What does the coffee bean consist of, caffeine and. Composition of coffee. What's in coffee? Vitamins and minerals in the chemical composition of coffee

Why do we love coffee? The answer to this question is quite obvious - some people need its invigorating effect, while others enjoy the taste and aroma. At the same time, few people think about what substances are contained in the grains from which it is prepared. The only thing we know is that caffeine wakes us up in the morning and helps us function during the day. However, this is not the only substance found in coffee beans.

The composition of this product is so rich that it is even surprising why the drink that is prepared from it can equally bring both benefit and harm. With the right approach, coffee can become not only a surprisingly tasty energy drink, but also, to some extent, a cure for many diseases. Or at least help prevent them.

It’s worth mentioning right away that coffee beans do not have a stable composition. It depends on the variety, place of growth, time of collection and other important points. It also changes when raw materials contain several hundred chemical compounds, but in the finished product this figure can only reach two thousand. Surprisingly, despite all the progress that scientists have made in chemistry, it is still not possible to recreate at least something similar to natural grain. very far from what can be considered a real drink.

For the most part they consist of carbohydrates - they account for about half of the total mass. When fried, the amount of some of them decreases, and sucrose turns into caramel. It is responsible for the brown color of the future coffee drink. Also, during the heat treatment, a substance called kafeol is formed, which gives the specific aroma of coffee.

Another element on which the specific taste and aroma of the finished drink depends is trigonelline, which belongs to the group of alkaloids. It is he, and not caffeine, as we are accustomed to believe, that is responsible for the taste and aroma component. The latter is also an alkaloid and has a tonic property. Yes, in its pure form, caffeine has a bitter taste, but this does not affect the coffee drink in any way. The same substance can be found in Coca-Cola - a couple of bottles are comparable in effect to a cup of natural coffee. The taste is completely different.

The taste of the future drink is also influenced by a chemical substance such as tannin. First of all, it is responsible for binding polysaccharides and proteins. In green grains, the percentage of the substance is about seven percent. When roasting, it is destroyed, but this is what gives the grain its unique taste and aroma. It turns out that the destruction of tannin is a necessary condition for creating the coffee drink that we know and love.

Another important substance that coffee contains is protein. Its amount is about 10% of the total amount of all substances.

Speaking about the chemical composition of grains, do not forget about vitamins and minerals, of which there are also a lot. What is really abundant here is vitamin B3. This substance affects metabolism in the body. In addition to B3, coffee also contains other important microelements. Here are just a few of them:

vitamins A, E, almost the entire group B, PP;
iron;
sodium;
calcium;
magnesium;
zinc;
copper.

As mentioned above, the chemical composition of grains can change under the influence of many conditions. But even the lowest grades of coffee beans contain many substances and their compounds. So we can safely say that the drink, so beloved by many, can be good for health, naturally, if consumed correctly.

Those who have problems with the cardiovascular and nervous systems, gastritis, ulcers, and rectal diseases should not drink coffee.

In addition, excessive consumption of this invigorating drink can lead to insomnia, nervousness, and irritability. If you don’t get carried away and take into account the state of your health, then coffee will not cause any harm.

What can you say about instant drinks?

Manufacturers are constantly working to improve the composition of instant coffee. But so far it is very far from natural grain. In the best case, the substances that are present in coffee beans in powder will account for no more than 20% of the total amount. Everything else is flavorings, preservatives, dyes and other achievements of the chemical industry.

True, in stores you can find instant coffee labeled “organic”. This powder will not contain any artificial additives, only coffee extract. Accordingly, the price of such powder will be significantly higher. True, this guarantees only a natural composition, pleasant taste and aroma.

But the chemical composition of an instant drink, even an organic one, is much poorer than that of its grain counterpart. Such valuable proteins, carbohydrates, amino acids and vitamins are present here, if present, then in small quantities. What cannot be taken away from instant coffee is the ease of brewing and long life. But is it really worth giving up the pleasure of drinking a cup of aromatic, tasty, and most importantly, natural drink?

photo: depositphotos.com/jirkaejc, Julia_Arda, muha04

The taste of coffee depends on the variety, quality, growing conditions and processing of coffee beans. Four types of coffee are grown commercially: Arabica, Robusta, Liberica and Excelsa. The most delicious and aromatic, and therefore the most expensive, is Arabica. True, recently new varieties have appeared from the so-called “Ethiopian heritage” - wild varieties of coffee. They are considered promising, but the best of them, for example, Geisha, come from Arabica.

The fruits of the coffee tree are called berries (in the English tradition - cherries). All types of coffee berries have the same structure and differ from each other only in size, thickness of the peel or parchment shell, and color.

The berry most often contains 2 grains. Ripe berries, depending on the type of coffee tree, turn red or yellow. As the pulp matures, it acquires an increasingly sweeter taste. The pulp contains caffeine (although it is much less than the beans), and it produces an invigorating drink - cascara.

Structure of a coffee berry:

The outer shell of the berry is the peel.
Under the skin there is pulp (pulp).
A layer of gluten separates the pulp from the grain shells. While the berries are green, this layer is hard, but as they ripen, it softens and becomes very sticky.
Under the gluten there is a dense parchment shell.
The coffee bean is surrounded by a thin, silvery shell that peels off during roasting.

The grain ripens together with the pulp, feeds on the beneficial substances contained in it, and acquires sweetness. Therefore, grains only from ripened berries are valued. If the berries are not ripe or overripe, the grains are classified as defective.

Peaberry coffee

As a result of mutation, up to 5% of coffee berries contain not two, but only one grain, called (peaberry in English - “pea”). Sometimes it is mistakenly believed that it consists of two grains fused together. This is not true: when two grains grow together, they form a hollow ball that can easily be divided into two concave halves. Such grains are considered defective, the defect is called “elephant ears”.

The process of creating a peaberry is completely different. A normal ovary always contains two tiny grains. However, in mutated berries, the development of one grain stops, but the other increases significantly in size: after all, it receives all the nutrients that nature provided for the two seeds.

Coffee brewed from peaberry has a brighter taste and intense aroma. In Western Europe, the USA and Australia, cafes designed for gourmets are opening, where coffee is prepared exclusively from peaberry.

It has been noted that most peaberry is formed on plantations where mineral fertilizers are not used. For example, in Tanzania up to 10% of Arabica is peaberry. Taking advantage of the high value of unusual coffee, Tanzanian farmers hand-select Peaberry beans and sell them at a much higher price than regular Arabica.

In Latin America, peaberry is called caracol ("snail") or perla (pearl). Thanks to the use of modern technologies, 2-3 tons of coffee are harvested here from one hectare (while in Tanzania - 300 kg). Therefore, Latin American farmers often see no point in manually sorting the coffee to separate the peaberries.

Chemical composition of coffee beans

Coffee beans contain more than 100 chemical compounds. Many of them decompose during roasting, forming substances that affect the taste and aroma of coffee.

Substances that affect the properties of coffee as a drink:

caffeine is an alkaloid that acts as an energy drink. Robusta has more caffeine than Arabica;
trigonelline is an alkaloid that, when heated, is destroyed to form nicotinic acid. Trigonelline breakdown products react to form substances that create a pleasant aroma of roasted grains;
carbohydrates, in particular monosaccharides (glucose, fructose, lactose, sucrose), which give the drink a sweet taste. Arabica contains 8.2–8.3% sugars, and Robusta contains 3.3–4.1%. The brown color of roasted coffee beans is a consequence of caramelization of sugars during heat treatment;
fats - when heated, decompose, forming acids. It is due to the presence of fats that roasted coffee acquires a rancid smell during long-term storage. It is believed that Indian Arabica coffee contains the least amount of fat;
organic acids: citric, tartaric, malic, oxalic, caffeic. Fruit acids give the drink sourness: citrus or berry, sometimes with wine notes. If there is an unpleasant taste of vinegar in the drink, it means that the grains have been fermented for too long, which is why acetic acid has formed in them. This taste is considered a disadvantage. Acids decompose when heated, so there is practically no sourness felt in dark roasted coffee. If you want to tone down the sourness in light roast coffee, you need to prepare the drink in a pour over or brew it using the cold brew method;
chlorogenic acid (refers to organic acids), which itself does not have a bitter taste. When roasted, it forms chlorogenic acid lactones, which in turn decompose into phenylindanes, which are very bitter substances. Therefore, coffee made from dark roasted beans is always more bitter;
tannins are compounds that give the drink a bitter-tart taste.

Dependence of coffee taste on climatic conditions

The taste of coffee of the same variety varies depending on the altitude at which the plantation is located:

600–1200 m – sometimes there are hints of earth and grass in the taste, especially if the grains are dry processed. When processed wet, the taste becomes more pleasant;
1200–1800 m – coffee has a nutty, citrus or vanilla-chocolate flavor;
above 1800 m – floral, berry, fruity shades appear in the taste, sometimes with wine sourness.

High mountain coffee is considered the best. However, harvesting is not easy: the plantations are located in places with difficult terrain, on mountain slopes, where it is impossible to deliver equipment. Therefore, such coffee is collected by hand and processed especially carefully, otherwise it cannot be sold at a high price.

Coffee bean sizes

To sort grains, they are sifted through special sieves with cells of different sizes.

Types of coffee by bean size (green, unroasted beans are measured):

very fine grain (sieve No. 12, mesh side length - 4.764 mm);
fine grain (No. 13, 5.161 mm);
small grain (No. 14, 5.558 mm);
medium grain (No. 15, 5.955 mm);
good grain (No. 16, 6.352 mm);
sufficiently large grain (sieve No. 17, 6.749 mm);
large grain (No. 18, 7.146 mm);
extra large grain (No. 19, 7.543 mm);
very large grain (No. 20, more than 8 mm).

The size of the coffee bean does not directly affect the taste of the drink; not a single modern quality assessment system considers size as a criterion. Sorting is only needed for correct . The larger the grain, the more difficult it is to roast it evenly inside and out.

Defects in coffee beans

If the beans are improperly processed or stored in improper conditions, the drink will have an unpleasant taste and aroma. To determine quality, weigh 300 g of coffee and count the number of beans with defects.

Types of defects in coffee beans:

black grains affected by fungus (give the drink an unpleasant taste);
grains with holes damaged by insects;
concave grains of irregular shape, resembling shells. As a rule, they have low acidity;
oily grains. The defect occurs due to low iron content in the soil. The taste of the drink will be mild;
Quakers are shriveled grains from unripe berries. The coffee is bitter, the sourness is almost not felt;
rust-colored grains obtained from berries that are overripe or have been fermented for too long. The drink has an acetic acid taste;
broken, cut grains often smell bad;
grains covered with mold;
wrinkled yellow grains that have been dried for too long;
fragile (crystallized) grains of bluish-gray color. This appearance occurs due to too high a drying temperature. The coffee they make tasteless.

Foreign inclusions are also considered defects: pebbles, leaves, coffee husks.

Julia Vern 37 775 2

Coffee is one of the few drinks of natural origin, consisting of a huge range of different substances, both organic and inorganic, that significantly affect almost all structures and systems of the human body.

Freshly brewed coffee without sugar contains about 1,200 natural components, more than half of which are aromatic compounds that determine the taste of the drink.

The taste of the drink is determined by the huge number of volatile compounds included in its composition.

Chemical composition of coffee

Caffeine belong to the group of alkaloids that stimulate the activity of the central nervous system. For the first time, caffeine was obtained from coffee beans, which is why it got its name. The drink owes its tonic effect, increasing mental and physical performance, to caffeine.

According to modern requirements, when making coffee, there must be at least 0.7% caffeine in it, which directly depends on the degree of ripening of the coffee beans and their roasting.

At this concentration, one teaspoon of freshly ground natural coffee will contain 0.1-0.2 grams of pure caffeine, which is quite enough to obtain the appropriate tonic effect.

It is not recommended to exceed the dose of caffeine above 0.3 grams at a time for 3-4 hours - regular excess of the dosage stimulates the manifestation of increased excitability, sleep disturbances, and increased heart function.

Trigonelline- an alkaloid, in its pure form, tasteless and odorless, but during heat treatment it is converted into pyridine - a substance that gives coffee a specific aroma. Another striking chemical property of trigonelline is its close chemical relationship with nicotinic acid (vitamin B3). The nicotinic acid molecule is part of trigonelline and is easily released when heated, which ensures a constant amount of vitamin B3 in the drink.

Vitamin B3 plays a vital role in metabolism in the body, stimulates the activity of the nervous system. A lack of this vitamin leads to a disease such as pellagra.

A nicotinic acid is not the only B vitamin found in coffee beans. After appropriate processing of natural coffee, the drink contains the entire palette of vitamins of this group, as well as:

the mandatory presence of vitamin A, which is involved in growth and development;
vitamin D, which improves the absorption of calcium and phosphorus in the intestine;
vitamin E, which is a participant in the reproduction process and a stimulator of the immune system.

Coffee contains a significant amount of complex organic compounds. This proteins and amino acids, performing nutritional and energy functions for the cells of the body. Coffee beans are one of the rare plant products that contain essential amino acids that the body gets from meat and fish. Such amino acids are not synthesized in the human body and participate in the restorative functions of cellular mechanisms and maintain immunity at a fairly high level.

Caffeine molecule structure

Overall volume carbohydrates in raw coffee beans makes up about 50% of its mass. These energetically valuable substances for the body are represented by both simple sugars - sucrose and fructose, and complex polysaccharides - cellulose, fiber, pectin substances, which represent an indispensable basis for the nutrition of nerve cells of the brain.

Mineral substances in coffee include: potassium, magnesium and calcium. These inorganic elements make up bones, ensure muscle function, and regulate the functioning of the heart, blood vessels and brain.

Raw coffee beans contain about 850 different essential compounds, and roasted coffee beans contain about 350, which is why coffee has deservedly been awarded the title of the most fragrant drink.

Nutritional value of coffee

Despite such a diverse composition, coffee made from freshly ground natural beans does not have such a high calorie content, which is due to the easy digestibility of the substances included in its composition. The process of absorption and digestion is further stimulated by caffeine, which is also known to be contained in coffee drinks.

Depending on the type of coffee and the method of its preparation, its nutritional value per 100 grams of sugar-free product is on average:

proteins, all types - 0.2 g,
fats - 0.6 g,
carbohydrates - 0.1 g,
calcium - up to 5 mg,
vitamin B3 - 0.6 mg,
potassium - 9 mg,
phosphorus - 7 mg,
iron - 2 mg.

Coffee can have both positive and negative effects on the human body.

The effect of coffee on human health

Given its rich chemical composition, coffee has both beneficial and negative effects, which directly depends on the individual characteristics of a person and the volume of drink consumed per day. The general picture of the effect of a coffee product on the body is as follows:

regular intake of pure caffeine in an amount of more than 1000 mg, which coffee is richest in, can cause the phenomenon of addiction, similar to drugs or alcohol;
coffee has a sufficient diuretic effect, so if signs of dehydration appear, it is necessary to increase the amount of fluid you drink;
In healthy people who do not suffer from high blood pressure, coffee causes a general increase in pressure by 10-15 mmHg. In people suffering from hypertension and related cardiovascular diseases, blood pressure can increase much more strongly or, conversely, decrease, which greatly limits their ability to drink coffee;
There is no direct effect of caffeine on the heart. Coffee acts on cardiac activity indirectly - increasing blood pressure through a stimulating effect on the central nervous system;
regular use of unfiltered coffee often leads to an increase in total cholesterol in the blood, which inevitably leads to vascular pathologies, characterizing the appearance of problems with blood pressure;
improvement in attention, productivity, memory and mood is a temporary phenomenon. Depending on the reactivity of the body, this effect disappears after 30-120 minutes;
coffee enhances the effect of some painkillers, for example, acetylsalicylic acid and analgin, reduces the risk of Parkinson’s and Alzheimer’s diseases due to a temporary vasoconstrictor effect and a direct effect on the neurons of the brain, the so-called “training” effect of these organs occurs;
Regular consumption of coffee reduces the risk of developing constipation and cirrhosis of the liver, breast cancer in women;
in older people, coffee reduces the density of skeletal bones, which can cause cracks and fractures;
people who drink more than two cups of coffee a day have a high risk of developing urolithiasis;
Pregnant women are not recommended to drink more than a cup of coffee per day. Due to the increase in blood pressure due to the effects of caffeine, placental anemia, premature birth and low birth weight of the newborn, as well as miscarriages and stillbirths, are possible.

Advantages and disadvantages of instant coffee

The production of instant coffee involves boiling coffee beans, obtaining a coffee drink and then drying it. In this case, there is an intensive release of all the soluble elements contained in the coffee beans and their re-placement into the finished mass of soluble substance, which cannot but be accompanied by losses. Therefore, the main disadvantage of instant coffee is the loss of some valuable nutrients (vitamins, essential amino acids, proteins) and the weakening of the aroma due to the evaporation of essential oils. Also, instant coffee has a more obvious bitter taste.

Instant coffee contains fewer nutrients than ground coffee

Manufacturers try to compensate for losses by adding these substances to the finished product, which inevitably leads to higher prices. Therefore, the cheaper the coffee on the counter, the poorer its taste and aroma. In addition, in the production of instant coffee, waste from the production of natural coffee is used, more often from discarded beans.

Perhaps the only advantage of instant coffee is the speed of preparation and the increase in its shelf life.

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.

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. In its pure form, caffeine was isolated 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.