Project Title: Effects of Microbial Exopolysaccharide on Functionality in High Moisture Cheese

Principal Investigator:

Dr. Jeff Broadbent

Co-Investigators:

Dr. Donald J. McMahon, Utah State University
Dr. Craig J. Oberg, Weber State University

Project Summary:

The objectives of this study were to determine if the addition of Streptococcus thermopnilus MR-1C, a strain that produces a large capsular exopolysaccharide (EPS), to cheese can be used to improve shreddability, as measured by firmness, in high moisture American style cheese. Functional attributes of cheese such as shreddability and melt are dramatically affected by cheese moisture level. Previous work at Utah State University has demonstrated that: i) cheese moisture content is related to the water binding capacity of the curd matrix; ii) addition of MR-1C to cheese results in a significant increase in cheese moisture level; iii) this effect is due exclusively to the water-binding properties of the MR-1C capsular exopolysaccharide; and iv) use of MR-1C in cheese manufacture does not have a detrimental effect on whey viscosity. To determine whether the MR-1C EPS can be used to improve cheese firmness, we manufactured stirred curd cheeses with equivalent moisture levels (42%) using either the S. thermophilus MR-1C or a non EPS-producing adjunct. The suitability of individual cheeses for shredding was determined using rheometry and texture profile analysis. The firmness of each cheese was determined after 1, 3, and 6 wks of aging, then the cheese was shredded, 3% (wt/wt) powdered cellulose was added to prevent caking, then the cheese was packaged with a nitrogen gas flush, and melt properties were measured periodically over 24 wks. Unfortunately, statistical analysis showed there were no significant differences in viscosity/elasticity, hardness, or meltability of cheeses made with or without the EPS-producing culture.

Publications:

Broadbent, J. R., D. J. McMahon, D. Welker, C. J. Oberg, and S. Moineau. 2002. Biochemistry, genetics, and applications of exopolysaccharide production in Streptococcus thermophilus: a review. J. Dairy Sci. (accepted for publication).

Broadbent, J. R., D. J. McMahon, C. J. Oberg, and D. L. Welker. 2001. Use of exopolysaccharide-producing cultures to improve the functionality of low fat cheese. Int. Dairy J. 11:433-439

Petersen, B. L., R. I. Dave, D. J. McMahon, C. J. Oberg, and J. R. Broadbent. 2000. Influence of capsular and ropy exopolysaccharide-producing Streptococcus thermophilus on Mozzarella cheese and cheese whey. J. Dairy Sci. 83:1952-1956.

Theses:

Petersen, B. L. 2001. Biochemistry and application of exopolysaccharide production in Mozzarella cheese starter cultures. MS thesis, Utah State University, Logan.

Published Abstract:

Oberg, C.J., J.R. Broadbent, and D.J. McMahon. 2002. Applications of EPS production by lactic acid bacteria. J. Dairy Sci. 85(Supp. 1):116.

Singleton, T. J., D. J. McMahon and J. R. Broadbent. 2001. Effect of microbial exopolysaccharide on functionality in high moisture cheese. J. Dairy Sci. 84(Supp. 1):147

Presentations:

Oberg, C.J., J.R. Broadbent, and D.J. McMahon. 2002. Applications of EPS production by lactic acid bacteria. Invited oral presentation for the symposium on exopolysaccharide production by lactic acid bacteria at the annual meeting of the American Dairy Science Association. July 21-25, Quebec City, Quebec, Canada.

Singleton, T. J., D. J. McMahon and J. R. Broadbent. 2001. Effect of microbial exopolysaccharide on functionality in high moisture cheese. Oral presentation at the 96th Annual meeting of the American Dairy Science Association. July 24-28, Indianappolis, IN.

Broadbent, J. R. 2001. Exopolysaccharide production in Streptococcus thermophilus: biochemistry, genetics, and applications. Invited oral presentation for Fifth Annual Symposium on Industrial and Fermentation Microbiology. April 27, University of Wisconsin, La Crosse.