Aged wine is different from aged wine, because after a long time, a small amount of high-carbon alcohol reacts with esters to generate new fatty acid esters, and different fatty acid esters have different specific smells.
It is also possible that some fresh amorphous or colloidal precipitates gradually transform and crystallize during aging. Such as aging of molecular sieves, hydrated alumina, etc. Is the most typical example of this change. Polymorphic precipitates such as aluminum hydroxide and iron hydroxide usually use different aging conditions to obtain different crystal forms.
The main meaning of grain aging:
Physiological changes: The physiological changes of grain aging, whether with embryo or without embryo, are mainly manifested as changes in enzyme activity and metabolic level. In the process of grain storage, physiological changes are mostly carried out under the action of various enzymes.
If the activity of enzymes in grains is weakened or lost, their physiological functions will also be weakened or stopped. With the aging process, the vitality of grain gradually loses, and the activities of enzymes related to respiration, such as catalase, tend to decrease, and the respiration also weakens. However, the activities of hydrolases such as phytase, protease and phospholipase increased.
1. Changes in chemical composition: The changes in the chemical composition of cereals, whether containing embryos or not, are generally said that the fat changes rapidly, followed by protein, and the starch changes weakly.
2. Changes of fat: In the process of grain storage, free fatty acids first appear in the grain because of the easy hydrolysis of fat. Especially when the environmental conditions are suitable, the stored-grain mold begins to multiply in large quantities, secretes lipase and participates in fat hydrolysis, which increases the fatty acids in grain and deepens the aging degree of grain.