Why is wine spicy?

Aldehydes are the main substances that cause the spicy taste of liquor. Such as furfural, acetaldehyde, acetal, acrolein, crotonaldehyde and tert-butanol, tert-amyl alcohol, acetone and ethyl formate; Ethyl acetate and other substances. The main reasons for the spicy taste are: too much auxiliary material (such as chaff) is used in production without steaming, which makes pentosan in it generate a lot of furfural after heating in brewing, which makes the wine produce bran flavor and dry spicy taste. B fermentation temperature is too high; Poor operating conditions lead to poor saccharification, and mixed grain is infected with miscellaneous bacteria, especially abnormal fermentation caused by glyceraldehyde and acrolein produced by lactic acid bacteria. C the fermentation speed is unbalanced, the front fire is fierce, the mouthparts come quickly and fiercely, and the premature aging and death of yeast cause abnormal fermentation, which leads to incomplete fermentation of yeast alcohol and more acetaldehyde. D during distillation, the fire (steam) is too small, the temperature of the flowing wine is too low, and the low-boiling substances are not effectively volatilized. E. insufficient storage time for ripening.