Different influences of β-glucosidases on volatile compounds and anthocyanins of Cabernet Gernischt and possible reason

Abstract The effects of three β-glucosidases (BG1, BG2 from Trichosporon asahii , AS from Aspergillus Niger ) on the aroma profiles of Cabernet Gernischt (CG) were investigated, coupled with an exploration of the possible reasons for the different performances of β-glucosidases under the two different conditions (hydrolysis of grape glycoside extract and wine-making). The analysis of headspace solid-phase micro-extraction and gas chromatography–mass spectrometry revealed that volatile flavour compounds in the β-glucosidase-treated samples were significantly increased. Specially, the wines treated with β-glucosidase BG1 occupied the highest concentrations of 19 out of 23 volatile compounds that exhibited significant differences. The investigation of the effects of pH or glucose on β-glucosidases showed that low pH is the main factor that exerts a more critical and irreversible influence on the activities and structures of β-glucosidase proteins. The stronger resistances to pH and glucose provided β-glucosidase BG1 a better ability in hydrolysing aromatic precursors than other enzymes under winemaking conditions. With the HPLC analysis, eight anthocyanins were identified from CG wine. Among the three β-glucosidases, BG1 showed the lowest influence on the main anthocyanin glycosides. These results suggested that the β-glucosidase BG1 may have some potential values to complement wine quality during the winemaking process.