What is the primary difference between heterolactic and homolactic fermentation?

The primary difference between heterolactic and homolactic fermentation lies in the metabolic end products generated during the fermentation process. Homolactic fermentation is characterized by the conversion of glucose primarily into lactic acid. Organisms that undergo this type of fermentation, such as certain lactic acid bacteria, predominantly produce lactic acid as the sole or main byproduct.

In contrast, heterolactic fermentation produces not only lactic acid but also other byproducts such as ethanol and carbon dioxide. This occurs in some strains of lactic acid bacteria that can metabolize glucose via the pentose phosphate pathway, leading to a mix of end products.

The statement that homolactic fermentation only produces lactic acid correctly identifies the unique aspect of this specific fermentation pathway. This distinction is essential for understanding various fermentation processes, especially when considering the implications for flavors, aromas, and texture in fermented beverages or foods.