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Tyrosine And Phenylalanine Catabolism Bylactobacillus Cheese Flavor Adjuncts, S. Gummalla, Jeff Broadbent
Tyrosine And Phenylalanine Catabolism Bylactobacillus Cheese Flavor Adjuncts, S. Gummalla, Jeff Broadbent
Nutrition, Dietetics, and Food Sciences Faculty Publications
Bacterial metabolism of Tyr and Phe has been associated with the formation of aromatic compounds that impart barny-utensil and floral off-flavors in cheese. In an effort to identify possible mechanisms for the origin of these compounds in Cheddar cheese, we investigated Tyr and Phe catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under simulated Cheddar cheese-ripening (pH 5.2, 4% NaCl, 15°C, no sugar) conditions. Enzyme assays of cell-free extracts indicated that L. casei strains catabolize Tyr and Phe by successive, constitutively expressed transamination and dehydrogenation reactions. Similar results were obtained with L. helveticus strains, except that the dehydrogenase …