Comprehensive Evaluation of Oil-use Traits of Walnut Varieties Based on Principal Component Analysis

To address the existing issue of ambiguous walnut varieties for oil processing, this study employed 26 main planted walnut varieties as the research object, completely analyzing their oil utilization features in order to filter out qualified walnut particular varieties for oil processing. By measuring seven phenotypic traits and nineteen physicochemical and nutritional quality traits of each variety, the coefficient of variation and correlation of each trait were calculated, and the traits closely related to oil quality were comprehensively evaluated using principal component analysis and cluster analysis. The findings revealed that there were relationships between walnut quality parameters. Among them, the kernel yield was found to be strongly inversely related to shell thickness (P<0.01), with the thicker the shell, the lower the kernel yield. There was a significant positive correlation between oleic acid and crude fat and stearic acid (P<0.05), linoleic acid was positively correlated with palmitic acid and stearic acid (P<0.01). Linolenic acid and δ-tocopherol were significantly positively correlated with γ-tocopherol (P<0.05) showed a significant negative correlation (P<0.05). The first principal component, according to the results of the principal component analysis, indicated the size of the walnuts and contributed the most to the variance. The second significant component denotes the oxidation stability of walnut oil. The third main factor was linked to oil yield. The fourth primary component dealt with the economic aspects of the nuts, while the fifth primary component might be used as an important predictor of walnut oil quality. The five key components explained 83.81% of the overall variation, showing that the majority of the information on walnut oil consumption features is available. Nut trichome, shell thickness, kernel weight, single fruit weight, kernel yield, moisture, crude fat, crude protein, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, total tocopherols, and total sterols were the representative indicators for evaluating the oil-use traits of walnut varieties. According to the comprehensive evaluation, the varieties with higher scores including Yunnan Huaning white shell, Xinjiang Wen 185, Beijing Liaoning 1, Yunnan Xixiang, Gansu Qingxiang, Hebei Xiangling, and others, indicating that the above varieties were more suitable for oil processing and could be used as a guideline for the selection of special varieties for walnut oil processing.