Characterization of the core microflora and nutrient composition in packaged pasteurized milk products during storage

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.

Effect of Storage Temperature on the Quality of Glass Bottled Pasteurized Whole Milk

Shelf life of pasteurized milk is relatively short, mainly due to cold chain conditions. This study investigated the effects of different storage temperatures （8, 10 and 12 ℃） on acidity, microorganism index, physical and chemical indicators and sensory quality of pasteurized milk packaged in glass bottle to determine the main factor affecting the quality of pasteurized milk during shelf life under different tem- peratures. The results showed that within the first five days, the protein, fat, lactose and non-fat milk solids contents in the milk samples did not change under different storage temperatures; the acidity was almost unchanged at 8 and 10 ℃, and in- creased slightly at 12 ℃; the sensory quality of milk samples did not change at 8 and 10 ℃, and began to decline from the 4th d at 12 ℃; the aerobic plate count in the milk samples accorded with the requirement of national standard at 8 and 10℃, and exceeded the national standard on the 5th day at 12℃. No coliform bac- teria were detected in the milk samples within the storage time at 8 ℃. When the milk samples were stored at 10 ℃, the coliform group count exceeded the national standard on the 5th day. When the milk samples were stored at 12 ℃, coliform bacteria began to be found in the milk samples from the 2rd day, and the coliform group count exceeded the national standard from the 3rd day. It indicated that stor- age time had a great impact on the quality of glass bottled pasteurized milk. Low storage temperature and relatively short storage time were conducive to the reten- tion of high quality of pasteurized milk. Coliform group count was one of the impor- tant factors affecting the quality of glass bottled pasteurized milk during shelf life.

Determination of antibiotic residues in the pasteurized milk produced in West Azerbaijan province,North West of Iran

Objective:To monitor antibiotic residues in pasteurized milk in West Azerbatjan province,North West of Iran.Methods:In this study,848 pasteurized milk samples were collected from factories and tested for the presence of antibiotic residues using the Copan test kit based on the manufacturer's instructions.Results:Results indicated that 30.14%of samples were contaminated with a variety of antibiotics based on the detection of associated residues and 3.19%of these samples were suspected.Given the current rise of antimicrobial resistance among microbial pathogens,these findings amplify the need to ensure continuous monitoring of pasteurized milk that intended for human consumption.Conclusions:Continuous monitoring of pasteurized milk may improve human health but also limit the development and transmission of antibiotic resistant strains in the environment.

Consumers’ Perception and Attitudes toward Packaged Milk in Turkey—A Descriptive Study

This study was conducted to analyze obtained data by consumer survey about packaged milk as long-life (UHT, ultra-high temperature) and pasteurized fluid milk (PFM). To achieve a 2.83% sampling tolerance, 1222 consumers were interviewed in person, and the data were collected. Although 76.4% of urban consumers (UCs) preferred UHT and PFM, the potential customer rate was 51.1% to 56.9%. In addition, the consumers who identify PFM with negative expression were identified as a high level of 68.4%. The definitions used for UHT can be considered as more neutral. 52.6% of consumers consider that there is a change in the composition of UHT and PFM during the production. The consumer groups (51.3%) thinking that this change is due to the addition of additives stand out. It is possible to assert that the main motivation factor for the negative attitudes of consumers towards UHT and PFM is the distrust of the technology in use.