New Starter Systems for Accelerated Ripened Cheddar Cheese

Principal Investigator:

Dr. Jeff Broadbent

Co-Investigators:

Dr. Charlotte Brennand, Utah State University

Drs. James Steele and Mark Johnson, University of Wisconsin-Madison

Project Summary:

Bitterness is a significant concern in accelerated ripened cheese. It is our hypothesis that the most effective strategy to control bitterness and over-ripening by proteolysis in accelerated ripened cheese is to develop a starter system that combines a low propensity for the production bitter peptides with high debittering peptidase activity. A key advantage to this approach is that is will not only help to retard over-ripening by proteolysis (via control over bitterness), it will also boost (via the production of free amino acids) levels of cheese flavor precursors in the curd matrix. Our group has shown that the starter proteinase is a key determinant in the production of bitter peptides, and that we can increase the activity of enzymes that degrade bitter peptides up to 1000-fold using a starter-based enzyme delivery system. This project will provide industry with information and technology transfer tools to develop food grade starter systems that control bitterness and over ripening in accelerated ripened cheese.

Publications:

Christensen, J. E., J. R. Broadbent, and J. L. Steele. Hydrolysis of casein derived peptides aS1-CN (f1-9) and b-CN (f193-209) by Lactobacillus helveticus peptidase deletion mutants indicates the presence of a previously undetected endopeptidase. Appl. Environ. Microbiol. (accepted for publication).

Chen, Y.-S., J. E. Christensen, J. R. Broadbent, and J. L. Steele Identification and characterization of Lactobacillus helveticus PepO2, an endopeptidase with post-proline specificity. Appl. Environ. Microbiol. (accepted for publication).

Broadbent, J. R., M. Barnes, C. Brennand, M. Strickland, K. Houck, M. E. Johnson, and J. L. Steele. 2002. Contribution of Lactococcus lactis cell envelope proteinase specificity to peptide accumulation and bitterness in reduced-fat Cheddar cheese. Appl. Environ. Microbiol. 68:1778-1785.

Strickland, M., M. E. Johnson, and J. R. Broadbent. 2001. Qualitative and quantitative analysis of proteins and peptides in milk products by capillary electrophoresis. Electrophoresis 22:1510-1517.

Theses:

Chen, Y.S. 2001. Endopeptidases of Lactobacillus helveticus CNRZ32: Identification and Characterization. Ph.D. Dissertation, University of Wisconsin-Madison.

Christensen, J.E. 2000. Peptidases of Lactobacillus helveticus: role in physiology and caein hydrolysis. Ph.D. Dissertation, University of Wisconsin-Madison.

Published Abstract:

None

Presentations:

Sridhar, V.R., V.V. Smeianov and J.L. Steele. 2002. Construction and evaluation of food-grade vectors for Lactococcus lactis using aspartate aminotransferase and alpha-galactosidase as selectable markers. 2002 ADSA annual meeting abstract submitted.

Brennand, C. P., and J. R. Broadbent. 2001. Use of sensory methods in a molecular-genetic study of bitterness in Cheddar cheese. Invited oral presentation for the Symposium on Sensory Evaluation of Dairy Flavors at the Ann. Mtg of the Institute for Food Technologists. June 23-27, New Orleans, LA.

Chen, Y. C., J. E. Christensen, M. Strickland, and J. L. Steele. 2001. Identification and characterization of endopeptidase O2 from Lactobacillus helveticus CNRZ32, an enzyme involved in the hydrolysis of a b-casein derived bitter peptide. Oral presentation at the Ann. Mtg of the Institute for Food Technologists. June 23-27, New Orleans, LA.

Broadbent, J.R. 2000. Role of lactic acid bacteria in cheese flavor development -Part I. Invited oral presentation for special ADSA pre-meeting workshop on the basics of flavor development in cheese. Sponsored by the American Dairy Science Association and Rhodia, Inc. July 24, Baltimore, MD.

Steele, J.L. 2000. Role of lactic acid bacteria in cheese flavor development -Part II. Invited oral presentation for special ADSA pre-meeting workshop on the basics of flavor development in cheese. Sponsored by the American Dairy Science Association and Rhodia, Inc. July 24, Baltimore, MD.

Chen, Y.-S., J.E. Christensen and J.L. Steele. 2000. Identification and characterization of PepO2 from Lactobacillus helveticus CNRZ32, an enzyme involved in the hydrolysis of a ?-casein derived bitter peptides. Oral presentation at the 2000 annual meeting of the American Dairy Science Association.

Steele, J.L. 1999. Peptidases and amino acid catabolism. Invited oral presentation for the symposium on Dairy Flavors and Biotechnology. IFT Annual Meeting, July.

Steele, J.L. 1999. Peptidases and amino acid catabolism. Invited oral presentation for the Sixth Symposium on Lactic Acid Bacteria. September, The Netherlands.

Broadbent, J.R. 1999. Cheese curing and flavor development. Invited oral presentation for the 15th Cheese Making Short Course. February 9-11, Utah State University, Logan.