Effect of Glycosidase Production by Rhodotorula mucilaginosa on the Release of Flavor Compounds in Fermented White Radish

Abstract

Fermented vegetables are highly valued by consumers for their distinct flavors and rich nutritional content. Microbial fermentation imparts distinct flavors to these vegetables, with red yeast being a common microorganism involved in the fermentation process. However, studies on the impact of red yeast on flavor development in fermented vegetables remain scarce. This study employed multi-omics to analyze the effect of glycosidase produced by Rhodotorula mucilaginosa on the release of bound flavor compounds in vegetables. The results indicate that the yeast possesses multiple glycosidase-encoding genes, with the activities of α-galactosidase, β-glucosidase, and α-mannosidase being detected. Following the inoculation of yeast into fermented vegetable juice, a significant increase was observed in the expression of the β-glucosidase gene (bglX) and the α-glucosidase maltase gene (malL), alongside an increase in the content of flavor compounds correlated with the enzymatic activity detected. The application of commercial glycosidase to vegetable juice resulted in increased levels of cis-2-pentenol, hyacinthin, geranylacetone, and 1-dodecanol, consistent with findings from yeast-fermented vegetable juice. Thus, Rhodotorula mucilaginosa can secrete glycosidases that hydrolyze and release endogenous bound flavor compounds in vegetables, thereby enhancing the flavor quality of the final product.