Pasteurized milk is highly regarded for its ability to effectively retain nutrients and sensory quality, but its shelf life is limited by the heat-resistant microorganisms and their metabolic products remaining during the mild sterilization process. To solve this problem, the key is to identify the core residual flora and its metabolic network that lead to quality degradation. In this study, pasteurized milk stored at 4 ℃ for 0, 6, 9, and 12 days was examined to explore the changes in physicochemical properties, microbial communities, and functional metabolism during storage. Physicochemical analysis showed a slight decrease in fat, protein, and lactose content and a significant increase in acidity, particle size, and yellowness during storage. Among three pasteurization treatments (65 ℃/30 min, 75 ℃/15 s, and 85 ℃/15 s), the 75 ℃/15 s protocol optimally preserved nutrients and sensory quality, providing critical parameters for process optimization. Metagenomic analysis by Illumina HiSeq sequencing platform showed that Acinetobacter, Pseudomonas and Lactococcus might be the main core microflora leading to the deterioration of pasteurized products during storage. Pasteurized milk processed for 75 ℃/15 s can maintain good quality when stored at 4 ℃ for 0-9 days. Storing at 4℃ for 9 days may be the key storage point for microbial dynamics. Functionally, genes related to carbohydrate metabolism, amino acid metabolism, and energy metabolism increased with storage time. These metabolic pathways are crucial for microbial growth and may affect the nutritional composition and quality of pasteurized milk. Core microbiota primarily impacted milk quality through pyruvate metabolism and valine, leucine, and isoleucine biosynthesis pathways, leading to changes in acidity, bitterness, and texture. This study provides a basis for the monitoring and quality safety management of the main microorganisms and active metabolites during the production, processing and storage of pasteurized milk, and lays a foundation for obtaining high-quality pasteurized milk with long shelf life.

Proteins and plant polyphenols, important components in food systems, have been widely studied for their interactions, which are fundamental to the rational design of functional foods as well as to improving the bioavailability of polyphenols and proteins. In this review, we discuss the factors affecting the interactions between polyphenols and proteins. In addition, we summarize recent progress in research on the antioxidant, digestibility, allergenicity and antimicrobial activity of polyphenol-protein complexes and their applications in food and medicine. Moreover, we discuss directions for future research on polyphenol-protein complexes. It is hoped that this review will provide a theoretical reference for the rational and effective utilization of polyphenols and proteins andfor extending their application scopes.

As an extension of the previous research, this study aimed to comprehensively characterize the genome of Bacillus subtilis SNBS-3. Illumina second-generation sequencing technology and the third-generation high-throughput Pacbio sequencing platform were used for whole-genome sequencing of B. subtilis SNBS-3 isolated from traditional bean paste to obtain the key information of genome characteristics, gene function annotation and classification, phylogenetic evolution, and secondary metabolites. The results showed that the genome of SNBS-3 was a closed circular DNA of 4076387 bp in length containing 4000 protein-coding genes. A total of 3209, 2824, 2560, 147, 12 and 4 functional genes were annotated in the Clusters of Orthologous Groups (COG), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Carbohydrate-Active Enzymes (CAZyme), Comprehensive Antibiotic Resistance Database (CARD) and Virulence Factor Database (VFDB), respectively. Using the online software AntiSMASH and Bagel4, we found that it contained genes related to the synthesis of surfactin, mycosubtilin, plipastatin, bacilysin and bacillaene, as well as a complete gene cluster for the synthesis of the bacteriocin subtilosin A. Based on the results of antimicrobial test and proteinase K test, it was hypothesized that B. subtilis SNBS-3 had the ability to synthesize subtilosin A. In conclusion, the whole genome sequencing results of B. subtilis SNBS-3 show that it can produce a variety of bacteriostatic substances and thus have biocontrol potential. The results from this study provide a theoretical basis for further development and application of various bacteriostatic substances including the bacteriocin subtilosin A.

Pasteurization and ultra-high temperature treatment can kill most microorganisms in milk. However, since some bacteria such as Bacillus subtilis can resist pasteurization and ultra-high temperature treatments, even the most stringent heat treatments used to eliminate pathogenic microorganisms in the dairy industry cannot completely inactivate all microorganisms. In addition, highly heat-resistant spores can survive ultra-high temperature processing, so sterilized milk may be contaminated, causing bacterial spoilage in milk and dairy products during storage. In this review, the harms of Bacillus subtilis and its spores, spoilage-causing enzymes and biofilm to sterilized milk and the control measures for them are summarized so as to provide strategies for the prevention and control of Bacillus subtilis in sterilized milk and the quality assurance of milk and dairy products.

In order to further analyze the taste characteristics and processing stability of umami peptides from Tetragenococcus halophilus, 41 suspected umami peptides from T. halophilus were tested in this study, and three synthetic peptides (EEEEEE, HAAGMVE, and ESVYAST) with the highest umami values were selected using an electronic tongue. Their taste characteristics were analyzed by sensory evaluation, and the effects of temperature and pH on the stability of the umami peptides were analyzed. The results showed that all three peptides showed umami taste, with perceptual threshold ranging from 0.108 to 0.362 mmol/L. Among them, HAAGMVE demonstrated a particularly potent umami-enhancing effect. The stability analysis results showed that the umami values of EEEEEE, HAAGMVE and ESVYAST increased with increasing pH from 4.0 to 8.0, but remained stable in the temperature range of 25–100 ℃. EEEEEE exhibited the best stability. The results of this study provide a theoretical basis for the development and utilization of umami peptides derived from T. halophilus, and lay a foundation for improving the flavor quality of fermented products and promoting their industrial production.

Bacillus subtilis has a wide range of applications in the agriculture, industry, medicine and healthcare sectors due to its wide distribution and harmlessness to the environment. In recent years, Bacillus subtilis has been explored worldwide and applied as a new biological bacteriostatic agent, but the application of antibacterial substances secreted by it is still at a theoretical stage. This paper reviews the classification, mechanism of action, possible future applications and extraction optimization of antibacterial substances from Bacillus subtilis. The production of high-dose and high-purity bacteriostatic substances from Bacillus subtilis is an urgent problem to solved before the wide application of them in food preservation and sterilization technologies. This makes it necessary to find ways to improve the purity and yield of bacteriostatic substances. The review concludes with possible directions for future exploration of bacteriostatic substances.

Commercial sterility does not guarantee the sustained stability of ultrahigh temperature (UHT) milk over 6 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 activities, 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.

Ultrasonic-assisted thermal treatment, as a mild and effective emerging sterilization technology, has been successfully used to control the microbial safety of various foods. In particular, it has broad application prospects in the field of dairy processing. Ultrasonic provides a unique strategy to dynamically inactivate bacteria, which plays a significant positive role in alleviating the pressure on the dairy supply chain and reducing the economic loss caused by dairy spoilage. This article reviews the research progress that has been made in the past decade on the mechanism behind the ultrasonicassisted thermal sterilization of Bacillus subtilis in terms of the cavitation effect of ultrasonic, damage to the cell wall and membrane, generation of free radicals and antibacterial substances, and damage to cell metabolism-related enzymes. A new sterilization method for controlling the number of bacteria contaminating dairy products is proposed in this paper, aiming to provide a reference for better research and application of this technology for controlling the contamination of heat-resistant Bacillus during the storage and processing of dairy products, reducing the risk of dairy quality deterioration caused by the residue of heat-resistant Bacillus, and ensuring the quality and safety of dairy products during its shelf life.

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.