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Aromatic Amino Acid Catabolism By Lactobacillus Spp.: Biochemistry And Contribution To Cheese Flavor Development, Sanjay Gummalla
Aromatic Amino Acid Catabolism By Lactobacillus Spp.: Biochemistry And Contribution To Cheese Flavor Development, Sanjay Gummalla
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Amino acids derived from the degradation of casein in cheese serve as precursors for the generation of desirable and undesirable flavor compounds. Microbial degradation of aromatic amino acids is associated with the formation of aroma compounds that impart putrid-fecal, barny-utensil, and floral off-flavors in cheese, but pathways for their production had not been established. This study investigated Tyr and Phe catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under simulated Cheddar cheese-ripening conditions (pH 5.2, 4% NaCl, 15°C, no sugar). Enzyme assays of cell-free extracts and micellar electrokinetic capillary chromatography of supernatants indicated that L. casei and L. …
Tryptophan Catabolism In Brevibacterium Linens Bl2, Madhavi Ummadi
Tryptophan Catabolism In Brevibacterium Linens Bl2, Madhavi Ummadi
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Recent studies suggest aromatic amino acid catabolism by starter lactococci and flavor adjunct bacteria have a significant impact on off-flavor development during Cheddar cheese ripening. We hypothesized that a flavor adjunct bacterium, Brevibacterium linens BL2, produces off-flavor compounds from aromatic amino acid metabolism that will have a detrimental impact on cheese flavor.
The mechanism of tryptophan (Trp) catabolism in Brevibacterium linens BL2, was investigated in a chemically defined medium during incubation in laboratory conditions (no carbohydrate, pH 6.50, 220 rpm, 25°C) and cheese-like conditions (no carbohydrate, 4% NaCl, static incubation, l5°C). In laboratory conditions, metabolic studies and enzyme assays confirmed …