41-4 |
New York State fluid milk product shelf-life extension through elimination of spoilage microorganisms |
H. I. FROMM and K. J. Boor. Dept. of Food Science, Cornell Univ., 414 Stocking Hall, Ithaca, NY 14853-7201 Currently, bacterial spoilage is the most limiting factor in extending the shelf-life of conventionally pasteurized high temperature-short time processed fluid milk products beyond 14 days. Development of undesirable sensory attributes throughout shelf-life is largely attributed to the growth of spoilage microorganisms. We hypothesize that the predominant microorganisms present in processed milk products predictably influence the flavor profile of the products. Observations from three commercial dairy plants will facilitate the development of appropriate strategies to eliminate spoilage microorganisms and allow shelf-life extension of processed fluid milk products in New York State. The overall objective was to develop and apply strategies to extend shelf-life of commercial fluid milk products in New York State. The approach taken to achieve this goal was to employ biotechnology-based methods to identify the predominant spoilage microflora found in pasteurized 2% fat fluid milk. Quantitative descriptive analysis was used to determine key sensory attributes associated with the presence of identified spoilage organisms throughout the duration of shelf-life. Identification of microbial isolates obtained from fluid milk samples at initial, 7, 14 and 17 days post-processing was completed using 16S rDNA sequencing. A trained panel consisting of 12 human subjects described the principal sensory characteristics of the fluid milk samples on the same days post-processing using a quantitative descriptive analysis (QDA) approach. Our results demonstrate the potential for extending processed fluid milk product shelf-life beyond 14 days post-processing, as shown by the 40% of samples (n=69 samples tested) that met the regulatory microbial standard of <20,000 CFU/ml for Grade A pasteurized milk at 17 days post-processing. Identification of dairy spoilage organisms has provided the necessary information to determine entry points in order to reduce or eliminate contamination reservoirs, enabling the production of fluid milk products with shelf-lives longer than 14 days in NYS dairy plants.
Session 41, Dairy Foods: Dairy microbiology
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