Project Number: 1935-41420-012-06
Project Type: Specific Cooperative Agreement

Start Date: Jul 21, 2003
End Date: Jul 20, 2008

Objective:
Pathogens such as Listeria monocytogenes pose an appreciable threat to the safety of our food supply. In recent years, this bacterium has been responsible for several large recalls and numerous illnesses linked to various foods, including cheese. In fact, a recent risk assessment by the USDA, FDA, and CDC on the "Relative Risk to Public Health from Food Borne Listeria monocytogenes Among Selected Categories of Ready-to-Eat Foods" identified fresh soft cheese such as Queso Fresco as having the highest predicted relative risk for listeriosis on a per serving basis among 20 categories of food. As such, additional research is warranted to better detect/type and control this food borne pathogen at various steps in the process of preparing and storing Mexican-style cheese. To this end, the primary objective of this specific cooperative agreement is to conduct microbial sampling of various areas, surfaces, and products on a dairy farm, within an integrated cheese processing plant, and in distribution/storage of Queso Fresco and Panela cheese in Mexico to monitor the efficacy of operations with the ultimate goal of pathogen reduction.

Approach:
Conduct microbiological and limited chemical analyses of samples from animals, equipment, products etc. on a dairy farm(s) that supplies milk for manufacturing Queso Fresco or Panela, as well as plants that manufacture such cheese. Information on the nature and niches of both the native flora and on L. monocytogenes will be useful for validating the public health threat and for developing interventions for lessening it in such cheese. Perform microbial profiling of the indigenous flora of the target cheese as it pertains to quality and safety attributes. Develop interventions that enhance the safety of such products without sacrificing quality. Perform sensory and textural analyses of Queso Fresco and Panela cheese made with raw milk in Mexico to develop cheese of equal quality made with pasteurized milk in the USA. Use these data to construct process risk models and to fill data voids in ongoing risk assessments.