Commercially available and traditional dairy products differ in terms of their manufacturing processes. In this study, commercially available and traditionally fermented cheese, yogurt, and milk beverages were analyzed and compared. The metabolomic technique of ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF) in the MSE mode was used in combination with statistical methods, including univariate analysis and chemometric analysis, to determine the differences in metabolite profiles between commercially and traditionally fermented dairy products. The experimental results were analyzed statistically and showed that traditional and commercial dairy products were well differentiated in both positive and negative ion modes, with significant differences observed between the samples. After screening for metabolite differences, we detected differences between traditional milk beverages and yogurt and their commercial counterparts in terms of the levels of compounds such as l-lysine, l-methionine, l-citrulline, l-proline, l-serine, l-valine and l-homocysteine, and of short peptides such as Asp-Arg, Gly-Arg, His-Pro, Pro-Asn. The greatest difference between commercially available and traditional cheese was in the short peptide composition, as commercially available and traditional cheese is rich in short peptides.

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Traditional fermented dairy foods have been the major components of the Mongolian diet for millennia. In this study, we used propidium monoazide (PMA; binds to DNA of nonviable cells so that only viable cells are enumerated) and single-molecule real-time sequencing (SMRT) technology to investigate the total and viable bacterial compositions of 19 traditional fermented dairy foods, including koumiss from Inner Mongolia (KIM), koumiss from Mongolia (KM), and fermented cow milk from Mongolia (CM); sample groups treated with PMA were designated PKIM, PKM, and PCM. Full-length 16S rRNA sequencing identified 195 bacterial species in 121 genera and 13 phyla in PMA-treated and untreated samples. The PMA-treated and untreated samples differed significantly in their bacterial community composition and α-diversity values. The predominant species in KM, KIM, and CM were Lactobacillus helveticus, Streptococcus parauberis, and Lactobacillus delbrueckii, whereas the predominant species in PKM, PKIM, and PCM were Enterobacter xiangfangensis, Lactobacillus helveticus, and E. xiangfangensis, respectively. Weighted and unweighted principal coordinate analyses showed a clear clustering pattern with good separation and only minor overlapping. In addition, a pure culture method was performed to obtain lactic acid bacteria resources in dairy samples according to the results of SMRT sequencing. A total of 102 LAB strains were identified and Lb. helveticus (68.63%) was the most abundant, in agreement with SMRT sequencing results. Our results revealed that the bacterial communities of traditional dairy foods are complex and vary by type of fermented dairy product. The PMA treatment induced significant changes in bacterial community structure.

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BACKGROUND Previous studies have shown that Lactobacillus plantarum LIP‐1 (hereafter LIP‐1) has an obvious hypolipidemic effect, and microencapsulated probiotics can ensure the strains live through the gastrointestinal tract. Although there has been much research on both preparation and assessment methods for probiotics microcapsules, most assessments were made in vitro and few were validated in vivo. In this study, the protective effect of microencapsulation and the possible hypolipidemic mechanisms of probiotic LIP‐1 were evaluated in rats. Treatments included rats fed on a normal diet, a high‐fat diet, and a high‐fat diet with an intragastric supplement of either non‐microencapsulated LIP‐1 cells (NME LIP‐1) or microencapsulated LIP‐1 (ME LIP‐1). Lipid metabolism indicators were measured during the experiment and following euthanasia. RESULTS Microencapsulation increased survival and colonization of LIP‐1 in the colon. ME LIP‐1 was superior to NME LIP‐1 in reducing cholesterol. The mechanisms behind the hypolipidemic effect exerted by LIP‐1 are possibly due to promoting the excretion of cholesterol, improving antioxygenic potentials, enhancing recovery from the injury in the liver, cardiovascular intima and intestinal mucosa, promoting the generation of short‐chain fatty acids, and improving lipid metabolism. CONCLUSIONS This study confirms that microencapsulation provides effective protection of LIP‐1 in the digestive system and the role of LIP‐1 in the prevention and cure of hyperlipidaemia, providing theoretical support for probiotics to enter clinical applications. © 2019 Society of Chemical Industry

Traditional sour cream and butter are widely popular fermented dairy products in Russia for their flavor and nutrition, and contain rich microbial biodiversity, particularly in terms of lactic acid bacteria (LAB). However, few studies have described the microbial communities and metabolic character of traditional sour cream and butter. The objective of this study was to determine the bacterial microbiota and metabolic character of eight samples collected from herdsmen in Buryatia, Russia. Using single-molecule real-time (SMRT) sequencing techniques, we identified a total of 294 species and/or subspecies in 169 bacterial genera, belonging to 14 phyla. The dominant phylum was Firmicutes (81.47%) and the dominant genus was Lactococcus (59.28%). There were differences between the bacterial compositions of the sour cream and butter samples. The relative abundances of Lactococcus lactis, Lactococcus raffinolactis, and Acetobacter cibinongensis were significantly higher in sour cream than in butter, and the abundance of Streptococcus thermophilus was significantly lower in sour cream than in butter. Using a pure culture method, 48 strains were isolated and identified to represent seven genera and 15 species and/or subspecies. Among these isolates, Lactococccus lactis subsp. lactis (22.50%) was the dominant LAB species. Ultra-performance liquid chromatography–quadrupole–time of flight mass spectrometry at elevated energy was used in combination with statistical methods to detect metabolite differences between traditional sour cream and butter. A total of 27,822 metabolites were detected in all samples, and Lys-Lys, isohexanal, palmitic acid, Leu-Val, and 2′-deoxycytidine were the most dominant metabolites found in all samples. In addition, 27 significantly different metabolites were detected between the sour cream and butter samples, including short peptides, organic acids, and amino acids. Based on correlation analyses between the most prevalent bacterial species and the main metabolites in sour cream, we conclude that there may be a connection between the dominant LAB species and these metabolites. This study combined omics techniques to analyze the bacterial diversity and metabolic character of traditional sour cream and butter, and we hope that our findings will enrich species resource libraries and provide valuable resources for further research on dairy product flavor.

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