A review on the gastrointestinal protective effects of tropical fruit polyphenols.

Tropical fruits are popular because of their unique, delicious flavors and good nutritional value. Polyphenols are considered to be the main bioactive ingredients in tropical fruits, and these exert a series of beneficial effects on the human gastrointestinal tract that can enhance intestinal health and prevent intestinal diseases. Moreover, they are distinct from the polyphenols in fruits grown in other geographical zones. Thus, the comprehensive effects of polyphenols in tropical fruits on gut health warrant in-depth review. This article reviews, first, the biological characteristics of several representative tropical fruits, including mango, avocado, noni, cashew apple, passion fruit and lychee; second, the types and content of the main polyphenols in these tropical fruits; third, the effects of each of these fruit polyphenols on gastrointestinal health; and, fourth, the protective mechanism of polyphenols. Polyphenols and their metabolites play a crucial role in the regulation of the gut microbiota, increasing intestinal barrier function, reducing oxidative stress, inhibiting the secretion of inflammatory factors and regulating immune function. Thus, review highlights the value of tropical fruits, highlighting their significance for future research on their applications as functional foods that are oriented to gastrointestinal protection.

Diversity, enzyme production and antibacterial activity of Bacillus strains isolated from sesame-flavored liquor Daqu.

Daqu provides enzymes and precursors for liquor fermentation, and is the core of liquor fermentation. In this study, 11 Bacillus strains were isolated from sesame-flavored liquor Daqu, which can not only produce protease and amylase, but also have antagonistic effects on common pathogens Escherichia coli and Staphylococcus aureus. According to the gyrA gene phylogeny analysis, these 11 Bacillus strains belong to three species, B1, Y14, Y15, and YPDW9 belong to Bacillus mojavensis, W7, W13, YPDW6, and YPDW12 belong to Bacillus subtilis, and W14, Y5, and YPDW1 belong to Bacillus velezensis. According to the results of random amplified polymorphic DNA (RAPD) typing, there are three strains in Bacillus mojavensis, among which Y14 and Y15 are the same ones. All four Bacillus subtilis strains and three Bacillus velezensis strains are different. The specific primers were used to randomly amplify the biological control genes expressing lipopeptide antibiotics (bioA, bmyB, ituC, fenD, srfAA, srfAB, yngG,and yndJ), and the results showed that antagonistic genes other than fenD gene were amplified in four Bacillus mojavensis strains; Bacillus subtilis amplification was significantly different, but srfAA, bmyB and yndJ genes were all present; All genes were amplified in Bacillus velezensis except YPDW1 without ituC. This research provides new ideas for strengthening Daqu and lays a foundation for improving the quality of liquor.

Microbial composition and dynamic succession during the Daqu production process of Northern Jiang-flavored liquor in China.

The microbial community structure and succession regularity of six key periods during high-temperature Daqu production were revealed using high-throughput sequencing to explore the factors affecting the flavor formation of Northern Jiang-flavored Baijiu technology. The results showed that among the six Daqu samples, the bacteria mainly included Firmicutes, Actinobacteriota, and Proteobacteria, of which Proteobacteria was the most dominant. The primary fungus was Ascomycota. At the genus level, the primary bacterial groups were Lactobacillus, Weissella, Bacillus, Delftia, Achromobacter, Saccharopolyspora, Thermoactinomyces, Scopulibacillus, Pseudomonas, and Stenotrophomonas. The main fungal groups in the Daqu were Wickerhamomyces, Saccharomycopsis, Thermoascus, and Thermomyces. During the initial stage of Daqu production, the dominant bacteria were Lactobacillus (20.07%) and Weissella (48.30%). As the fermentation temperature of the Daqu increased, Achromobacter, Stenotrophomonas, and Delftia became the dominant bacteria during the first Daqu flipping period, the second Daqu flipping period, and the dry-fire period. During these three periods, many bacteria were eliminated, decreasing the bacterial diversity, while a decline in temperature was evident during the Daqu exit period. After adapting to the high-temperature environment, the accumulation of Saccharopolyspora (22.07%), Thermoactinomyces (16.73%), Scopulibacillus (27.13%), Kroppenstedtia (9.03%), and Bacillus (6.97%) increased the bacterial diversity during the Daqu exit period. Wickerhamomyces (83.47%) represented the main dominant fungus during the initial production stage but were eliminated with increased temperature. Furthermore, a higher temperature increased the abundance of Saccharomycopsis and Thermoascus, while Thermomyces gradually accumulated in the D, E, and F samples. Thermomyces (79.90%) and Thermoascus (13.83%) became the dominant fungi during the Daqu exit period. In this study, high-throughput sequencing technology was used to reveal the microbial diversity during the high-temperature Daqu production process of Northern Jiang-flavored Baijiu. This provided a scientific basis for improving the production process of this product in the future. Therefore, understanding the formation of the flavor substances and the related microorganisms in Northern Jiang-flavored Baijiu can provide guidance for using them to manipulate the preparation process while implementing microbial control and improving the production procedures. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02779-8.