Characterization of pasteurized fluid milk shelf-life attributes

Pasteurized fluid milk samples were systematically collected from 3 commercial dairy plants. Samples were evaluated for microbial, chemical, and sensory attributes throughout shelf life. In general, product shelf lives were limited by multiplication of heat-resistant psychrotrophic organisms that caused undesirable flavors in milk. The predominant microorganisms identified were Gram-positive rods including Paenibacillus, Bacillus, and Microbacterium. Principal component analysis of sensory data collected using quantitative descriptive analysis showed that attributes related to milk flavor defects explained the largest amount of variance. These findings highlight the need to develop specific strategies for excluding bacterial contaminants from milk to further extend product shelf lives.