Research on the quality deterioration of UHT milk products during shelf life: core microorganisms and related characteristics
Ruixue Ding, Kairu He, Rina Wu, Mengxue Lou, Zhili Liu, Yuqiong Piao, Xiaoyan Liu, Zhishen Mu, Junrui Wu
Abstract
Commercial sterility does not guarantee the sustained stability of ultrahigh temperature (UHT) milk over six months shelf life. We explore the microbiota presented in normal (SZ) and quality deteriorated UHT milk (QY and WY) products from the same brand. Based on high-throughput sequencing research results, 11 phyla and 54 genera were identified as dominant microbiota. <em>Pseudomonas, Streptococcus, </em>and <em>Acinetobacter </em>as core functional microbiota significantly influenced the UHT milk quality properties. Moreover, principal component analysis (PCA) and multivariate analyses were used to examine the quality characteristics, including 11 physicochemical parameters, 10 fatty acids, and 2 enzyme contents, in normal and quality deteriorated UHT milk. We found that the abundance of <em>Pseudomonas</em> increased in quality deteriorated milk (WY) and showed a significant positive correlation with heat-resistant protease content. <em>Acinetobacter</em> in quality deteriorated milk (QY) also considerably contributed to the content of heat-resistant lipase, which resulted in spoilage deterioration of UHT milk.