Common sense of Fine Coffee beans Chemical composition of coffee

How many substances does a cup of coffee contain? Coffee extracted by traditional methods such as hand-brewing and Syphone contains more than 200 substances, while 1500 qualities can be extracted in an instant when using a Ruyi coffee machine and mocha pot. Unexpectedly, there are so many things in a cup of flavored water, the charm of coffee is made up of these substances.

The chemical composition of coffee beans is quite complex, of which carbohydrates account for the most. Coffee beans contain a variety of carbohydrates, accounting for 60% of the total weight of raw coffee beans, as well as some proteins, fats, tannins, caffeine, minerals and other trace ingredients; and variety, origin and harvest season, will affect the composition of these ingredients. The various ingredients of raw coffee beans will react in the baking process and form the unique flavor and color of all kinds of coffee beans.

1. Caffeine

Caffeine is the most eye-catching of all the ingredients of coffee. It belongs to a kind of phytoxanthine (animal muscle component). It has the same properties as theophylline contained in cocoa, green tea contains the same theophylline, and the percentage of reduction after baking is very small. Caffeine has a very extensive effect. It will affect various parts of the human brain, heart, blood vessels, gastrointestinal tract, muscles and kidneys. The right amount of caffeine will stimulate the cerebral cortex, promote sensory judgment, memory and emotional activity, and make the myocardial machinery more active. Vasodilation enhances blood circulation and improves metabolic function. Caffeine can also reduce muscle fatigue and promote digestive juice secretion. In addition to this, because it also promotes the kidney function to help the body expel excess sodium ions (chemicals that hinder the metabolism of water molecules), caffeine will not accumulate in the body like other narcotic and excitant substances (narcotic drugs, paint solvents, stimulants, etc.) and will be excreted in about two hours. The bitterness of ─, the most important feature of coffee flavor, is caused by caffeine.

2. Tannic acid

After extraction, tannic acid will turn into a yellowish powder, which can easily blend into water. When tannic acid is boiled, it will decompose and produce pyrosylic acid, which will make the coffee taste worse. If you brew it well and leave it for several hours, the color of the coffee will become stronger than when it was first brewed, and it will be less tasty, so there is the saying that "it is best to finish it as soon as possible." Usually a cup of coffee is at its best for 10 minutes. If you want to, you can try whether the taste of the same cup of coffee is the same every minute, and 10 minutes later, the taste of the coffee will be much different from that when it was first brewed.

3. Protein

The protein content of raw beans is about 13%, and the amino acids change differently during baking. Some will react with sugars to form the unique color and smell of baked products. Although coffee beans are rich in protein, but in the brewing process, the protein will not be dissolved out, so no matter how much coffee is drunk, the ingredient is still limited, but the coffee grounds has a high protein content, which is worth reusing.

4. Minerals

Mainly lime, iron, sulfur, sodium carbonate, phosphorus, chlorine, silicon and so on, because the proportion of very little affect the flavor of coffee is not big, combined to bring only a little astringent taste.

5. Sugar

Without sugar, you will not only feel the bitterness of caffeine and the sour taste of tannin, but also feel sweet, which is caused by the sugar contained in the coffee itself. After baking, most of the sugar will be converted to caramel, giving the coffee a unique brown.

6. Volatile components

The aroma of coffee is mainly produced in roasting, and there is no smell of raw coffee beans. When the coffee is first brewed for a moment, the aroma of the room floats, which is equal to half of the coffee already drunk. Coffee aroma is an important feature of its attraction, you can not drink coffee, but can not resist its aroma temptation. The volatile components are the basic elements that bring aroma to the coffee. At present, coffee flavor mixtures are known to contain more than 300 compounds, but most of them are very low. The results of gas chromatography showed that the aroma of coffee was composed of acid, alcohol, acetaldehyde, ketone, ester, sulfur compound, phenol, nitrogen compound and so on. Generally speaking, fat, protein and sugar are important sources of aroma, while lipid ingredients will blend with the sour and bitter of coffee to form a smooth taste. Therefore, the disappearance of fragrance means that the quality is getting worse, and the relationship between aroma and quality is very close.

7. Fat

Raw coffee beans contain about 13% fat. In coffee bean roasting, the fat content will be reduced accordingly, forming part of the volatile components of coffee, which is closely related to the aroma of coffee. During the storage of cooked beans, some chemical reactions such as oxidation and decomposition will occur due to the contact between the fat in the beans and the air, resulting in some compounds with bad smell, which affect the flavor of coffee beans. Therefore, coffee beans in storage, to avoid contact with the air, in order to maintain quality. But it is not good to vacuum, the coffee bean itself will emit some gas, so a better way to preserve it is to put it in a special coffee bag with an one-way exhaust valve.

8. Crude fiber

The fiber of raw beans will be carbonized after baking, which combines with the caramelization of sugar to form the hue of coffee, but the fiber turned into powder will have a considerable impact on the flavor of coffee.

Appendix:

The main chemical constituents of raw coffee beans

Component content (%)

Carbohydrate 60.0

Reducing sugar 1.0

Sucrose 7.0

Pectin 2.0

Starch 10.0

Garrison polysaccharide 5.0

Hemicellulose 15.0

Holocellulose 18.0

Lignin 2.0

Oil 13.0

Protein (Nylon 6.25) 13.0

Ash (oxide) 4.0

Tannic acid 7.0

N-methyl nicotinic acid (soluble) 1.0

Caffeine (soluble) 1.0 mg / kg 2.0