Good afternoon dear friends! Coffee is one of the drinks that is consumed by quite a lot of people, regardless of their place of residence and nationality. Coffee contains a large number of organic and inorganic substances, which have a significant impact on the entire human body as a whole.

What do we know about coffee? Many of us can name only one single substance in coffee - caffeine, which affects us and gives us energy.

However, in fact, the chemical composition of this drink is very complex and is represented by many different substances, which many are not even aware of.

For example, roasted coffee contains over 1000 chemical compounds of various types. So, a small part of what is included in a coffee drink is represented by proteins, amino acids, alkaloids, minerals and many other substances.

Chemical composition of coffee

Many people are concerned and interested in the question: what is included in coffee? The chemical composition of coffee consists of chemical compounds that are found in the green beans and then added as they are roasted.

This suggests that roasted grains contain many more different substances than green ones. As mentioned above, there are more than 1000 such substances, where about 800 determine the taste of the drink.

A study of the chemical composition of coffee suggests that the main active ingredients in it are the following:

• Caffeine. It is he who helps us wake up in the morning and gives us energy for the whole day. Everyone who prefers it knows about the content of this substance in the drink. It is worth noting that caffeine was named after coffee, since it was first obtained from coffee beans. The substance helps improve performance and awaken mental abilities. To make a real coffee drink, it must contain caffeine in an amount of 0.7%. This figure will depend on the ripeness of the coffee beans and the degree of roasting. So, 1 tsp. Ready-made ground coffee contains about 0.1-0.2 g of caffeine. It is important to remember that it is recommended to drink a serving of coffee at a time not exceeding 0.3 g of pure caffeine. You will be able to enjoy your drink again no sooner than after 4 hours.
• Trigonelline. It has no taste or smell, but when heated it becomes a different substance and gives the drink its aroma.
• Vitamin B3. Stimulates the nervous system.
• Nicotinic acid, when combined with trigonelline during heating, ensures the content of Vitamin B3 in the required amount constantly.

The composition of the coffee bean is completely determined by the degree of roasting, as well as the plantation on which it was grown. After processing, the composition of coffee beans is represented by various types of vitamins. Here are the following vitamins:

• vitamin A, which helps the body develop and grow;
• vitamin D, which ensures the absorption of phosphorus and calcium;
• Vitamin E – stimulates the immune system.

In addition, black coffee contains amino acids and proteins. They give the body energy and nourish it. Amino acids in coffee beans of plant origin. They help the body recover and support immunity.

Coffee contains a large number of organic and inorganic substances, which have a significant effect on the entire human body as a whole.

Green coffee beans contain up to 50% carbohydrates. It contains sugars, polysaccharides and some other substances that help form the basis for nourishing the brain and nerve cells.

The minerals that make up ground coffee, as well as beans, are calcium, potassium and magnesium. They ensure strong bones, are also responsible for muscle function, and stimulate the functioning of the brain and heart.

However, it is worth remembering that excessive consumption of this drink does not lead to anything good, since an excess of caffeine causes the pulse to increase and the heart to beat at an accelerated pace.

Due to the high content of essential compounds in coffee beans, the drink is rightfully considered the most aromatic. Thus, green grains contain about 800 of these compounds, and fried grains - 350.

Composition of instant coffee

The chemical composition of instant coffee is far from the same as that of grain coffee. It is worth noting that this is because many instant drink manufacturers add various chemicals for flavor and color that are not found in natural coffee.

It should also be said that some manufacturers do not include any additional additives in the drink and retain the properties of natural coffee. Thus, instant coffee without additives includes the same elements as grain or ground coffee.

Some people prefer to drink without caffeine, due to the fact that not everyone can drink it due to insomnia, nervous breakdowns and other diseases. Here, caffeine is replaced by a substance such as carbonic acid.

Most instant coffee contains no more than 20% of the natural elements that should be in it and about 80% - flavors, dyes and other additives.

Based on this, it becomes clear that a grain or ground drink can never be replaced with a soluble one due to the naturalness of the former. If you can’t devote enough time to preparing the delicacy, then you should find instant coffee that does not contain additional substances. As a rule, such a drink is called organic, which means natural.

Nutritional value of coffee

Coffee is varied in its composition, but any type is low in calories, which allows the drink to be consumed even by those who are on a diet. It's a different matter when it comes to coffee with milk or cream and sugar. Here the caloric content is significantly increased due to additives.

Thus, pure coffee can be drunk often, if we consider this issue from the calorie side. However, it is important to remember to use the product in moderation.

Coffee, as mentioned above, can have different composition depending on the variety.

However, the chemical composition of coffee in the table in various sources suggests that the content of substances in different types of coffee is approximately the same. So, per 100 g of dry product there are:

• fats – 0.6 g;
• proteins – 0.2 g;
• carbohydrates – 0.1 g;
• calcium – about 5 mg;
• vitamin B3 – 0.6 mg;
• potassium – 9 mg;
• iron – 2 mg;
• phosphorus – 7 mg.

The chemical composition of coffee beans is quite rich, which allows it to act on the human body both positively and negatively. Only he himself can know how a treat will affect a particular person, since there are contraindications to consuming the treat for some people.

This is often due to the caffeine content. For example, the drink is not recommended for people with high blood pressure.

Instant coffee without additives includes the same elements as grain or ground coffee.

It is worth considering in more detail the effect of delicacy on the human body:

• Excessive consumption of the drink is equivalent to addiction. This is due to excessive intake of caffeine, which is contained in this drink. This addiction can be equated to alcohol or any other;
• The treat has a diuretic property, so if you are dehydrated, it is not recommended to drink it in any form. It is best in this case to replace the drink with water;
• people who do not have heart problems or blood pressure may experience a slight increase in blood pressure after drinking the drink. If the drink is consumed by a hypertensive person, the blood pressure may rise much higher than in healthy people. In this regard, the use of the drink should be postponed or replaced with others. Thus, it is recommended to drink coffee with a reduced caffeine content or without it at all. Fortunately, now you can find it without problems in any store;
• The drink has no effect on the heart. The misconception is that, on the contrary, it worsens the functioning of the heart and is confused with an increase in blood pressure or nervous excitability;
• unfiltered delicacies often increase cholesterol, which complicates the functioning of blood vessels and leads to increased blood pressure;
• The increase in productivity, performance and mental focus only occurs for a while. So, the duration of the drink in this case can be from 30 minutes to 2 hours. You won’t be able to use this effect all day;
• oddly enough, coffee can enhance the effect of some medications, such as aspirin, analgin and some antispasmodics;
• the drink reduces the likelihood of certain diseases, such as Alzheimer's disease. This effect can be explained by the fact that the brain is trained due to the vasoconstrictor effect;
• the treat prevents constipation, breast cancer and even cirrhosis of the liver;
• The older generation should limit their consumption of the drink due to the fact that the drink reduces bone density. Often this leads to cracks and fractures appearing almost out of nowhere;
• those who drink more than 2 cups of drink per day risk increasing the likelihood of developing kidney stones;
• coffee increases the likelihood of developing pathologies in the fetus if a pregnant woman drinks more than 1 serving per day. Some women generally prefer to give up drinking during pregnancy in order not to harm their baby.

After analyzing this list, we can say that coffee can affect a person’s condition and his body, both positively and negatively.

Coffee is one of the few drinks of natural origin, the biochemical composition of which includes a huge number of organic and inorganic elements that have a significant impact on the condition and functioning of all systems and tissue structures of the human body. Despite all their efforts, scientists have not yet been able to create an artificial coffee substitute that can accurately convey its unique aroma and taste. A situation exactly reminiscent of futile attempts to create an analogue of breast milk. Obviously, nature is reluctant to reveal its treasured secrets to man.

About the chemical composition of coffee

The biochemical composition of coffee is extremely complex: it contains about two thousand chemical components, the combination of which gives its characteristic taste and aroma. Only half of these substances have been studied. Thanks to modern methods of chemical analysis, it has been established that natural coffee contains several hundred organic substances that determine the taste and aromatic properties of our favorite drink, and each variety has its own unique set of these components.

The richness of the chemical composition and the percentage of substances in coffee beans are determined by climatic conditions and soil characteristics, and the characteristics of their taste and aroma are determined by the roasting technology and method of preparation, during which natural substances undergo a number of complex chemical metamorphoses. Thus, each stage of processing coffee beans (including the preparation of the drink) consistently ends with a modification of their chemical composition. The essence of the processes occurring in this case is the subject of study by many world research centers.

Composition of green coffee beans

A quarter of the mass of raw coffee beans comes from caffeine, chlorogenic acid, trigonelline, mineral salts and vegetable proteins. The remaining three-quarters of the weight is made up of plant fiber, coffee oil and water. Coffee fruits are champions in the content of chlorogenic acid, which gives them a tart, slightly acidic taste: no other product contains it in such quantities.

Arabica beans have a low caffeine content, while low-grade African Robusta fruits have the highest amount of caffeine (over 3%). The process of storing coffee does not affect the caffeine content in any way, but roasting leads to an increase in its mass fraction. The content of coffee oil in different types of coffee varies significantly. Indian varieties have the least amount of fat. The highest protein content is in African robusta.

About the composition of roasted coffee beans

The composition of roasted coffee beans is determined not only by the growing conditions, but also by the duration of roasting. During this process, the grains, losing a significant part of the liquid and from 14 to 23% of the weight, at the same time (due to gas formation) acquire additional volume. Raw coffee fruits contain many alkaloids, phenols, proteins, amino acids, disaccharides, lipids, mineral salts, natural acids and a number of components present in trace amounts.

During roasting, new chemical compounds are formed in them, enriching the already diverse chemical composition, numbering more than a thousand components, eight hundred of which determine the taste of the finished drink. In addition to the delicious aroma, roasting gives the beans the well-known dark color. Roasting rids the grains of their moisture content; When sugar is caramelized, caramel is formed (which colors the beans brown) and caffeol, a multicomponent compound that is the source of the characteristic coffee aroma. In the process of decomposition of chlorogenic acid, which is contained in significant quantities in the fruit, coffee acquires its astringent tart taste.

Roasting is equally destructive to tannins - natural substances that give the drink a bitter taste. With this in mind, beans should be roasted carefully. Another source of unique aroma is the alkaloid trigonelline, the destruction of which during roasting produces nicotinic acid. The famous alkaloid caffeine tolerates this process completely differently. After frying the fruits, which lose most of their moisture, its amount (as a percentage of the mass of raw materials) even increases.

The invigorating effect of coffee is provided by the presence of caffeine. Researchers have always been interested in the question, thanks to which component contained in coffee fruits, the drink prepared from them has the ability to drive away sleep and give vigor.

This crystalline, colorless substance was isolated by the German researcher Runge in 1819 and was named caffeine. Upon further research, caffeine was found in tea leaves, mate, cola, guarana, and cocoa. It has been found that plants synthesize it to protect themselves from insect pests and to attract pollinators. Caffeine increases motor activity, speeds up reactions, improves brain activity and nervous system function. The caffeine content is determined by the type of coffee. In the best Arabica varieties, characterized by a mild taste and pleasant aroma, the beans contain from 0.5 to 1.5% caffeine, and in Robusta fruits it can be from 1.5 to 4.5%.

Caffeine is an alkaloid; after roasting, it does not disintegrate and its amount does not decrease when compared with green caffeine. More precisely, the amount of caffeine in the roasted bean increases, but only in proportion to the decrease in the weight of the bean, which loses liquid during roasting.

The chemical composition of coffee depends on its variety, as well as on the method and level of roasting. 100 ml of a drink made from fried fruits contains (on average): proteins (0.2 g), fats (0.5 g), carbohydrates (0.2 g). Convinced fans of strong black coffee become almost as dependent on it as smokers are on tobacco. Despite the harm caused to the body by countless cups of coffee, lovers of this drink cannot deny themselves the pleasure of drinking another cup. Meanwhile, drinking natural coffee is contraindicated for patients with gastric and duodenal ulcers, diseases of the cardiovascular system, chronic colitis and enterocolitis. It is not advisable to drink it if you are prone to neuroses, insomnia and thyrotoxicosis.

What should people do who are contraindicated from drinking coffee? Do they really need to forget the taste of this wonderful drink forever? Of course this is not true. In modern supermarkets you can find many coffee drinks, the composition of which either does not contain natural coffee, or its amount does not exceed 35%. When preparing coffee drinks, plant raw materials are used, during the brewing process they produce a drink whose taste and aroma resembles natural coffee, and the absence of caffeine and caffeine makes it safe for the health of people suffering from the above ailments. In addition, some countries have learned to make decaffeinated coffee, the caffeine content of which is almost zero.

Most often, we don’t even think about what we eat and drink - I mean, of course, the chemical composition of foods and drinks, and not their consumer properties. But sometimes you still want to know what your favorite food or drink is made of. For example, coffee, the composition of which cannot be described in a few words. That is why we will devote an entire article to it, in which we will talk in detail about the substances that make up coffee and even the chemical elements. Although, in fairness, I note that for a detailed description of all the compounds included in coffee, and even more so, their interactions, a whole book would be needed.

Chemical composition of coffee

It's quite complicated. Coffee contains a huge number of different chemical compounds, and new ones are also added during the process of roasting coffee beans. The total number of different substances contained in coffee reaches several hundred. Roasted coffee contains about a thousand chemical compounds, of which eight hundred are responsible for its taste and smell. Of the extractive (excreted) substances that make up almost any type of coffee, we can note such groups as proteins, alkaloids, mono- and disucrose, phenolic compounds, lipids, amino acids, organic acids, mineral elements and some other chemical compounds that are contained in coffee in extremely small quantities.

Chemical composition of coffee - proteins and carbohydrates

As for proteins, there are not so many of them in coffee - a maximum of 9-10%, most of which is the so-called amine nitrogen (about 1.5%), that is, nitrogen that is part of the amino acids contained in coffee. There are much more carbohydrates in coffee: up to 50 and sometimes even up to 60% in raw coffee beans. Of the carbohydrates contained in coffee, the most are sucrose and cellulose - on average 8 and 8.5%, respectively. Also, lignin and fiber (so-called high molecular weight polysaccharides) and pectin carbohydrates are present in coffee in slightly smaller quantities. Of the high molecular weight polysaccharides, some have a high degree of solubility in water, and most notably arabinogalactan, a substance that is found in large quantities in various deciduous tree species. Arabinogalactan, by the way, has a beneficial effect on the intestinal microflora and helps protect the body's immune system. Also, substances such as mannose, galactose, arabinnose and glucogalactomannan are released from coffee beans during interaction with water. Fructose and glucose are also found in coffee in small quantities, although until recently it was believed that they were not there. Reducing saccharides - a group that includes fructose and glucose, depending on the type of coffee, are contained in quantities from 0.5 to 1%. Now let's talk about some of the most important substances in coffee, the composition of which, as you have already noticed, is incredibly complex.

Chemical composition of coffee - tannin

Tannin, or, as it is often called, tannin, is a substance whose main function is to bind other substances - in particular, proteins and polysaccharides. That is why it is so important to preserve tannin in those drinks and foods that contain it, because its destruction can lead to the breakdown of many other valuable compounds. Interestingly, the chemical composition of tannin (in terms of its constituent elements) is the same as that of water - it consists of oxygen and hydrogen, but the structure of the molecule and the quantitative content of these elements are, of course, completely different. In raw grains, tannin can make up a fairly large percentage - up to 7.7%. However, during roasting, a large amount of this valuable substance disintegrates or oxidizes, and in ready-made coffee the tannin content is no more than 1%. However, it is thanks to the decomposition of tannin that coffee acquires that unforgettable aroma and taste for which its true fans value it so much. Therefore, from the point of view of acquiring the desired taste, the breakdown of tannin is simply a necessary process.

Chemical composition of coffee - caffeine

Almost everyone knows about the presence of this component in coffee. By the way, it got its name thanks to this drink. The chemical formula of caffeine is: C 8 H 10 N 4 O 2, that is, it consists, like many other organic substances, of carbon, hydrogen, nitrogen and oxygen atoms. The molecular structure of caffeine is as follows: in the center there are carbon and nitrogen atoms, three hydrogen atoms are attached to the outer three carbon atoms, and one more is attached to the carbon atom bonded to two nitrogen atoms. The oxygen atoms are connected to two other bonded carbon atoms and, like hydrogen, are located at the ends of the structure. Caffeine has other names: guaranine, mateine, theine, as well as 1-3-7-trimethylxanthine and 2-6-dioxy-1-3-7-trimethylpurine. We won’t delve further into the chemical topic, but let’s talk about the properties of caffeine and the peculiarities of its content in coffee.

Caffeine is odorless and colorless, and when dissolved in water it gives the drink a bitter taste. It is bitterness that can explain the taste of brewed coffee. Caffeine melts at a temperature of 236 degrees Celsius, and if it is subjected to gradual heating, it can even sublimate, that is, pass from a solid to a gaseous substance immediately, without turning into a liquid. In different types of coffee, caffeine can have varying degrees of content - from 0.6 to 3%. In addition to coffee beans, caffeine is found in large quantities in tea and coca leaves, as well as in mate and guarana. As for the medicinal properties of caffeine, it is known that it stimulates brain receptors, increasing motor activity and improving reactions. This is why many cyclists (and caffeine has recently been re-allowed in cycling) consume caffeine bars, which significantly improve their performance, during the race.

Chemical composition of instant coffee

Here it must be said that instant coffee, in its chemical composition, is, of course, very different from natural coffee. The fact is that to improve the taste, as well as the color and smell of instant coffee, almost all manufacturers use various chemical additives. However, there is also high-quality instant coffee, which does not contain any additives. The process of its production is as follows: the coffee extract in this case is simply dried and then packaged. This instant coffee is called organic because its composition is no different from natural coffee (except for adjustments for the effects of water and heat).

There is also instant coffee with zero caffeine content, but in this case, instead of caffeine, it contains carbonic acid. As for the vast majority of instant coffee varieties, the natural substances initially present in coffee make up no more than 20% of these drinks. And the remaining 80% consists of all kinds of additives: flavors, stabilizers, coloring agents and preservatives. That is why natural coffee - beans or ground - has always been and remains better than any instant coffee. If you choose instant coffee, then at least organic coffee, which contains a minimum amount of any such substances that do not have a very beneficial effect on our body.

Raw coffee beans primarily contain caffeine, trigonelline, chlorogenic acid, protein and mineral salts. This set of substances makes up a quarter of the mass of raw grain. The rest comes from fiber, coffee oil and water.

Caffeine is a member of the group of alkaloids. Coffee owes its invigorating effect to caffeine. Caffeine was isolated in its pure form from coffee beans in the 20s of the last century. Caffeine appears as colorless crystals with a bitter taste.

Trigonelline is also an alkaloid found in coffee beans. Unlike caffeine, it does not have a stimulating effect on the human body, but the taste and smell of roasted coffee beans depends on it.

Chlorogenic acid is one of the most valuable components of coffee beans.

Natural, unroasted grain is the only natural product with a high content of chlorogenic acid. By stimulating the functioning of the human digestive system, chlorogenic acid, which is part of green coffee beans, helps the body break down fats, which is why nutritionists around the world recommend green coffee beans for weight loss. When coffee beans are roasted, the content of chlorogenic acid decreases by 2-3 times, and the coffee acquires a characteristic, slightly astringent taste.

It should be added that coffee beans contain more than 30 different organic acids (including malic, citric, acetic and caffeic). In addition, coffee beans contain healthy fatty acids:

• linoleic - 52.2-54.3%;
• palmitic - 26.6-27.8%;
• oleic - 6.7-8.2%;
• stearic - 5.6-6.3%;
• arachidonic acid - 2.6-2.8%;
• linolenic - 2.2-2.6%;
• behenicum - 0.5-0.6%.

Despite such an abundance of useful substances, natural bean coffee is not a high-calorie product, although it contains proteins - 0.2 g, fats - 0.6 g and carbohydrates - 0.1 g. from natural grains no more than 1 -2 Kcal. Nicotinic acid and vitamin PP contained in coffee beans are active biological components. That is why coffee is considered low-calorie and not capable of harming a person’s figure.

However, do not forget that the daily portion of coffee from natural beans should not exceed 0.3 g of caffeine, which corresponds to two teaspoons of ground coffee beans per glass of water, and taking 4 cups of coffee beans per day is 1 g of caffeine, a person develops a constant need in coffee, comparable to alcohol addiction.

Raw coffee beans, calculated on a dry matter basis, contain 32-36% extractives, which are stable for seven years or more under normal storage conditions. The composition of the dry matter of raw coffee includes the following main components, in%: caffeine - 0.7-2.5; protein substances - 9-19.2; fat - 9.4-18; sucrose - 4.2-11.8; monosaccharides - 0.17-0.65; fiber - 32.5-33.5; pentosans - 5-7; tannins - 8.7-11.9; minerals - 3.7-4.5; organic acids: chlorogenic - 4-10.9, citric - 0.3, tartaric - 0.4, malic - 0.3, oxalic - 0.05, caffeic - 0.2. The humidity of raw coffee is 9-12%.

Of the listed substances, the alkaloid has the greatest effect on the human body when drinking coffee. caffeine(C 8 H 10 N 4 O 2), or 1,3,7-trimethylxanthine, which is a derivative of purine bases. Coffee has a beneficial physiological effect on the body due to its caffeine content, which is expressed in regulating blood glucose levels and increasing the overall tone and performance of a person. In coffee, caffeine is found both in a free state and in combination with potassium and chlorogenic acid in the form of caffeine-chlorogenic acid potassium; in this case, the bound form predominates. Higher grades of coffee have lower caffeine content, while low-grade African coffee robusta can accumulate up to 3.2% caffeine. During storage of coffee, the caffeine content in the beans practically does not change, but during roasting it increases, which is confirmed by the data in Table. 8.

Along with caffeine, the alkaloids in raw coffee beans also contain trigonelline (C 7 H 7 N0 2 - methyl betaine nicotinic acid), which does not have physiological activity, in an amount of 0.24-1.2%. It breaks down during roasting of beans into a number of compounds, including pyridine, which is involved in the formation of the taste properties of the finished coffee. In addition, theobromine (1.85 mg%) and theophylline (0.62 mg%) were found in coffee beans.

Contents specific to individual botanical species and coffee varieties protein substances. Arabian coffee contains approximately 3% less protein than coffee robusta, At the same time, intra-varietal fluctuations do not exceed 2%. A positive correlation has been established between the amount of caffeine and nitrogenous substances. During storage, their total content does not change, but an increase in the fraction of water-soluble proteins with a high degree of electrical conductivity is observed.

Also found in the nitrogenous substances of coffee are 20 free amino acids, the amount of which practically does not change during storage. At the same time, premium coffee has a higher content of free amino acids (up to 923 mg%) compared to coffee of the 1st and 2nd grades (up to 480 mg%).

Contents in coffee beans fat(coffee oil) is subject to significant interspecific and intraspecific fluctuations. Indian coffee varieties have the lowest fat content. A distinctive feature of coffee oil is its high content of diterpene esters. The share of unsaturated fatty acids in coffee oil accounts for more than half - 51.9-57.3%, including linoleic acid (37.2-45.6%).

In coffee oil made from different types and varieties of coffee beans, the qualitative composition of fatty acids is almost identical. When storing raw coffee, the acid and peroxide numbers of fat increase slightly, which indicates a slower progression of intracellular hydrolytic and oxidative processes.

Carbohydrates have a significant impact on the taste properties of coffee and, in particular, sugars, which are the precursors of many flavoring and aromatic substances of roasted coffee. Carbohydrates in coffee are represented by sugars, heteropolysaccharides and fiber.

Sahara coffee contains glucose, fructose, galactose and sucrose, which account for approximately 28% of water-soluble substances. Raw coffee of Arabian varieties contains 8.2-8.3% monosaccharides, while robusta contains 3.3-4.1%. During storage of raw coffee, the sugar content decreases slightly.

Heteropolysaccharides coffee are represented by galactans, mannans, glucans and arabans. Composition of green coffee polysaccharides agaYsa includes arabinose - 1.8%, galactose - 9.3%, mannose - 20.8%, glucose - 6.8%. At the same time, in roasted coffee and in the extract, these sugars and heteropolysaccharides are present in trace amounts (0.3% glucose, 0.16-0.05% fructose, 0-0.26% mannose and 0.02-0.3% - glucose and sucrose). Thus, during high-temperature processing and under the influence of high pressure (up to 2.5 MPa), cracking processes of destruction, primarily carbohydrates, occur in coffee beans.

In the same time coffee fiber, Constituting one third of the dry matter of coffee beans, it forms the hardness and density of the beans. By preventing coffee from falling apart and expanding in volume during roasting, it allows you to get a flavorful product. At the same time, it is one of the most stable components, and individual types and varieties of coffee practically do not differ from each other in fiber content.

Tannins, contained in coffee determine the astringency of the coffee drink. There is a direct relationship between the content of tannins and chlorogenic acid, which constitutes up to 85-90% of the total amount of polyphenolic compounds. Chlorogenic acid is naturally found in such significant quantities only in coffee beans, giving them a specific slightly acidic and slightly tart taste. The amount of polyphenolic compounds noticeably decreases during storage, which leads to a slight decrease in the astringency of Robusta coffee, but to a poorer taste of coffee drinks made from the highest grades of Arabica. Coffee is characterized by a significant content of caffetannic acid (4-11% dry weight), which is a mixture of chlorogenic, cophalic (C 32 H 38 O ig), cofalic (C 34 H 54 0 15) acids and other compounds.

Titratable acidity is one of its most stably preserved components and, depending on the type of coffee, is 10.8-17.8°. The level of titratable acidity increases slightly as coffee is stored (over 7 years - by 0.3-1.1°), which indicates a slow progression of intracellular hydrolytic and oxidative enzymatic processes.