Establishment and application of an evaluation model for table grape quality in cold region

Abstract To evaluate berry quality of table grapes, a total of 36 indicators of 38 table grapes cultivated in the plastic greenhouse of cold region were investigated in two consecutive years. There were 6 coreattributes, which covered appearence, texture, flavour and bioactivity factors, screened using with variability analysis, correlation analysis and principal component analysis (PCA). And a mathematical model, Y (composite score) = 0.070 × single berry weight + 0.048 × a* + 0.113 × chewiness + 0.169 × total soluble solids+0.366 × solid-acid ratio + 0.233 × total phenolics, was established by analytical hierarchy process (AHP). In the model, the total phenolics was variable based on the edible part, which was the content in skin of thin-skin grape or the sum content in skin and pulp of thick-skin grape. According to the model, the comprehensive score of each table grape was calculated with dimensionless process of original data. The berry quality of the 38 table grapes were divided into four grades, including Grade I (0.6 to 0.75, 10 cvs.), Grade Ⅱ (0.5-0.6, 11 cvs.), Grade Ⅲ (0.4-0.5, 10 cvs.) and Grade Ⅳ (0.1-04, 7 cvs.). Through the verification of regression analysis, the fitting degreebetween the model results and sensory assessment scores was up to 0.91, confirming that the mathematical model can provide a scientific reference for the berry quality evaluation of table grapes in cold region. The results of this study would supply the foundational data for further breeding and richness of table grape resource in cold region.