Relationship between total microbial numbers, volatile organic compound composition, and the sensory characteristics of whole fresh chilled pasteurized milk

Total microbial numbers (TMN*) is a widely used, yet broad indicator of the quality of fresh chilled pasteurized milk (FCPM). Changes in the sensory characteristics (trained panel, n = 9), volatile organic compounds (VOC) composition (proton transfer reaction mass spectrometry, PTR-MS), and TMN were assessed for FCPM stored at 4.5 °C ± 0.5 for up to 26 days (12 days past the stated shelf life). Significant differences (p ≤ 0.05) in its VOC composition (m/z 41, 43, 45, and 47) and the sensory characteristics (10 out of 17 attributes) occurred at various TMN levels over this time. However, owing to differences in the spoilage potential of the microorganisms present there was only a weak relationship between TMN, VOC composition, and the sensory characteristics, which indicates that both the nature of the microorganisms present as well as the numbers present play a critical role in determining the shelf-life of FCPM.