A comparison of the fruit quality among five wine grape varieties introduced from Italy and two main cultivated varieties in China

【Abstract：Objective】In order to enrich wine grape germplasm resources, the Pomology Institute, Shanxi Academy of Agricultural Science introduced five wine grape varieties (‘Corvina'‘Corvinone'‘Garganega'‘Molinara'and‘Rondinella') from Italy in 2012. To further understand the features of the five wine grape varieties and provide reference for selection of wine grape varieties, we compared the quality traits of their matured berries with the main cultivated wine grape varieties (‘Cabernet Sauvignon 685'and‘Chardonnay 277') .【Methods】The experiments were carried out in 2015 and 2016.The berries were collected from grape vines grown in the vineyards of Pomology Institute, Shanxi Academy of Agricultural Science in Taigu, Shanxi province during September to October in 2015 and 2016.The samples were frozen using liquid nitrogen and stored in an ultra-low temperature freezer. The contents of phenolic compounds were analyzed for 2 years in Pomology Institute, Shanxi Academy of Agricultural Science in Taigu, Shanxi province according to the colorimetric method; while the aromaticcompounds were determined in the Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences in Beijing in 2016, using headspace solid phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) combined with automated mass spectral deconvolution and identification system (AMDIS) .【Results】The results showed that the mature berries of the seven grapes had an average weight between 1.4 g and 3.2 g, with oval or conical shape, and contents of the titratable acid and soluble solids ranged from 0.43% to 0.86% and 19.0% to 27.0%, respectively.‘Molinara'had the highest ratio of peel to pulp. Among the seven varieties, the juice yield of fruit was over 70% in all varieties except‘Chardonnay 277'. The phenolic contents in different parts of berries were significantly different. The total anthocyanin content in the four red wine grapes from Italy was significantly lower than in‘Cabernet Sauvignon 685', and the content in‘Molinara'was significantly lower than that in the other three red ones.‘Cabernet Sauvignon 685'had the highest contents of total phenol, tannin and proanthocyanidin in the peel, followed by‘Corvinone', which had the highest content of total flavonoids. The contents of tannins and proanthocyanidins in‘Garganega'were significantly lower and higher than in‘Chardonnay 277', respectively; the content of total flavonoids in‘Corvina'and‘Rondinella'were significantly lower than the one in‘Cabernet Sauvignon 685'.‘Chardonnay 277'had the highest content of phenolics in the pulp, followed by‘Corvina'and‘Corvinone', and those contents were significantly higher than‘Garganega'. Compared with‘Cabernet Sauvignon685', ‘Molinara'and‘Rondinella'had significantly higher tannin and lower proanthocyanidin contents, while the contents of total flavonoids were significantly and 92.9% higher and 19.0% lower, respectively. The seeds of‘Corvina'had the highest content of phenolics, which were significantly higher than that in‘Cabernet Sauvignon 685', whereas the seeds of‘Rondinella'had the lowest content of phenolics among the five red wine grapes. Compared with‘Cabernet Sauvignon 685', the content of phenolics in‘Corvinone'was significantly higher, while in‘Molinara', only the content of total phenolics was significantly higher. The content of phenolics in‘Garganega'seeds was significantly higher than that in‘Chardonnay 277'.‘Garganega'and‘Corvina'had the most and fewest species of volatile aroma components, respectively. Among the seven kinds of aroma compounds, medium-chain fatty acids were the most abundant, followed by alcohols, and acetates were the lowest. Except for‘Corvinone', the contents of medium-chain fatty acids in the rest of the five varieties were significantly lower than in‘Cabernet Sauvignon 685', while there was no significant difference in the contents among the five varieties.‘Cabernet Sauvignon 685'had the highest content of alcohols, following by‘Chardonnay 277', while the contents in the five Italian varieties were significantly lower than in them, and among the five Italian varieties, ‘Corvinone'was the highest while‘Corvina'the lowest. There were six to eight kinds of aroma compounds that exceeded their corresponding threshold, especially the five kinds that werecommon in all varieties, including decanal, phenylacetaldehyde, β-damascenone, β-ionone, and geraniol. Among them, phenylacetaldehyde, which yields the aroma of flowers, roses and honey, had the biggest odor activity value (OAV) ; β-damascenone generating the aroma of floral, lilac and stewed apple, had the second OAV in‘Corvinone'‘Molinara'‘Rondinella'and‘Chardonnay 277';while decanal showing the aroma of green and fresh, had the second OAV in‘Corvina'‘Garganega'and‘Cabernet Sauvignon 685'. Among all the aroma compounds exceeding threshold, the common one in‘Corvina'and‘Chardonnay 277'was 2-methoxy-3-isobutyl pyrazine, which shows the aroma of peppery and had the second OAV in‘Corvina'; while the common one in‘Corvinone'‘Cabernet Sauvignon 685'and‘Chardonnay 277'was isobutanol, showing the aroma of fusel, alcohol and green.TDN, which gives the aroma of kerosene, was the common aroma compound in‘Garganega'and‘Rondinella'; α-farnesene, which shows aroma of floral, was the common compound in‘Corvinone'‘Molinara'and‘Rondinella'; the unique aroma compound in‘Cabernet Sauvignon 685'was vitispirane B, which shows the aroma of camphor. The fragrance of flowers with the highest OAV was the most prominent aroma in the berries of the seven grapes, followed by caramel flavor (sweet fragrance) . The third fragrance in the berries of‘Corvina'‘Garganega'and‘Chardonnay 277'was vegetal flavor (mainly green pepper and raw green flavor) , while that in the other three varieties was fruit flavor.【Conclusion】The seven wine grapes had their own or common characteristics. The phenolics contents in different parts of berries were significantly different among the seven grapes. According to the characteristics of the phenolics and aroma, we can not only select the hybrids according to the target of breeding new varieties of wine grapes, but also improve the brewing according to the characteristics of different varieties.