Which fermentation type is characterized by the production of lactic acid and ethanol/CO2?

Heterolactic fermentation is characterized by the production of both lactic acid and ethanol, along with carbon dioxide. This type of fermentation occurs in certain bacteria, particularly those in the Lactobacillus genus. During the process, pyruvate is converted into lactic acid, ethanol, and CO2, resulting in a mixed fermentation product profile.

Heterolactic fermentation is distinct from homolactic fermentation, where only lactic acid is produced, and from alcoholic fermentation, which primarily yields ethanol and CO2 without lactic acid. Malolactic fermentation, commonly involved in winemaking, refers specifically to the conversion of malic acid to lactic acid and is primarily associated with the softening of acidity in wines rather than the production of ethanol or CO2. Thus, the identification of heterolactic fermentation as the correct answer highlights its unique ability to produce both lactic acid and fermentation by-products like ethanol and carbon dioxide.