| To provide reference for high quality breeding and deepen the development of functional products，the gray values of 13 walnut kernels from the Xinjiang region were measured, and cluster analysis was conducted using gray value as an indicator, resulting in the 13 walnut kernels being divided into two groups: light-colored walnut kernels and amber walnut kernels. The oil content and major chemical components (aroma compounds, fatty acids, tocopherols, total phenol and mineral elements) of the two groups of walnut kernel were measured. Using orthogonal partial least squares discriminant analysis (OPLS-DA) and Pearson′s method to conduct correlation analysis between walnut kernel color and chemical composition.The results showed that light-colored walnut kernels with gray values ranging from 93.13 to 99.88, and amber walnut kernels with gray values ranging from 60.72 to 68.66. There were no significant differences in oil content and aroma compounds between the two groups (p>0.05). The light group demonstrated significantly higher levels of eicosenoic acid, γ-tocopherol, total tocopherols, total phenol, P, Ca, Mn, Fe, Na and Ba compared to the amber group (p<0.05). In contrast, the amber group exhibited elevated concentrations of palmitic acid, linoleic acid, δ-tocopherol and Zn content. OPLS-DA results indicated that the contents of Ba, Ca and Mn had the highest variable importance in projection values (VIP) at 2.39, 2.21 and 2.07, respectively. Pearson′s method analysis indicated that the contents of linolenic acid, arachidic acid, stearic acid, saturated fatty acids, and Co content were significantly negatively correlated with the gray value of walnut kernels, while the contents of palmitoleic acid, K and Cu were significantly positively correlated with the gray value of walnut kernels.In summary, there is a certain correlation between the color of walnut kernels and their chemical composition, which can be used for predicting the quality of walnuts. |
