Abstract: In our study, the quality changes of ‘Merlot’ and ‘Vidal’ icewines produced in Yili, Xinjiang Uygur Autonomous Region were monitored during two-year storage at intervals of one year. The physicochemical properties and aroma compounds of icewines were determined by high performance liquid chromatography (HPLC), titration, spectrophotometry and headspace solid phase microextraction combined gas chromatography (HS-SPME-GC-MS). According to the results of SPSS statistical analysis, good discrimination was achieved among icewines based on the physicochemical indexes. After two-year storage, the contents of total acid, volatile acids and malic acids in ‘Merlot’ icewine decreased by 5.9%, 13.2% and 39%, respectively, and lactate content increased by 57.2%. Browning index (BI), wine color (WC), color intensity (CI), color hue (CH), and the proportions of yellow (Ye) and red (Rd) changed significantly after one year of storage; CI, CH and Ye showed increasing trends with storage time, while Rd showed an opposite trend. After two-year storage, the contents of total acid and malic acid in ‘Vidal’ icewine increased by 9.8% and 33.1%, respectively, while the content of volatile acid decreased by 29.8%. WC, BI, CI, CH, and Ye changed significantly after one year of storage; WC and CI increased with storage time, whereas there was no significant difference in Rd or the proportion of blue (Bl). The results of principal component analysis (PCA) showed clear discrimination among icewine samples of different ages and between the two icewines. Two-year-old icewines contained the largest number of volatile compounds such as isopropyl alcohol, isoamyl acetate, ethyl hexanoate, hexyl acetate, decanal, citronellol, ethyl phenylacetate, phenethyl acetate, and β-damascenone in ‘Merlot’ icewine; and 1-pentanol, isoamyl alcohol, ethyl formate, isopropyl alcohol, furfural, 1-butanol, isoamyl acetate, acetaldol, hexyl acetate, octyl acetate, 3,4-dimethylbenzaldehyde, 5-hydroxymethylfurfural, phenethyl acetate, β-damascenone in ‘Vidal’ icewine. The above results showed that storage time had a significant impact the physicochemical properties and aroma compounds of icewines. Most importantly, we found that the volatile flavor composition of ‘Vidal’ icewine changed more significantly as compared to ‘Merlot’ icewine during storage.

Key words: icewine; storage period; physicochemical indexes; volatile compounds