The Research On Evaluation Of Fruit Quality Of The Thompson Seedless Grape

The parameters of the fruit appearance and the internal quality of the Thompson Seedless grapes fromthe main production areas and market in Urumqi were determined. The main production areas were Turpan,Toksun, Shanshan, and Hami. The differences of these parameters were systematically analyzed. The grapequality of samples from the main production areas was comprehensively evaluated and the evaluationindexes were selected by both the factor analysis and the R-factor cluster method, Variability anddistribution of the evaluation indexes were studied. The grading standard was discussed by probabilisticgrading method. The major results are as follows:1. There were significant differences in the fruit appearance and internal quality of the samples fromthe main production areas. This difference existed not only in Turpan, Shanshan, Toksun, and Hami, thefour production areas, but also in the different sampling sites of the same production area. The ear weightof grapes from Shanshan was significantly higher than the samples from the other three production areas,and the differences of the ear weight of samples in Turpan, Toksun, Shanshan and Hami were notsignificant (p>0.05). Both the pericarp weight and the ratio of pericarp to the fruit of Hami were higherthan the other three areas (p<0.05), while the differences of fruit weight, diameter of the vertical andtransverse, and the fruit shape index of Turpan and Hami were not significant (p>0.05). The L value andtotal acid of Hami and the a value of Turpan were significantly higher than the other three areas (p<0.05),the differences of b value, C value, hardness, total soluble solids, reducing sugar and total flavonoids ofHami and Shanshan were not significant (p>0.05), but the ratio of TSS to the acid, tannin and protopectinof these two regions was significantly different (p<0.05). The hue Angle h°, the tolerance of the tension ofthe fruit stalk, pH, vitamin C and soluble pectin among four areas were not significantly different (p>0.05).There were differences in the fruit appearance and the internal quality of different samples from the sameproduction area. The degree of difference was represented by a coefficient of variation. The variationcoefficient of ear weight, fruit weight, pericarp weight, the ratio of pericarp to fruit, a value, hardness, thetolerance of the tension of the fruit stalk, ratio of TSS to acid, vitamin C, tannin, the total of flavonoids,and the soluble pectin and protopectin were more than10%.2. In the period from July to September of2012, the quality parameters of appearance, texture andnutrition of the Thompson Seedless grapes were fluctuant. In the early stage of the grapes in the market,the ear weight and fruit weight were significant lower than that in the mid-and late stages. In contrast to theear weight and fruit weight, the change of the ratio of pericarp to the fruit of early stage was significanthigher than that in the mid-and late stages. The fruit shape index showed an overall trend of increasing andthen decreasing. The fruit shape index was smaller in the early and late stages, while the fruit shape indexare small where medium-term fluctuations where obvious. The hue angle h°showed different changes afterAugust14. Total soluble solids and reducing sugar content both showed an increased and then a decrease,and finally stabilized. The ratio of TSS to acid showed a rising trend of "fast-slow-fast". Total acid contentshowed a "slow-fast-slow downward trend. Vitamin C content overall showed a downward trend. Tannincontent generally showed a downward trend, and finally stabilized. The total content of flavonoidsgenerally showed a trend of "up-down-up-down-up-down". The tolerance of the tension of the fruit stalkvaried between235.2g~506.0g. The hardness of the fruit showed a "down-up-down" trend. The changes ofspringiness showed either an increase or a decrease. The adhesiveness of the fruit was fluctuant between -4.96to-37.07. The cohesiveness changed smoothly between July15to August23, increased significantlyafter August23, and decline slowly after August31. The resilience of fruit showed different changes wasbounded by August23. The chewiness of the fruit was fluctuat between1.19N to3.01N.3. The20indexes of147samples from the main production areas were compressed into9commonfactors by factor analysis. The model of factor score was constructed by factor score coefficient ofprincipal factors, and then a rotated variance contribution rate as weight to construct a comprehensiveevaluation forecast model of the Thompson Seedless Grape. The comprehensive score of147samples wascalculated by the model, and then sorted. The results showed that samples with excellent comprehensivecharacters were the2nd brigade Jiaohe village in Yar town, Pao town, the2nd brigade Sukexier village inLianmuqin town, and the5Squad4brigade Guoruo village in Yilahu town. After20indexes of grapesamples from the main production areas were analysised.9indexes which can represent the quality of theThompson Seedless grape were selected by the factor analysis, and the R-factor cluster method. The9evaluation indexes included hardness, total acid, tannin, total soluble solids, ear weight, fruit surface colorh°, fruit weight, fruit shape index, and the ratio of pericarp to fruit.4. The variation and distribution rule of9evaluation indexes of the Thompsons Seedless grape in themain production area were analyzed. The fruit indexes of the Thompson Seedless grape showed a largevariation. The coefficient of tannin contents was the largest (55.66%) and it was the smallest in fruit shapeindex(5.04%). According to the K-S normality test, There were some indexes which conformed to normaldistribution, including the fruit ear weight, fruit weight, the ratio of pericarp to fruit, fruit shape index, totalsoluble solids and total acid. However, the fruit surface color h°and tannin content conformed tochi-square distribution. Based on the distribution characteristics of each index, the classification pointswere determined by the probabilistic grading method. The value unified was divided into5grades. Thegrading standard for these indexes was recommended.