The Study On Impacts Of Delaying Harvest Time On ’Beiguo Lan’ Fruit Quality And Oenological Characteristics

Fruit and wine of Vitis amurensis Rupr. were riched in unsaturated fatty acids, trace elements, resveratrols and other polyphenols with antioxidant, anti-thrombotic, anti-cancer, anti-inflammatory and other pharmacological activity. However, fruit maturity was an important factor in impacting on fruit quality and wine quality. The establishment of optimal harvest time had great significance on brewing the best quality wines, which was used for breakthrough point in this paper. The berries of new cultivar of ‘Beiguo lan’ belonging to Vitis amurensis Rupr.(sampling at Sep. 11, 16, 21, 26 and Oct. 1, 6 and 11, 2014) were used as experimental materials, to make dry wine through the same process route. Meanwhile, the physicochemical properties and nutrients of these fruits and wines were detected, in order to determine the optimal harvest time and brew high quality wine. In addition, different Saccharomyces cerevisiae and SO2 concentration were designed to optimize the fermentation process of dry wine. The variation trends of physicochemical properties and nutrients in mash during the fermentation were monitored as well, to provide a theoretical basis for improving the fermentation process of dry red wine. The primary results were as follows:1. Through evaluating and testing the fruit quality and wine quality of ‘Bei guolan’ fruit harvested at seven different periods, the optimum harvest period of fruit was initially established. The results were: the appearance quality of fruit was excellent when fruit was harvested from Sep. 16 to Sep. 26, and the sensory quality of wine was excellent when fruit was harvested from Sep. 11 to Oct. 6. The fruits picked from Oct.1 to Oct. 6 had higher sugar and lower acidity, and the content of sugars in wine had no correlation with harvest time. However, the acidity of wine brewed by fruit harvested on Oct. 6 was the lowest, and it had significant difference with other harvest time. The content of total phenols, tannics, VC, anthocyanins, some mineral elements, amino acids and resveratrols in fruit and wine all increased before decreasing with the delaying of harvest time. The wine and fruits harvested from Sep. 26 to Oct. 6 had excellent nutritional quality, and the resveratrols content in fruit and wine harvested from Sep. 21 to Oct. 1 was higher than other harvest periods. To sum up, the optimal harvest time was from Sep. 26 to Oct. 6, namely 119~129 days after full bloom, for ‘Bei guolan’ in Jian city, during this time fruit quality and wine quality were excellent. It was significantly later than normal harvest time in Jian region(Sept. 15).2. The component of resveratrols and organic acids in fruit and wine were analyzed by high performance liquid chromatography. The results showed that the total amount of organic acids in fruit and wine gradually decreased with delaying harvest. Tartaric acid, malic acid, citric were main organic acids in fruit. However, tartaric acid, malic acid and lactic acid were determined as main organic acids in wine, and the tartaric acid content was higher than other organic acids in fruit and wine. The tartaric acid and malic acid content both decreased obviously in fruit and wine, and others content had no significant change. In fruit and wine, resveratrols were existed mainly with the form of trans-PD and trans-Res, and the content of cis-PD and cis-Res were extremely low.3. In the optimized experiment of fermentation process, eight kinds of commercially available yeasts such as CEC01, RV171, OFC, BV818, ADT, RV002, VF and OFD were used for fermentation. The results showed that the physicochemical indicators and nutrition qualities of wine fermented by yeast CEC01 were excellent, thus it can be used as high quality accharomyces cerevisiae. The experiment of SO2 concentration gradients showed that the integrated quality of wine were better with concentration of SO2(50~70mg·ml-1) in mash.4. The fruits harvested at different periods were fermented with the same process route. The results showed that the fermentation time of grapes harvested on Sep. 11, 21, 26 and Oct. 1, 6 was less four days than the fruits harvested on Sep. 16 and Oct. 11. The acidity of wine brewed by grapes picked at Oct. 6 and 11 was lower. The content of total phenols, tannins, anthocyanins of wine brewed by fruits harvested on Sep. 26, Oct. 1 and 6 were higher. All these indicators showed that the fruit harvested on Oct. 6 was more suitable for fermentation.5. Through detecting the physicochemical properties and nutrients of wort during fermentation, the content of total phenols, tannics, anthocyanins, amino acids, mineral elements and resveratrols in mash increased before decreasing and then remained stable. The content of total sugars and titratable acids quickly reduced firstly and then gradually stabilized, and the organic acids content slowly increased firstly and then quickly reduced. The content of tartaric acid and malic acid were significantly reduced, and the reduction of malic acid was higher than tartaric acid, meanwhile the lactic acid content increased significantly.