Moisture-Dependent Color Characteristics of Walnuts

TLDR: In this paper, the authors investigated the relationship between the color characteristics of the shell of walnuts and their moisture content, and the results indicated that the moisture content of the hulls with hulls at harvest was much higher than that of hulls without hulls.

Abstract: Characterizing the shell color of walnuts based on their moisture content at harvest can provide valuable information for performing walnut sorting before drying. The objective of this study was to investigate the relationship between the color characteristics of the shell of walnuts and their moisture content. Measurements were carried out for three walnut varieties, Tulare, Howard, and Chandler. The walnuts were sorted into two categories, namely with and without hulls at harvest. The Commission International de l'Esclairage's L*, a*, and b* color indices were measured to quantify the shell color after hull removal, and total color difference, hue angle (h*), and chroma (C*) values were calculated. The results indicated that the moisture content of walnuts with hulls at harvest was much higher than that of walnuts without hulls. The L* and ΔE values are highly correlated with moisture content and had different trends for walnuts with and without hulls. There was no clear relationship between other color...