Acetaldehyde is usually the major carbonyl compound in distilled beverages. The formation of acetals reduces the content of free aldehydes in distillates; consequently, the acetals formed can smooth down the pungent odor caused by aldehydes. Distilled beverages may contain fairly large amounts of aliphatic alcohols called fusel alcohols. A sharp or raw odor typical of fresh distillates may be modified by storing the distillate in oak barrels. Most of the acids present in distilled beverages are common monocarboxylic acids formed during fermentation. The formation of acetals reduces the content of free aldehydes in distillates. The presence of oxygen in fermentation has a significant effect on the formation of esters. The results show firmly that different yeasts can produce varying amounts of flavor compounds under different fermentation conditions, and, therefore, selecting the yeast for the manufacturing of distilled beverages is of great significance.