The bitterness and mellowness of coffee.

Coffee's color, aroma, and taste are the result of complex chemical changes that occur through the roasting process. Therefore, raw beans must undergo appropriate chemical procedures to achieve the most balanced state of its essential ingredients in order to be considered the best baked beans. Coffee aroma changes with heat, so roast time should be as short as possible, and heat control can make coffee beans produce effective chemical composition of the minimum temperature, that is, the shortest process time and heat, so that coffee beans produce the most suitable composition ratio.

Aroma is the life of coffee quality, but also the best performance of coffee production process and roasting technology, production climate, elevation, variety, refining treatment, harvest, storage, consumer country roasting technology is appropriate, etc., are the conditions that control coffee bean aroma. The aroma of coffee was proved to be composed of hundreds of volatile components such as acids, alcohols, aldehydes, ketones, esters, sulfur compounds, phenols and nitrogen compounds. Roughly speaking, fat, protein, and sugar are important sources of aroma, while lipid components will blend with the bitterness and sourness of coffee to form a smooth taste. Therefore, the disappearance of aroma means that the quality is poor, and the relationship between aroma and quality is extremely close.

The basic taste of bitter coffee is the bitter strength and bitter texture. The raw beans contain only a very small amount of bitter ingredients, and then the caramelization and carbonization of sugar, part of starch and fiber caused by roasting produce the most symbolic bitter taste of coffee. Caffeine, one of the bitter components, is also an important substance that shows the pharmacological characteristics of coffee. The content varies according to its type, refinement and roasting degree. If the roasting temperature is high, the content will decrease. Therefore, the lighter the roasting, the stronger the pharmacological effect of caffeine, and the weaker the roasting. Generally speaking, the coffee with strong sour taste will be weak in bitterness, while the coffee with bitter taste as the main body is easy to appear insufficient in sourness, so the proportion of sour and bitter gives coffee a space for development in taste. Bitterness mainly depends on the roasting time and the strength of the fire, whether the fire is appropriate or not, but it will also be affected by the brewing temperature and brewing time, so the coffee bitter taste that wants to be brewed is advanced and refreshing. In addition to the good quality of raw beans, it is more necessary to have rich knowledge and technology from roasting to brewing.

Acidity is certainly affected by the quality and variety of green beans. In terms of variety elevation, coffee grown in the high ground is more acidic than coffee grown in the low ground, and beans freshly harvested are more acidic than beans aged for a while. Different types of acid, its increase and decrease changes are also different, generally lighter baked beans, sour more abundant, baked deeper, sour more scarce. Freshly harvested beans, good quality, high moisture content, if the appropriate heat to produce moderate sour, will make coffee taste better, let people feel more depth.

Strong alcohol and sweet generally we use strong alcohol to express coffee ripe, aromatic alcohol, strong taste. The unique sweetness of high-grade coffee is related to bitterness, so the refreshing taste of the superior taste must be sweet. During baking, some of the carbohydrates such as sucrose and glucose caramelize, and the rest form a sweet taste, a moderately sweet product that is easily lost during baking and brewing if heat treatment is excessive.