CITRATE METABOLISM IN LACTIC-ACID BACTERIA

Citrate metabolism plays an important role in many food fermentations involving lactic acid bacteria. Since citrate is a highly oxidized sub strate, no reducing equivalents are produced during its degradation, r esulting in the formation of metabolic end products other than lactic acid. Some of these end products, such as diacetyl and acetaldehyde, h ave very distinct aroma properties and contribute significantly to the quality of the fermented foods. In this review the metabolic pathways involved in product formation from citrate are described, the bioener getic consequences of this metabolism for the lactic acid bacteria are discussed and detailed information on some key enzymes in the citrate metabolism is presented. The combined knowledge is used for devising strategies to avoid, control or improve product formation from citrate .