Effect of Roasting on Endogenous Functional Components and Antioxidant Activity of Walnuts with Shells
2025
Mengyang WANG | Hexin ZHANG | Mei LI | Huaide XU | Ting ZHANG | Wenge ZHAO | Hongjie LEI
Walnuts are rich in various functional components, and proper roasting can help change the composition and content of functional components. However, there are few studies on the effects of roasting on the endogenous functional components and antioxidant properties of walnuts. Therefore, this study used whole walnuts as raw materials to investigate the effects of different roasting conditions (100~140 ℃，15~120 min) on the intrinsic functional components, fatty acid content, acid value, peroxide value, and antioxidant capacity of walnuts, with the aim of providing theoretical references for walnut roasting processing. The results showed that roasting (140 ℃, 60 min) significantly increased the content of functional components such as plant sterols (1128.36~1209.61 mg/kg), tocopherols (436.88~499.89 mg/kg), polyphenols (27.34~44.17 mg GAE/kg), linoleic acid (63.26%~63.86%), and α-linolenic acid (9.54%~10.03%). Furthermore, the antioxidant activities based on DPPH, FRAP, ORAC methods were also improved. However, the content of squalene (5.72~5.46 mg/kg), oleic acid (18.01%~16.44%) and the scavenging capacity of ABTS+ free radicals were decreased. After roasting, the acid value and peroxide value of walnuts were within the specified range by the Codex Alimentarius Commission (CAC). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that moderate roasting (140 ℃, 60 min) improved the endogenous functional composition and antioxidant capacity of walnuts. The research results provide a theoretical basis for the industrial roasting process of walnuts.
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