Comparison of different drying technologies for walnut (Juglans regia L.) pellicles: Changes from phenolic composition, antioxidant activity to potential application

Li Qingyang; Wang Ruohui; Sun Shiman; Shen Danyu; Mo Runhong; Liu Yihua

doi:10.1016/j.fochx.2023.101037

Comparison of different drying technologies for walnut (Juglans regia L.) pellicles: Changes from phenolic composition, antioxidant activity to potential application

Food Chem X. 2023 Nov 27:20:101037. doi: 10.1016/j.fochx.2023.101037. eCollection 2023 Dec 30.

Authors

Li Qingyang¹, Wang Ruohui¹, Sun Shiman¹, Shen Danyu¹, Mo Runhong¹, Liu Yihua¹

Affiliation

¹ Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China.

Abstract

The analysis of the phenolic profile in the walnut pellicle (WP) and its exploitability can help to promote the valorization of the industrial waste from walnut production. Three forms of 33 monomeric phenols in WPs were quantified based on our previously established LC-MS/MS method. The levels of protocatechuic acid and 4-hydroxybenzoic acid in the WPs were the highest, exceeding 400 μg/g. Antioxidant tests revealed that all three phenolic forms of WPs were effective antioxidants (IC₅₀: 2.12-35.05 µg/mL). The findings also revealed that drying temperature had a substantial type-dependent effect on phenolics and their antioxidant ability in WPs. KEGG enrichment analysis found that drying method has the greatest impact on WPs phenols in six metabolic pathways. Besides, 11 active substances in WPs were identified by a compound-targeted activity screening approach, indicating that WPs could be used as a natural antioxidant source in the development of medical and nutraceutical products.

Keywords: Active substances; Drying effect; KEGG; Phenolic; Utilization; Walnut pellicle.