| Most aroma compounds are present as glycosidic aroma precursors in grapes, and theβ-glycosidase is considered as the key enzyme of the hydrolysis to release free aroma compounds. So it is essential to investigate the glycosidic aroma precursors and β-glycosidase in grapes for the improvement of wine aroma. To find the differences of β-glucosidase activity and concentation of glycosidic aroma precursors among different grape varieties, to explore the changes of β-glycosidase activity and potential aroma during grape ripening, to reveal the relationship among β-glycosidase activity, concentration of glycosidic aroma precursors and maturity indices, in this work, using grapes with different maturity and different variety grapes as study objects, their β-glucosidase activity, concentation of glycosidic aroma precursors and maturity indices were analyzed. And the β-glucosidase activity of grapes was measured using colorimetric method with p-nitrophenyl-β-D-glucopyranoside(p NPG) as substrate, and concentration of glycosidic aroma precursors in grape berries with different maturity was determined through quantification of glycosyl glucose(G-G).(1) There are differences among β-glucosidase activity in different varieties of grapes.Using Muscat, Meili, Cabernet Gernischt, Vitis amurensis Rupr, Muscat Blanc, Ecology grapes as study objects, the differences of β-glucosidase activity and concentation of glycosidic aroma precursors among different grape varieties were analyzed in this work. The results show that the β-glucosidase activities of Must varieties including Muscat and Meili were lower, and were 8.05±0.32 U/g FW and 3.71±0.22 U/g FW, respectively. Andβ-glucosidase activity of Neutral varieties Ecology was highest, reached 20.13±2.16 U/g FW.Enzyme activity of non-muscat aromatic varieties Cabernet Gernischt was 15.35±0.32 U/g FW,and Enzyme activity of Vitis amurensis Rupr and Muscat Blanc grapes was 14.08±1.01U/g FW and 3.04±0.26 U/g FW, respectively.(3) The results showed the concentration of aroma glycosides in different varieties of grapes with a difference. The concentrations of glycosidic aroma precursors of Muscat, Meili,Cabernet Gernischt, Vitis amurensis Rupr, Muscat Blanc, Ecology grapes were analyzed.Concentrations of aroma glycosides in Cabernet Gernischt grapes and Vitis amurensis Rupr were highest and were 0.6386±0.1114 g/L and 0.5262±0.0801 g/L; respectively. Then followed by Meili, Ecology and Muscat Blanc, their contents were 0.2798±0.0496 g/L,0.2398±0.0378 g/L, 0.2302±0.0444 g/L; respectively. Concentration of aroma glycosides in Muscat grapes was the lowest and only 0.0819±0.0156 g/L(3) The β-glycosidase activity and concentation of aroma glycosides in grape berries increased with the maturity of grape berry. The β-glucosidase activity of Cabernet Sauvignon,Merlot, Pinot Noir grapes during maturity and the concentation of aroma glycosides of Cabernet Sauvignon and Muscat grapes with different maturiy was measured. And the results showed that the β-glycosidase activity and concentation of aroma glycosides tended to increase with grape ripening, and the rise scope became gentle near to the physiological maturity.(4) Correlation analysis and regression analysis of aroma glycosides, β-glycosidase activity and related chemical indices in Cabernet Sauvignon grapes during ripening was analysed. The results shows that the concentation of aroma glycosides in grapes during ripening was significant related with their β-glycosidase activity.(4) Correlation analysis and regression analysis of aroma glycosides, β-glycosidase activity and related chemical indices in Cabernet Sauvignon grapes during ripening was analysed. The results shows that the concentation of aroma glycosides in grapes during ripening was significant related with their β-glycosidase activity.KEY WORDS: Grape, Glycosidic aroma precursors, β-Glycosidase activity, Maturity indices... |
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