Effects of walnut kernel pellicle on the composition and properties of enzymatic hydrolysates of walnut meal by peptidomics and bioinformatics.

The purpose of this article is to investigate the effects of walnut (Juglans regia L.) kernel pellicle on the composition and properties of enzymatic hydrolysis products of walnut meal using peptidomics and bioinformatics. In this study, a total of 3423 peptide sequences were identified in peeled walnut protein hydrolysates (PWPH) and unpeeled walnut protein hydrolysates (UWPH). Due to the presence of the walnut kernel pellicle, the enzyme cleavage sites of alkaline proteases on walnut precursor proteins were altered, resulting in differences in the number and length of the peptides obtained. Principal component analysis indicates significant differences between PWPH and UWPH. Combined with bioinformatics analysis, it was shown that walnut kernel peeling improved the release of peptides, formed more bioactive peptides, reduced allergenicity, and improved water solubility. Seven peptides with acetylcholinesterase (AChE) inhibitory activity were identified, and the peptide Val-Gly-Ala-Pro-Phe-Asp-Gly-Ala (VGAPFDGA) has the strongest inhibitory activity with an IC of 0.38 ± 0.01 mg/mL. These results confirmed that walnut kernel peeling could greatly change the composition of the walnut protein hydrolysates, and seven novel peptides were reported that showed significant AChE inhibitory activity.