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. Pseudomonas, Streptococcus, and Acinetobacter 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 Pseudomonas increased in quality deteriorated milk (WY) and showed a significant positive correlation with heat-resistant protease content. Acinetobacter in quality deteriorated milk (QY) also considerably contributed to the content of heat-resistant lipase, which resulted in spoilage deterioration of UHT milk.

Docosahexaenoic acid (DHA; 22n-6) possesses multiple biological functions, including antioxidant activity and ameliorating hypertriglyceridemia. However, the application of DHA has been limited due to poor aqueous solubility and susceptible to oxidation. Here, ovalbumin (O), myosin (M), 7S soy globulin (S), and β-lactoglobulin (β), hydrolyzed by chymotrypsin, self-assembled into micelles, respectively. Adding incremental DHA to micelles caused endogenous fluorescence quenching of O, M, S, and β micelles, implying successful incorporation of DHA into hydrophobic cores of micelles (O (DHA), M (DHA), S (DHA), and β (DHA)). The results showed that micelles provided spatial stability and improved solubility, and stability against thermal and ultraviolet (UV) light for DHA. The uptake of DHA from M (DHA), β (DHA), O (DHA), and S (DHA) was 3.27-, 3.91-, 2.7-, and 3.95-fold higher, respectively, than that of DHA by Caco-2 cells. Encapsulation in micelles increased DHA aqueous solubility and uptake, which enhanced cellular endogenous antioxidant defense. Meanwhile, increased uptake of DHA was verified by HepG2 cells, and O, M, S, and β micelles were proven to increase DHA uptake to reduce lipid deposition. Our findings strongly support the possibility that O, M, S, and β micelles can be regarded as a carrier for loading DHA.

Pasteurized milk contains complex microbial communities affected by sterilization and storage conditions. This complex microflora may be the possible reason that pasteurized dairy products are highly prone to spoilage. In this study, packaged pasteurized milk products collected from dairy processing factories in China were stored at 0, 4, 10, 15, and 25 ℃ for 0−15 days and subjected to microbial identification using high-throughput sequencing. Accordingly, 6 phyla and 44 genera were identified as the dominant microbiota. Moreover, the changes in nutritional composition of the pasteurized milk, including in 16 free amino acids, 7 taste values, and 8 chemical constituents, were analyzed using principal component and multi-factor analyses. The Pearson correlation analysis identified Pseudomonas, Aeromonas, Paenibacillus, and Serratia genera as the core functional microbiota that significantly affects the nutritional composition of pasteurized milk. Hence, the results provide a comprehensive understanding of the safety and shelf-life of stored pasteurized milk.