflushed clean, just like the SANICIP™ filter.

The hoses are blown out one or four at a time with a stream of compressed air, which is fed into the hose through a nozzle. This ensures regular and frequent removal of the powder that falls into the fluidized bed.

It uses the same filter material as the SANICIP™ bag filter and provides the same air flow per unit area of material.

The backflush nozzles serve two functions. During operation, the nozzle serves for purging, and during CIP, liquid is supplied through it, washing the hoses from the inside out to the dirty surface. Clean water is injected through the backflow nozzle, sprayed with compressed air on the inner surface of the hose and squeezed out. This patented design is very important because it is very difficult or impossible to clean the filter media by external washing.

To clean the underside of the chamber ceiling around the sleeves, specially designed nozzles are used, which also play a dual role. During drying, air is supplied through the nozzle, which prevents powder deposits on the ceiling, and when washing, it is used like a regular CIP nozzle. The clean air chamber is cleaned using a standard CIP nozzle.

Benefits of installing IFD™

Product

Higher yield of premium powder. In traditional dryers with cyclones and bag filters, the second grade product is collected from the filters, the share of which is approximately 1%.
The product is not subjected to mechanical stress in channels, cyclones and bag filters, eliminating the need to return fines from external separators, since the distribution of flows within the dryer ensures optimal primary and secondary agglomeration.
Product quality is improved because the IFD™ can operate at a lower exit air temperature than a traditional spray dryer. This means that higher drying performance per kg of air can be achieved.

Safety

The protection system is simpler, since the entire drying process takes place in one apparatus.
Fewer components require protection.
Lower maintenance costs

Design

Easier installation
Smaller building sizes
Simpler support structure

Environment protection

Less possibility of powder leakage into the working area
Easier cleaning as the contact area between the equipment and the product is reduced.
Less waste volume with CIP
Less powder emission, up to 10-20 mg/nm3.
Energy savings up to 15%
Lower noise level due to lower pressure drop in the exhaust system

Characteristics of raw materials and semi-finished products. Powdered milk products are a type of canned milk. The latter can be divided into three groups: condensed with sugar, sterilized and dry. Dry milk products are a powder made from agglomerated milk particles of different shapes and sizes, depending on the type of product and the drying method.

Dry dairy products have high nutritional and energy value. Whole milk powder contains 25.6% protein, 25% fat, 39.4% lactose, and skim milk powder contains 37.9% protein and 50.3% lactose. These foods are also high in vitamins and minerals. The energy value of 100 g of dry dairy products is 1500...2500 kcal. The moisture content of dry dairy products does not exceed 4%, which ensures a significant shelf life in sealed packaging. One of the main physicochemical indicators of dry canned food is solubility, the value of which can range from 80 to 99.5% depending on the drying method.

The range of dry dairy products is very diverse. The main type of dry milk products produced by the domestic dairy industry is powdered cow's milk with a mass fraction of fat of 15, 20, 25% and skim milk, dry cream, as well as dry fermented milk products and buttermilk.

The raw materials for the production of dry dairy products are milk of at least 2nd grade and an acidity of no more than 20 °T, cream with a mass fraction of fat of no more than 40% and an acidity of no more than 26 °T, skim milk and buttermilk with an acidity of no more than 20 °T.

Features of production and consumption of finished products. The volume of production of natural milk and other dairy products is uneven throughout the year, especially in the autumn-winter period, when the supply of fresh milk is reduced. One of the ways to ensure rhythmic dairy production is to use milk powder produced in special dairy production facilities. In addition, milk powder makes it possible to economically store and transport very large quantities of dry matter to remote regions and for export.

Features of the production of dry milk products in comparison with the production of drinking milk involve the implementation of additional operations of heat treatment of milk: evaporation and drying.

Evaporation designed to remove water and increase the concentration of non-volatile solids (up to 50%), resulting in the formation of condensed milk.

Such milk or milk mixture is a colloidal system. Salts and carbohydrates are contained in condensed milk in the state of a molecular solution, proteins in a colloidal solution, and fat in the form of an emulsion.

Milk is usually evaporated under vacuum when the boiling point of the product is lowered. This method allows you to improve the technological performance of equipment and reduce the negative impact of high temperature on the quality of milk powder. Depending on the number of evaporation stages, the boiling temperature is maintained from 70...80 °C to 43...48 °C.

The ratio of the final concentration of any milk component to its initial concentration is usually called the degree of thickening. The value of the latter depends on the design of the evaporation equipment. The degree of milk condensation in a circulation vacuum evaporator is 43...48%, and in a film evaporator - 52...54%, with a condensation duration of 50 and 3...4 minutes, respectively.

Drying designed to produce a dairy product with a solids concentration of at least 96%. Milk is usually dried in contact or spray dryers. In contact dryers, milk dries by direct contact with the hot surface of drums (rollers). Depending on the design of these dryers, milk can be dried at atmospheric pressure at a temperature of 110...130 °C and in vacuum at a temperature of 60...70 °C. Water vapor is used as a drying agent, supplied to the inside of the drums and heating their working surfaces.

In spray dryers, milk is dispersed into fine droplets using rotating discs or nozzles. Increasing the specific surface area of the product during drying makes it possible to intensify the release of moisture. Due to the small size of milk droplets (40...50 microns), the moisture exchange surface reaches 150...250 m 2 per cubic meter of the drying chamber. Therefore, the drying duration does not exceed 4...6 s.

The shelf life of whole milk powder in sealed packaging at a temperature of 1...10 °C is no more than 10 months.

Stages of the technological process. The production of milk powder consists of the following stages and main operations:

– receiving milk, sorting by quality and measuring the amount of milk received;

– cleaning from mechanical impurities and cooling of raw milk;

– heating and separation of milk;

– formation of a normalized milk mixture: normalization, purification and pasteurization;

– condensation of normalized milk;

– homogenization of condensed milk;

– drying condensed milk;

– cooling of powdered milk;

– packaging of the finished product in consumer and transport containers.

Characteristics of equipment complexes. The milk powder production line begins with a set of equipment for preparing raw milk for processing, including self-priming pumps, flow meters, filters, cooling units and milk storage tanks.

Next in the line is a set of equipment for the formation of normalized milk formula, containing pumps, heat exchange units, separators, component dispensers, tanks and filters for normalized milk formula.

Next, the line contains a set of equipment for condensing milk, which has multi-body vacuum devices or circulating vacuum evaporators, homogenizers, filters and tanks for cooling condensed milk.

The leading one is a set of equipment for drying milk, including dryers, vibrating screens and devices for cooling milk powder.

The line ends with a set of equipment for packaging milk powder into consumer and transport containers.

The machine and hardware diagram of the milk powder production line is shown in Figure 2.19.

Design and operating principle of the line. After quality control, accounting, cleaning and cooling, raw milk is loaded into receiving tanks 1 . Raw milk is pumped for processing using a centrifugal pump. 2 via plate heater 3 , milk separators 4 into the separator-normalizer 5 .

Milk is normalized by adding cream, skim milk or buttermilk. In a normalized milk mixture, the ratio of fat to nonfat milk solids should be the same as in the finished product. Normalized tank milk 6 pumped into a pasteurization-cooling unit 7 . Milk is pasteurized at a temperature of 95 °C without holding, filtered and loaded into supply tanks 8 .

Rice. 2.19. Machine and hardware diagram of the milk powder production line

The milk is condensed in a film-type vacuum evaporation unit. The installation includes three heating chambers 10 with steam separators 11 , tubular heaters 13 And 14 , product pipeline with pumps 12 , heating steam supply system 9 , capacitor 17 with steam jet pumps 18 and pumps for pumping condensed milk 15 and condensate 16 .

For evaporation, milk is pumped from above into the pipes of the heating chamber 10 and flows down, forming a thin film on the inner surface of the tubes. Heating steam enters the annulus and heats the product to boiling point. The vapor-liquid mixture of the product from the lower section of the heating chamber enters the steam separator 11 . In it, the flow is divided into secondary steam, which is supplied to heat the next chamber, and the evaporated product, which is pumped into the pipes of the next chamber. From the last (third) chamber, condensed milk is pumped 15 to the intermediate tank 19 , and the secondary steam enters the condenser 17 , turns into liquid and is pumped 16 into the condensate collection system.

In order to prevent fat sedimentation, condensed milk is homogenized. This operation is carried out in a two-stage homogenizer 20 valve type. The product is heated to 55...60 °C and homogenized at a working pressure of 11.5...12.5 MPa at the first stage and 2.5...3.0 MPa at the second stage. Homogenized condensed milk is filtered and accumulated in a stirrer bath 21 .

Condensed milk is supplied for drying using a gear pump 22 passing through a spray disc 24 for dispersion. Sprayed product in the working volume of the drying tower 25 dried in an atmosphere of hot air forced through a heater 23 . The temperature of the air entering the drying tower is 165...180 °C, and the temperature of the exhaust air is 65...85 °C.

Powdered milk is unloaded from tower 25 using cyclones 26 And 27 , sifted on a sieve with a mesh size of 22 mm and cooled to 15...20 °C in a pneumatic transport system 28 . Chilled milk powder is packed into consumer containers using a machine 29 . Packages of milk are placed in boxes.

For many centuries, people have consumed fresh milk, The dairy industry was actively developing, and the volume of milk produced increased. There was a need to stock milk for a long time and to be able to transport it over long distances.

Powdered milk was first mentioned by Ivan Erich in the “Proceedings of the Free Economic Society,” dated 1792. He wrote that residents of the eastern regions, by freezing milk, received “supplies of milky lumps.”

In 1802, the headquarters physician Osip Krichevsky was the first to obtain a product that is currently known as powdered milk. Commercial production of milk powder first took place in 1832, launched by the Russian chemist M. Dirchov. And in 1885, Grimwade T.S. was issued a patent for the production of this product.

Canning by drying is widely used in the dairy industry:

dry whole and skim milk;
buttermilk;
whey;
mixtures of whole milk with skim milk, buttermilk or cream, with or without additives.

The range of dry dairy products is quite extensive:

whole milk powder 20% and 25% fat content;
dry cream;
dry skimmed milk;
dry whey;
dry milk products of increased solubility;
dry multicomponent mixtures (dry mixes for ice cream, pudding).

These products are produced by spray drying.

Powdered milk is used:

in the confectionery industry;
at bakery enterprises;
in dairies for the production of condensed milk, processed cheese, yogurt, cottage cheese;
for the production of spreads;
in the meat industry;
in the production of alcohol;
in the production of semi-finished products;
in the production of animal feed.

Powdered milk divided into two types:

whole milk powder with m.d.z. not less than 20%-Whole milk is used as raw material;
dry low fat milk (COM) with m.d.j. no more than 1.5% - skimmed milk (skimmed milk) is used for its production.

The flowability of dry dairy products depends on the force of friction and adhesion of the particles to each other. The high mass fraction of dry substances ensures high transportability and storage of dry dairy products. The mass fraction of moisture in milk powder depends on the type of product and ranges from 1.5 to 7%. The shape of the particles and, as a consequence, their solubility depends on the drying method and technology.

Single particles have a cavity and are penetrated by a network of cracks and capillaries, some of which communicate with internal cavities. It is assumed that due to the high mass fraction of milk protein in milk powder, its micelles in the particle are in contact with each other and also form a spatial framework.

Lactose in the particle may be in a crystalline state. In this case, lactose crystals can be located both on the surface and inside the particles. Crystallized lactose has a direct effect on particle porosity.

Milk fat, which has a shape close to spherical, is generally evenly distributed in particles, located both on the surface and inside, including on the surface of cavities and capillary walls. Conventionally, fat is divided into three main groups: superficially free fat, fat contained in the internal areas of the cavities and protected fat, which is not extracted by a fat solvent in the absence of mechanical action on the milk powder particles. The mass fraction of free surface fat ranges from 0.5 to 20.0%.

Theoretical basis of drying

Drying is the process of removing moisture. In the production of all types of dry dairy products, the process of removing free moisture is carried out in two stages - condensation and drying of the condensed product. Thickening by evaporation is carried out to such a value of the total mass fraction of dry substances at which the mass fraction of CCFC in water does not exceed 18-20% and the product does not lose fluidity.

The condensed mixtures are dried to the final moisture content, which is determined depending on the forms of communication of water with the components of the dry matter of the dry matter. The final moisture content of a dry milk product, which is bound water, is no more than 15% of the mass fraction of protein in it. This is the basis for the standardization of the mass fraction of moisture in dry dairy products, upon reaching which the drying process ends.

Whole milk contains bound moisture along with free moisture. Bound water is inaccessible to microorganisms, is not a solvent, does not participate in microbiological and biochemical processes, and does not freeze at 0°C. It is firmly connected with the components of milk. Its removal is accompanied by irreversible changes in the dry matter of the processed raw milk. Based on the above, bound water should be left in the milk powder.

When drying in a stream of hot air or by contact, do not allow the dry powder to overheat, dry out or burn.

Whole milk powder

All technological operations for producing milk powder can be divided into two groups:

processing of raw materials before drying;
drying and all subsequent operations.

Technological operations of the first group are common for the production of canned milk:

acceptance, quality assessment, sorting, cleaning, cooling and reserve;
normalization of milk composition, heat treatment, thickening;
homogenization of condensed milk.

The second group of operations is:

drying, cooling of dry product;
packaging, packing, storage.

When producing milk powder, milk normalized for fat and dry matter is pasteurized at a temperature of at least 90°C. To thicken normalized milk, multi-effect vacuum evaporation units operating on the falling film principle or circulation units are used. The technical parameters of thickening are maintained within the limits specified in the operating instructions for the vacuum evaporation units used.

The need to homogenize condensed milk is due to the fact that during mechanical, heat treatment and thickening, the fat fraction of milk is destabilized (release of free fat), which contributes to fat oxidation and spoilage of the product during storage. Therefore, to increase stability and reduce free fat content, milk is homogenized. Homogenization is carried out at a temperature of 50–60°C and a pressure of 10–15 MPa for a one-stage homogenizer; for a two-stage homogenizer at a pressure of 11.5–12.5 MPa at the first stage and 2.5–3.0 MPa at the second stage. After homogenization, the condensed milk enters an intermediate container and then is dried.

In whole milk powder, the mass fraction of fat is 20–25% and moisture no more than 4–7%. Based on the composition of powdered milk, we can conclude that it is not absolutely dry, it contains so-called irremovable moisture. As the product dries, the moisture remaining in the product is retained more and more firmly in it due to increased adhesive forces and increased resistance to water movement. Therefore, the product can only be dried to an equilibrium moisture content corresponding to the relative humidity and temperature of the drying agent.

Depending on the method of moisture removal, different drying methods are used: film (contact), spray (air) And sublimation.

Drying units are prepared before feeding the condensed product. To do this, the spray dryer chamber is heated for 15-20 minutes and hot water is sprayed for 5-7 minutes. Contact dryers are heated by passing hot water.

The drying mode is controlled by the main indicator - the temperature of the hot air entering the dryer and leaving it.

Film method

With the film method drying is carried out in roller dryers. Condensed milk is applied by spray or a thin layer onto rotating rollers, the surface of which is heated by steam to a temperature of 105–130°C. As a result of contact of the dried product with the hot surface of the rollers, the milk is dried in the form of a thin film. This film is removed with special knives and goes to the mill elevator for grinding. The drying process on roller dryers should not exceed 2s, since the high temperature of the heating surface causes significant changes in the dried milk. As a result of contact with a heated surface, a significant part of the fat is not protected by the shell. In this regard and due to the low solubility of the finished product, the film method is used in the production of skimmed milk powder and whey.

Freeze drying

By freeze drying moisture removal occurs from frozen products with a dry matter content of up to 40%. The freeze drying process is carried out at a frozen product temperature of 25°C and a residual pressure in the sublimator of 0.0133–0.133 kPa. Products obtained by freeze-drying are easily restored and retain their taste, chemical composition and structure. Dry fermented milk products, starter cultures, and ice cream mixtures are produced by freeze-drying.

Spray drying

With the spray method drying is carried out as a result of contact of the sprayed condensed product with hot air. Condensed milk is sprayed into the drying chamber using disc and nozzle sprayers. In disk sprayers, condensed milk is sprayed under the action of the centrifugal force of a rotating disk, from the nozzle of which the milk comes out at a speed of 150–160 m/s and is crushed into tiny droplets due to air resistance. Condensed milk is supplied to the nozzle sprayers under high pressure (up to 24.5 MPa).

When drying with spray dryers, condensed milk is sprayed into the top of the dryer, where hot air is supplied. Hot air, mixing with the smallest drops of milk, gives them part of the heat, under the influence of which the moisture evaporates and the milk particles quickly dry. The high rate of drying (evaporation) is due to the large contact surface of fine milk with hot air. With the rapid evaporation of moisture, the air is cooled to 75–95°C, so the thermal effect on the product is insignificant and its solubility is high. The dried milk in powder form settles to the bottom of the drying tower.

The most rational and progressive are high-performance direct-flow spray dryers, in which the degree of solubility of milk powder reaches 96–98%.

The prepared milk is purified using a centrifugal milk purifier, then normalized and pasteurized under the conditions described above. After pasteurization, the milk is supplied for condensation to a three-stage vacuum evaporation unit operating on the falling film principle. Milk condensed to a dry matter mass fraction of 43–52% is homogenized and sent to an intermediate container equipped with a stirrer and a heating jacket. From the intermediate container, condensed milk is pumped into the drying chamber. Moreover, it must have a temperature of at least 40°C.

In accordance with the technical characteristics of spray dryers, the following drying modes must be observed:

the temperature of the air entering the direct-flow type drying unit should be 165–180°C, and at the exit from the drying tower - 65–85°C;
for drying installations with mixed movement of air and product, the temperature of the air entering the drying tower should be 140–170°C, and at the exit from the tower - 65–80°C.

At the exit from the drying tower, whole milk powder is sifted on a shaking sieve and sent for cooling.

Instant milk

This is a dry powder consisting of agglomerated particles, with a taste and smell characteristic of pasteurized milk; with a mass fraction of fat - no less than 25 and 15%, moisture - no more than 4%, soybean-phosphatide additives - no more than 0.5%.

Features of the production of instant milk include two-stage drying, recycling of small particles involved in the formation of agglomerates, and the addition of soybean-phosphatide additives. When producing instant milk, the first drying stage produces regular milk powder, which is then moistened. When a dry product is moistened, milk particles enlarge, i.e., agglomerate, and lactose transitions from an amorphous to a crystalline state. At the second stage, the moistened product is dried to standard moisture. Due to agglomeration, milk particles dried at the second stage acquire a porous structure. When milk with a porous structure is dissolved, water penetrates into the particle and promotes its dissolution. Rapid penetration of water is also achieved by increasing wettability through the addition of soybean-phosphatide additives.

The technological line for the production of instant milk is similar to the production of powdered milk from receipt to drying, but includes the following additional stages: agglomeration of powdered milk particles, return of the cyclone fraction, drying, preparation of soybean-phosphatide additives and their addition to the powdered milk. Drying of condensed milk is carried out until the mass fraction of moisture in the milk powder at the exit from the tower is (3.75±2.25)%. The resulting milk powder is fed into the agglomeration chamber, where it is additionally moistened with buttermilk or skim milk to a moisture content of 7–9% and agglomerated in a fluidized bed. In this case, the cyclone fraction is returned to the sintering chamber for re-wetting and agglomeration. The wet powder from the sintering chamber is sent to the first section of the instantizer, where the product is dried in a fluidized bed to a mass fraction of moisture (4.25±0.25)% at an air temperature of (105±15)°C.

A mixture of soybean-phosphatide additives with ghee, prepared according to the recipe, is melted at a temperature of (65±5)°C and mixed. The mixture is then fed into the nozzles and sent to the milk powder. After adding the additives, the product is dried to standard moisture in the second section of the instantizer at an air temperature of (75±5)°C. Then the finished product is cooled to 25 °C in the third section of the instantizer.

Cooling of milk powder can be carried out either by air in a pneumatic transport system or in a fluidized state of the product. The cooled dry product is transported from the intermediate storage bin for packaging.

Dry milk products are packaged in sealed consumer and transport containers. Consumer packaging includes metal cans with a solid or removable lid and a net weight of 250, 500 and 1000 g; combined cans with a removable lid, having a net weight of 250, 400 and 500 g with an internal hermetically sealed bag made of aluminum foil, paper and other materials; glued packs with cellophane inserts with a net weight of 250 g. Instant milk powder is packaged under normal conditions or in a nitrogen environment with preliminary vacuuming. Unimpregnated four- and five-layer paper bags are used as transport containers; cardboard stuffing drums; plywood-stamped barrels with polyethylene liner bags with a net weight of 20–30 kg.

Powdered whole milk in consumer containers (except for glued packs with cellophane liners) and transport containers with polyethylene liners is stored at a temperature of 0 to 10 ° C and a relative air humidity of no more than 85% for no more than 8 months from the date of production. Powdered milk in glued packs with cellophane liners and stamped plywood barrels with cellophane and parchment liners is stored at a temperature of 0 to 20 ° C and a relative air humidity of no more than 75% for no more than 3 months from the date of production. Instant milk powder of 15 and 25% fat content is stored at a temperature of 1 to 10°C, relative humidity no more than 85% and no more than 6 months from the date of production.

To expand the range of dry dairy products, products with low and high fat content, dry fermented milk products and ice cream mixtures are produced.

Dry fermented milk products produced from normalized condensed milk, fermented with pure cultures of lactic acid bacteria, by drying in spray drying units. The production of dry fermented milk products is similar to the production of whole milk powder with the introduction of an additional operation - fermentation of condensed milk.

Dry mixes for ice cream is obtained by spray-drying pasteurized mixtures prepared from whole, skim milk, cream, sugar, stabilizer and fillers, or by mixing dry milk base with powdered sugar. Features of the production of dry ice cream mixtures include additional operations for preparing the components and composing the mixture.