Detailed Analysis of the components of High-quality Coffee beans

★ Volatile substances:

Volatiles are the main source of coffee flavor and are especially important for coffee quality. There are many kinds of volatile compounds in coffee, and their existence will affect the aroma quality of coffee. The main source is derived from non-volatile substances from raw beans, which are broken off or reacted during roasting. Thermal decomposition, other reactions or interactions between components, such as carbohydrates, amino acids, organic acids and phenolic compounds, form coffee's unique aroma and flavor. The factors affecting the volatile components of coffee include: coffee bean varieties, cultivation climate, soil conditions, storage of green beans, roasting temperature and time, roasting equipment and other factors.

Raw coffee beans do not contain the special aroma of coffee, so they are not eaten directly. They must be roasted before they generate a large number of volatile aroma substances. After roasting, the main volatile aroma components of raw coffee beans were analyzed and confirmed to have at least 660 kinds, which was the most volatile aroma components in all foods and beverages. The aroma generated in the roasting process, such as hazelnut flavor, cream flavor and caramel flavor, or grassy flavor, smoky flavor, burnt flavor, spicy flavor and bitter flavor, mostly came from volatile substances. The difference of roasting degree would also affect the flavor characteristics of coffee.

★ Pectin and lignin:

Pectin is composed of a variety of polysaccharides. Its main components are galactonic acid polymer, aronic acid and rhamnose, etc., and its content is more than 3%. Lignin is the insoluble residue remaining after the treatment of plants with sulfuric acid and caustic, that is, the so-called coffee fiber, and its content is about 2.4%.

★ Nitrogen compounds:

The nitrogen-containing compounds contained in green coffee beans can be divided into phytoalkaloids, Trigonelline, nicotinic acid, protein and free amino acids, etc., as follows:

★ Alkaloids:

Caffeine is mainly used, and the content of caffeine in green coffee beans varies greatly due to different varieties. Robusta content is higher, about 2.2%, Arabica content is lower, about 1.2%. In Java and Cote d'Ivoire, low-caffeine coffee beans have been cultivated in recent years, with a caffeine content of only 0.2%. Caffeine can be removed by a variety of methods to make a variety of decaffeinated products, decaffeinated instant coffee powder caffeine content of 0.3%, general commodities are controlled between 0.1%~ 0.2%. Caffeine is arguably the spirit of coffee and the most controversial issue.

Caffeine, although not odorous, has a pronounced bitter taste. Although some people have tried to use the bitterness of coffee to judge the amount of caffeine content, they have not been completely successful because caffeine bitterness accounts for only a small part of coffee bitterness, so it does not have much influence on decaffeinated coffee bitterness.

After caffeine is digested by the body, it is rapidly absorbed and metabolized and excreted in urine. Caffeine in the human blood content increased status, according to the stomach content may be. The most significant physiological effect of caffeine on the human body is the stimulation of the central nervous system. As for the changes in brain activity, the dose required is extremely high, which is much higher than the normal intake. Other physiological effects that attract more attention are the influence on blood pressure and heart vessels.

Trigonelline:

Trigonelline is a hygroscopic colorless crystal with excellent solubility in water. It also has a low degree of physiological effects, mainly for the central nervous system, bile secretion and intestinal motility.

Trigonelline directly on the quality of coffee caused by the impact is very small, its bitterness is only a quarter of caffeine, due to its presence in small quantities, so the impact on taste is not very large. The content in green coffee beans varies according to the variety, Arabica content is higher than Robusta. Trigonelline is rapidly decomposed during roasting, with a loss rate of about 50 - 80%, depending on the roasting temperature and time. Trigonelline decomposes into a variety of compounds, including non-volatile nicotinic acid, etc., and 29 volatile substances, 9 of which have been identified as pregnant coffee aroma substances.

★ Nicotinic acid:

Nicotinic acid in green coffee beans content is very small, but after roasting, there is an increase in the phenomenon, the main reason is that it comes from trigonelline decomposition results. But the study found that niacin continued to break down into volatile chemicals at the high temperatures of roasting, so the real increase was small.