Fruit Quality Analysis and Comprehensive Evaluation of Different Varieties Walnuts and Pecan in Yunnan

To explore the quality evaluation indicators of walnut and pecan varieties cultured in Yunnan, the contents of 12 nutritional indicators which included in mineral elements, protein, crude fat, and vitamin C of 27 walnut varieties were determined. 12 indicators were comprehensively explored by correlation analysis, principal component analysis and cluster analysis to reveal variation and comprehensive quality of walnut resources in Yunnan Province. As indicated by the research findings: The variation of the content of 12 indicators was relatively rich, the variation coefficient ranged from 5% to 83%, among which the variation coefficient of vitamin C was the largest and the variation coefficient of crude fat was the smallest. The order of the average contents of 9 mineral elements was K>P>Mg>Ca>Mn>Na>Fe>Zn>Cu. The average contents of protein, fat and vitamin C were 15.62%, 68.63% and 4.66 mg/100 g, respectively. As demonstrated by the results of correlation analysis on 12 indicators, there was a significant positive correlation between protein and P, Fe, Mg, Ca, and Cu. The principal component analysis was used to comprehensively evaluate, showed that the comprehensive quality of walnut varieties 'Xiangcha', 'Yongping', 'Wanshu', and 'Xiaoyuanguo' were the best and the pecan variety 'Kaduo' was the better. The clustering analysis results showed that it can be divided into two major categories, namely the group rich in mineral elements and the group with high fat content. Subsequently, by combining with cluster analysis, K, Fe, Mg, Ca, Cu, protein and fat were determined as the critical indicators to evaluate the quality of walnut and pecan varieties cultured in Yunnan. Pecan varieties were suitable for extracting oil, and 22 main walnut varieties were suitable for direct consumption or the development of functional beverages rich in mineral elements and protein. The study clarified the critical indicators for evaluating the quality of Yunnan walnut and explored its quality characteristics, providing a scientific classification method, and laying a theoretical basis for the construction of the Yunnan walnut quality evaluation system.