ABSTRACT
An off-flavor is an atypical odor resulting from degradation of food components, incidental contamination from the environment, and loss of key odorants. Fatty acids constitute an important chemical family of aroma compounds that can contribute to cheesy, rancid, and fatty odors. The volatile short-chain acids, such as pyruvic, acetic, lactic, citric, succinic, and malic acid impart a bitter flavor to beer. Alcohols are synthesized by yeast during fermentation through catabolic and anabolic pathways. The concentration of alcohols is determined by the efficiency of the corresponding amino acid uptake and sugar utilization rate. Acetaldehyde is the main oxidation-related aldehyde identified in alcoholic beverages. This aldehyde may be formed as an enzymatically derived by-product of yeast and acetic bacteria metabolism, or as a non-enzymatic oxidation product of ethanol and phenolic compounds. The moldy taint of wine also recognized as cork taint is due to the presence of chloroanisoles and bromoanisoles.
