Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Nutrition, Dietetics, and Food Sciences

Committee Chair(s)

Donald J. McMahon


Donald J. McMahon


Craig J. Oberg


Jeffrey R. Broadbent


Randall K. Thunell


Cheesemaking is a process susceptible to defects caused by microbes not purposefully added by the manufacturer. While these bacteria are not a health concern, they can cause problems such as producing carbon dioxide inside the cheese. This can cause slits and cracks in cheese making cheese unsuitable for slicing. One such bacteria identified by cheese researchers at Utah State University and Weber State University is Paucilactobacillus wasatchensis. When present in cheese, it can cause gas formation by using galactose to supply its energy. In doing so, it takes this six-carbon sugar and converts it into a five-carbon sugar and at the same time releasing carbon dioxide.

The research team proposed a two-year project to develop a model system for studying this unwanted gas formation. This also involved investigation of other bacteria that could be added which use up these sugars and prevent Plb. wasatchensis from producing the unwanted gas. The BUILD Dairy program of the Western Dairy Center provided $85,000 for graduate student support and laboratory expenses for this project as a way to increase student investigations to solve problems faced by the dairy industry.

Information on the successful use of protective cultures to metabolize galactose before Lb. wasatchensis could use it to make carbon dioxide has been disseminated through presentations at regional and national microbiology, dairy, and cheese industry conferences.