Effect of freezing treatment of raw material on the quality of'Italian Riesling'wine
Using'Italian Riesling'grapes as experimental materials,the effects of freezing raw materials at-24℃for 24 h on the basic physicochemi-cal properties,phenolic substances,aroma components and sensory quality of dry white wine were determined by ultra-high performance liquid chro-matography(UPLC),gas chromatograph-mass spectrometer(GC-MS)and sensory evaluation.The results showed that the basic physicochemical properties of'Italian Riesling'dry white wine were significantly changed,the pH,the contents of total phenols,tannins and monomeric phenols in-creased significantly(P<0.05),which increased by 14.11%,49.20%and 58.74%,respectively.The total content of aroma components significantly in-creased by 40.55%(P<0.05),and the variety aroma components increased by 2.The contents of C13-norisoprenoids and C6-compounds increased signifi-cantly(P<0.05),increased by 2.46 mg/L and 0.59 mg/L,respectively.The contents of esters and fatty acids in fermentation aroma increased signifi-cantly(P<0.05),increased by 40.12%and 19.97%,respectively,but the species decreased by 4.The sensory evaluation score of the wine after freezing treatment(83)were higher than the wine without freezing treatment(77).In summary,freezing treatment at-24℃for 24 h could effectively improve the quality characteristics of'Italian Riesling'dry white wine,and provide new ideas for the optimization of dry white wine making process.