Solid-state bioconversion of phenolics from cranberry pomace and role of Lentinus edodes beta-glucosidase

Cranberry pomace contains large amounts of phenolic glycosides, which are i mportant sources of free phenolics that have many food uses such as antioxi dants, flavorings, and nutraceuticals. Our hypothesis was that these glycos ides in cranberry pomace could be hydrolyzed by beta-glucosidase produced b y Lentinus edodes during solid-state fermentation On the basis of this hypo thesis, our objective was to investigate the potential of using cranberry p omace as a substrate for the production of free phenolics and beta-glucosid ase through solid-state fermentation by a food-grade fungus L. edodes. Our results suggested that L. edodes beta-glucosidase played a major role in re lease of phenolic aglycons from cranberry pomace during solid-state ferment ation. After 50 days of cultivation, the yield of total free phenolics reac hed the maximum of 0.5 mg per g of pomace, while the beta-glucosidase activ ity was about 9 units per g of pomace. The enzyme exhibited optimal activit y at 60 degrees C and at pH 3.5 and was stable at temperatures up to 50 deg rees C and between pH 3 and 6.5. The major free phenolics produced from cra nberry pomace were identified by HPLC as gallic acid, chlorogenic acid, p-h ydroxybenzoic acid, and p-coumaric acid. These results suggest that cranber ry pomace is a potential substrate for producing food-grade phenolics and f ungal beta-glucosidase. The L. edodes beta-glucosidase showed good stabilit y and tolerance to low pH and, therefore has potential applications in wine and juice processing for aroma and flavor enrichment through enzymatic hyd rolysis of glucoside precursors.