Enzymatic glucosylation of citrus flavonoids to enhance their bioactivity and taste as new food additives

Abstract

Cyclodextrin glucosyltransferase (CGTase) is commonly used to produce cyclodextrins but its utility in flavonoids modification is rarely found. In the present study, an enzymatic transformation of citrus flavonoids by applying CGTase as the catalyst was investigated to produce a number of novel polyglucosylated derivatives from monoglucoside metabolites of citrus flavonoid diglycosides. Under the optimized conditions, the yield of glucosylated products achieved 80%. The water solubility and water partition coefficient of citrus flavonoids before and after the structural modification were compared. The results revealed that the water solubility of the flavonoids modified by glucosylation was significantly increased while the oil-water partition coefficient was just slightly reduced. Moreover, after glucosylation, the products have good anti-inflammatory and antioxidant effects. Interestingly, the taste property (bitterness and sweetness) of the glucosylated products was ameliorated. An evaluation with a Taste-Sensing System showed that the taste of the glucosylated products was strongly correlated with the attached rhamnosyl group (bitter taste) and glucosyl group (sweet taste), indicating that the amelioration of taste of flavonoids could be mainly attributed to the addition of glycosyl groups. The present study demonstrated a novel molecular engineering approach for the enhancement of water solubility and amelioration of taste for some citrus flavonoids, which may have potential applications in the functional food industry.