Abstract: To investigate the effect of water-soluble β-glucans on the fruit quality of‘Italian Riesling’grape，aqueous solutions of β-glucans at different doses（0，300，400 and 500 mg ∙ L-1）were sprayed at 53 and 63 days after flowering. Grape berries were randomly collected at the 60，67，and 95 days after flowering respectively to investigate the dynamic changes in basic physicochemical parameters，glycosidase activities and volatile compounds during fruits ripening. Results showed that the application of exogenous water-soluble β-glucans improved the content of pH，soluble solids，total sugar，total polyphenols，total free amino acids and yeast assimilable nitrogen，especially in 400 mg ∙ L-1 water-soluble β-glucans treated mature grapes，and was 7.02%，18.99%，18.75%，8.55%，35.96% and 17.05% higher than those observed in the control sample. Meanwhile，β-glucans spraying on grapevines significantly increased the activity of β-D-glucosidase，disaccharidases，as well as the contents and types of volatile compounds in grape skins collected at different sampling periods（P < 0.05）. Compared to the control，the activity of β-D-glucosidase，the total activity of three disaccharidases and concentrations of aroma compounds in grapes that received 400 mg ∙ L-1 β-glucans increased by 38.01%，28.72% and 31.18%，respectively. Except for n-hexanal and 2-hexenal，the content of other marker differential volatile compounds showed a positive correlation with glycosidase activity. Additionally，grapes treated with 400 mg ∙ L-1 β-glucans presented an advantage of development of fruity，flowery and sweet flavour. Taken together，applying 400 mg ∙ L-1 water-soluble β-glucans to the whole vine canopy had positive effects on berry quality of Italian Riesling grape.

Key words: wine grape, water-soluble β-glucans, glycosidase, volatile compounds