Effects of wheat bran co-fermentation on the quality and bacterial community succession during radish fermentation

Co-fermentation of wheat bran, a nutrient-rich by-product, enhances the nutritional value of foods. The aim of this study was to investigate the effects of wheat bran on the physicochemical and organoleptic properties, and bacterial community succession of pickled radishes and related brines during a 56-day fermentation process. Scanning electron microscopy showed that the formation of a biofilm on the radish epidermis was promoted by wheat bran, along with a more reddish-yellow color, higher crispness, and better overall organoleptic properties at the maturation point (day 28). In addition, the co-fermentation of wheat bran promoted both ripening and aging, which meant it not only shortened the maturation period of fermented radishes, but also sped up the deterioration process. Analysis of 16S rRNA gene sequencing revealed that wheat bran addition stimulated the growth of Lactobacillus, leading to a higher titratable acid environment, which, in turn, suppressed the growth of potential pathogenic and spoilage bacteria (Rothia and Pseudomonas). Our results suggested a positive role of wheat bran on the quality and bacterial community of pickled radishes at the ripening stage. To better understand bacterial communities in fermented vegetables, epidermal and autochthonous microbiota should be monitored besides brine microbiota.