Work

Characterization of walnut proteins extracted from meals and cakes with different oil production methods

Year: 2026

Type: article

Abstract: This study investigated the effects of three industrial oil extraction methods (solvent extraction, cold pressing, and hot pressing) on the structural, physicochemical, techno-functional, and digestive properties of walnut meal or cake protein, as well as their regulatory effects on rat intestinal microbiota. The protein contents of raw materials were 57.50% for solvent-extracted walnut meal, 48.65% for cold-pressed walnut cake, and 37.45% for hot-pressed walnut cake. The purity of the extracted proteins was 88.02% (WP), 86.51% (CWP), and 70.21% (HWP), respectively. Hot pressing induced protein unfolding and improved solubility and emulsifying activity. The total amino acid contents of the three walnut protein samples ranged from 100 to 108 mg/g, and the hydrophilic amino acid contents of CWP and HWP were significantly higher than WP. In vitro digestibility of HWP was the highest (37.40%), followed by CWP (30.05%) and WP (27.83%). Moreover, differences in digestibility further mediated the regulatory effects of walnut proteins on intestinal microbiota in SD rats. This work clarified the relationships among oil extraction processing, protein structure, techno-functionalities, in vitro digestibility, and regulation of intestinal microbiota, which would facilitate the valorization and potential food application of proteins from walnut meal and cake.

Source: npj Science of Food

DOI: 10.1038/s41538-026-01101-1