Investigate the Role of Metabolic Cross-feeding Between Starter, Brevibacterium and Nonstarter Cheese Bacteria in the Production or Removal of Aromatic Off Flavor Compounds
Dr. Bart C. Weimer
Brevibacteria don't produce aromatic off flavors from aromatic amino acids. Lactic acid bacteria produce many different compounds. Cross feeding of intermediates between dairy-related bacteria was demonstrated for lactobacilli and brevibacteria. While lactobacilli produce undesirable aromatic off flavors from aromatic amino acids brevibacteria may remove those compounds to compounds that are flavorless or energy during cheese ripening. In some cases this seems to be true, while in other cases, other bacteria, this is not the case. These observations are being verified with cheese from another project that is adding different adjunct bacteria.
B. linens BL2 degrades all the aromatic amino acids. This strain degrades Trp to kynurenine, anthranilic acid, and three unknown aromatic compounds. Kynurenine and anthranilic acid are not associated with known off flavor compounds. Phe is degraded to phenylacetic acid, and Tyr is degraded to non-aromatic compounds. Lactobacilli utilize phenylacetic acid during metabolism. BL2 didn't utilize aromatic off flavors when added to cultures. When added to cheese BL2 significantly improved cheese flavor and did not increase the aromatic off flavors in trained and consumer taste panels. These observations indicate that BL2 is an acceptable adjunct flavor organism for Cheddar cheese.
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Ummadi, M. and B. C. Weimer. Tryptophan metabolism in Brevibacterium linens BL2 (submitted ).
Ummadi, M. and B. C. Weimer. Use of Brevibacterium linens BL2 to reduce off flavor production in Cheddar cheese(submitted ).
Ummadi, M. and B. C. Weimer. 1999. Use of capillary electrophoresis-laser induced fluorescence detection to monitor bacterial growth and amino acid utilization. Electrophoresis (accepted).
M. E. Johnson, J. L. Steele, J. Broadbent, and B. C. Weimer. 1998. Manufacture of gouda and flavour development in reduced-fat cheddar cheese. Aust. J. Dairy Tech. 53:67
Ummadi, M. and B. C. Weimer. 1997. Identification and quantification of tryptophan and its catabolites using Micellar Electrokinetic Capillary Chromatography. High Perfermance Capillary Electrophoresis, Anaheim, CA. Ummadi, M. and B. C. Weimer. 1997. Use of capillary electrophoresis-laser induced fluorescence detection to monitor bacterial growth. High Perfermance Capillary Electrophoresis, Anahiem, CA.
Weimer, B. C., B. Dias, M. Ummadi, M. Stickland, J. Broadbent, M. Johnson, J. Jeaggi, J. Steele, and J. Harper. 1997. Improving Cheddar cheese flavor with the addition of brevibacteria. American Dairy Science Association Annual meeting.
Weimer, B. C., 1997. Strategies for improving cheese flavor. Dairy Management, Inc. Conference on Cheese Flavor. Chicago, IL.
Ummadi, M. and B. C. Weimer. 1998. Aromatic amino acid metabolism
and cheese flavor. Utah Academy of Science.