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A comprehensive investigation of the differences in flavor profiles among different strains of fermented brown milk (FBM) is important to guide the improvement of the flavor quality of FBM. Seven samples were analyzed by dynamic headspace extraction (DHS) and gas chromatography–olfactometry–mass spectrometry (GC–O–MS), and a total of 73 odor compounds were identified. Key odor compounds including 3-methyl-1-butanol, ethyl acetate, linalool, furfuryl alcohol, 2-pentylfuran, hexanal, and 1-octen-3-ol, were screened by multivariate statistical analysis to reveal the flavor differences of FBM from different strains. 3-Methyl-1-butanol and ethyl acetate were found to be the key odor compounds distinguishing FBM by strain K56 from other strains, and the fermentation strains were found to be the key factors affecting the flavor of FBM compared to the fermentation substrate and fermentation process. This study provided a relatively systematic investigation of the flavor of FBM and could be used to monitor changes in odor components and sensory characteristics for product quality control. [Display omitted] • The odorants were detected in FBM using DHS–GC–MS for the first time. • Fermentation strains are a key factor in FBM flavor differences. • The FBM obtained from the K56 strain has fruity and whisky aromas. [ABSTRACT FROM AUTHOR]

Odor is an important attribute of fermented dairy products and is an important factor in determining consumer acceptance. However, the odor characteristics of brown lactobacillus beverage (BLB) and the differences in odor among different types of these products have rarely been studied. Here, a comprehensive analysis of different types of BLB were performed by SPME–GC–O–MS and SPME–GC×GC–O–MS techniques based on untargeted metabolomics. Compared with SPME–GC–O–MS, SPME–GC×GC–O–MS identified 26 new odor compounds in BLB, indicating that this method is more suitable for odor characterization of BLB. A total of 149 odor compounds were identified from 13 BLBs, of which 40 were odor-active compounds. Ketones, alcohols, acids, aldehydes, and esters accounted for about 80% of the total odor compounds and constituted the basic odor profile of the BLB. In addition to identifying indicator flavor compounds such as furfuryl alcohol, octanoic acid, and β -myrcene, which are responsible for the differences in odor profiles between different BLBs, the reference content ranges in BLBs were precisely quantified. These findings will provide new insights into the species traceability and odor characterization of BLB samples. [Display omitted] • Twenty six new odor compounds were identified in BLB by SPME–GC×GC–O–MS. • SPME–GC×GC–O–MS was more suitable for odor characterization of BLB. • Indicative odorants in the BLB and their content ranges were given. [ABSTRACT FROM AUTHOR]

The aim of this study was to select probiotic strains that could be used in drinkable yogurt to yield viable cells following storage at room temperature (RT). The uniquely high altitude conditions in Tibet and the alcoholic environment of certain products, such as the highland barley wine homemade in Tibet, may induce unusual characteristics of microbial strains. A total of 27 lactic acid bacteria were isolated from homemade highland barley wines. One strain, Lactobacillus reuteri WHH1689, demonstrated no ability for lactose utilization, exhibited a high survival rate during storage at RT in drinkable yogurts, and produced very weak post-acidification. This strain showed great resistance to conditions simulating the gastrointestinal tract, including strong adherence to HT-29 cells and inhibitory activity against Escherichia coli, Shigella flexneri, Salmonella paratyphi β, and Staphylococcus aureus. A dextran sulfate sodium (DSS)–induced mouse model was used to evaluate the in vivo influence of Lb. reuteri WHH1689 on the intestinal flora and showed that strain WHH1689 increased viable counts of bifidobacteria in feces of mice. The probiotic strain selected in this study—with its high survival at RT and lack of serious post-acidification problems—may provide significant improvements for dairy industry products by extending the storage time of dairy products with living cells. [ABSTRACT FROM AUTHOR]