Blueberry wine is a nutritional wine which aroma is affected severely by the fermenting condition. In this study, the influence of sulfur dioxide on the volatile composition and aroma of blueberry wine was comprehensively explored. The results indicated that in normal blueberry wine (NBW) fermented with sulfur dioxide, the titratable acid (TA) and total soluble solids content (TSSC) decreased slightly, whereas the ethanol, total phenolic, and vitamin C (Vc) contents increased significantly. The amount of volatile compounds declined significantly to 575 compared to 670 in traditional blueberry wine (TBW), and the relative concentrations of alcohols, acids, esters, and aldehydes markedly reduced. The relative odor activity value (ROAV) of 2,3-butanedione was the highest, and the number of the key aroma compounds shrunk obviously. The sweet, green, and fruity odors declined mainly ascribing to the reduction of 2-heptanol, acetic acid hexyl ester and 2-methyl-butanoic acid ethyl ester. The herbal, woody and floral odor mainly attributed to high contents of linalool, cyclohexene, 4-dimethyl-3-cyclohexene-1-ethanol, and ethyl nonanoate. These results indicated that sulfur dioxide retained some nutritional components, while it decreased the variety of the volatile compounds and affected the aroma of blueberry wine.

The purpose of this study was to comprehensively understand the formation mechanism of nutrient components and flavor compounds during the fermentation process of high-quality highland barley wine (HHBW). The dynamic changes of physicochemical properties, non-volatile compounds and volatile flavor compounds in HHBW at different fermentation times were investigated. The results indicated that the nutrient components and physiologically active substances in HHBW, such as proteins, β-glucan, total phenols and total flavonoids were higher than those in commercial highland barley wine (HBW). In addition, the analysis results of HS-SPME-GC-MS revealed significant differences in flavor compounds at each fermentation stage, with alcohol being the main flavor compound. The contents of aldehydes and ketones decreased rapidly with the progress of fermentation. Lactic acid was the most important organic acid in HHBW. Correlation analysis revealed a negative association between citric acid and most alcohols and esters, while tartaric acid and succinic acid exhibited positive correlations with alcohols. Bitter amino acids, such as valine, isoleucine, leucine, arginine and lysine, were positively correlated with most of the ester flavor compounds. The study can provide a reference for a deep understanding of the mechanism of the formation of the characteristic flavor of HHBW.

Highland barley alcoholic drink (HBD), as one of the most typical rice wines in Qinghai-Tibet plateau area, is generally brewed by adding Jiuqu to highland barley. However, the flavor and quality of HBD fermented with Jiuqu in various plateau regions are different. This study elucidated the potential correlation between the microbial community, physicochemical properties of five traditional plateau Jiuqu, namely Hongxin1 (HX1), Hongxin2 (HX2), Huairang (HR), Hoarfrost gypsophila (HG) and Tibet Qu (TQ), and volatile flavor compounds of HBD. Based on high-throughput sequencing (HTS) technology and LEfSe analysis, it was found that the bacteria and fungi of the five traditional plateau Jiuqu were quite different. Differential microorganisms were Weissella and Pichia in HX1, Lactococcus and Kazachstania in HR, Acetobacter and Rhizopus in TQ. Besides, HX1 and HX2 had higher esterification power, TQ had the highest fermentation power while HR had the lowest enzymatic properties. Finally, RDA and Pearson correlation analysis showed that esterification power and moisture content had positive effects on Lactobacillus, fermentation power and saccharification power were highly positively correlated with Pantoea and Rhizopus, but negatively correlated with Aspergillus. In flavor analysis, Rhizopus, Acetobacter were found positively correlated with alcohols and acids, which contributed to the formation of volatile flavor compounds, Lactobacillus_sanfranciscensis and Lactobacillus_sakei were positively correlated with phenolic compounds. This study showed that the flavor of HBD was seriously affected by the microbiota in Jiuqu, which could help to develop new fortified starter to improve the quality of HBD.

The traditional natural Jiuqu for brewing hulless barley wine contains a variety of complex microorganisms and enzymes. The uncertainty of microbial composition in Jiuqu and the existence of some miscellaneous microor-ganisms are not conducive to the production of high-quality hulless barley wine. In order to improve the flavor quality of hulless barley wine, the mixed starter was designed to reconstruct the fermentation microbial flora. Mold strains with high saccharification ability and yeast strains with good fermentation performance were screened from the traditional natural Jiuqu for brewing hulless barley wine and were identified. And then, mixed starters by molds and yeasts were used to ferment hulless barley wines on a laboratory scale. The physico-chemical indexes, sensory evaluation, volatile flavor compounds and electronic nose (E-nose) analysis of hulless barley wine brewed by different combinations of mold and yeast were analyzed. The hulless barley wine (W4 wine) brewed by the mixed starter Q4, which combined by Rhizopus oryzae, Saccharomyces cerevisiae and Wickerhamomyces anomalus, had the best volatile flavor and sensory score. This improvement was mainly re-flected in the higher content of esters (252.62 +/- 0.02 mg/L) and alcohols (72.77 +/- 2.03 mg/L), with esters accounting for 67.37 % of the volatile flavor compounds. In addition, the sensory score of "bitter" was the lowest in W4 wine while the scores of "sweet", "wine-aroma" and "fruit-aroma" were the highest. These results demonstrated that the mixed starter Q4 could effectively improve the flavor of hulless barley wine.

Previous studies have demonstrated that patients with type 2 diabetes mellitus (T2DM) often had the problems of fecal microbiota dysbiosis, and were usually accompanied with psychiatric comorbidities (such as depression and anxiety). Here, we conducted a randomized clinical study to analyze the changes in gut microbiota, serum metabolism and emotional mood of patients with T2DM after consumption of a high-fiber diet. The glucose homeostasis of participants with T2DM was improved by the high-fiber diet, and the serum metabolome, systemic inflammation and psychiatric comorbidities were also altered. The increased abundances of Lactobacillus, Bifidobacterium and Akkermansias revealed that the proportions of beneficial gut microbes were enriched by the high-fiber diet, while the abundances of Desulfovibrio, Klebsiella and other opportunistic pathogens were decreased. Therefore, the current study demonstrated that the intestinal microbiota alterations which were influenced by the high-fiber diet could improve the serum metabolism and emotional mood of patients with T2DM.

Ginkgo seed is a kind of food and medicine homologous goods. It is a feasible method to use Saccharomyces cerevisiae and Non-Saccharomyces yeast to ferment ginkgo rice wine (GRW) to remove the bitter taste and retain the biological activity. In order to better explore the formation of the unique flavor and taste of GRW, the volatile flavor compounds and sensory properties of GRWs fermented at different time were analyzed by GC-MS, GC-IMS and electronic sensory evaluation techniques. In addition, the changes of phenols in GRW were determined by LC-MS, and the antioxidant activity was dynamically monitored. GC-MS analysis showed the content of ethyl laurate, isoamyl acetate, ethyl heptanoate, 1-pentanol, ethanol and 1-propanol increased significantly with the progress of fermentation, among which ethyl acetate (OAV = 23.0), ethyl heptanoate (OAV = 44.4) and isoamyl acetate (OAV = 34.7) were the key flavor compounds of GRW at 60 h. GC-IMS analysis suggested some alcohols and ketones were significantly enriched at 60 h, including 2-pentanone, acetone, 1-butanol, 1-hexanol. Electronic sensory technology showed GRW at 60 h had strong mellow and fruity aroma due to benzoic acid, butyric acid and 2-methylbutyric acid. The bitterness and umami intensity in GRW gradually decreased, while the astringency and aftertaste increased. Furthermore, LC-MS results indicated the types of phenols increased, including quinic acid, shikimic acid, sorbic acid, etc., which significantly improved the antioxidant activity of GRW. Together, the flavor quality and biological activity of GRW had been effectively improved through microbial fermentation, which indicated that GRW had potential market prospects.