Effects Of Fruit Thinning On Quality Index In Grape And Wines

The winemaking varieties of Cabernet Sauvignon which belong to Vitis.vinifera L.from vineyard in Penglai of Shandong were used for experimental materials.Experiment was design to studythe effects ofdifferent fruit-thinning on qualityofgrapeduring maturation process, several parameters were determined, including longitudinaland transverse diameter, berry weight, temperature and humidity in cluster, reducingsugar, soluble solid, titratable acid, pH, polyphenols, tannins, anthocyanin, et al. Afterthat, fully-matured grapes were made to dry red wine respectively, and effects ofdifferent fruit-thinning on qualityofwine were analyzed. We focus on discussions abouteffects and variation of different fruit-thinning in grape and wine on tannins,polyphenols and anthocyanins. The main results are as follows:1．In the onset of grape berry ripening, grape of berry-thinning has higher sizeand berry weight, but significant lower than others at ripening.2．Different fruit-thinning can significant increase temperature and reducedhumidity in cluster compare with control, but berry-thinning was more obviousespecially in the time of higher temperature.3．Reducing sugar of berry-thinning more than others, control has lowest contentand increase little in the onset of grape berry ripening. At last, we can see grape ofberry-thinning was more than cluster-thinning, up cluster-thinning（half and all）morethan below cluster-thinning（half and all）, no difference between50%fruit-thinningand25%fruit-thinning.4．Fruit-thinning has lower titratable acid than control, but not found differencebetween it.5．Grape of berry-thinning can matured earlier, not found difference betweenothers.6．Fruit-thinning can increase soluble solid. Compare with up cluster-thinning（half and all）, below cluster-thinning（half and all）is benefit for it accumulation.7．Fruit-thinning increase pH. There was no difference between others except50%berry-thinning and up cluster-thinning were higher.8．Polyphenols and tannins of berry-thinning were obvious higher than others,and control were lowest.9．The content of five basic monomers of anthocyanin and total anthocyaninswith fruit-thinning were more than control except25%berry-thinning. 10．In wine, berry-thinning can increase alcohol, as so as up cluster-thinning（halfand all）,no difference between others and control. Volatile acid of belowcluster-thinning（half and all） and25%berry-thinning more than others. pH of upcluster-thinning（half and all） was highest all the way, control was lowest.Fruit-thinning have no effects on the residul sugar and total acid. Content ofpolyphenols from high to low are berry-thinning（50%and25%），up cluster-thinning（half）,up cluster-thinning （all） and below cluster-thinning （half）,belowcluster-thinning（half） and control.Content of tannins from high to low areberry-thinning（50%），up（below）cluster-thinning（half）and berry-thinning（25%）,up（below）cluster-thinning（all）and control. Content of total anthocyanins from high tolow was as tannins. Content of basic monomers anthocyanin of berry-thinning washighest, up（below）cluster-thinning（half）and control was after,up（below）cluster-thinning（all）was lower. Content of malvidin-3-o-glucoside was more thanothers, cyanidin-3-o-glucoside was nearly not found, and most of acylate anthocyaninshas been investigated.