Modulation of walnut meal protein functionalities through low-temperature subcritical defatting: Insights into aggregation behavior and structural changes.

This study compared walnut meal protein (WMP) obtained from walnut meal defatted using low-temperature subcritical butane extraction (SBE-WMP) with that obtained from walnut meal produced by traditional high-temperature pressing (HP-WMP) to elucidate the effects of defatting methods on the structural and functional properties of WMP. Compared with HP-WMP, SBE-WMP exhibited a more ordered molecular conformation, with reduced oxidation and aggregation. These structural characteristics were accompanied by a smaller mean particle size (7.25 vs. 147.50 μm), higher solubility (66.93% vs. 51.88%) and a higher thermal denaturation temperature (105.58 vs. 95.96 °C). Additionally, SBE-WMP showed higher antioxidant activities (ABTS, DPPH, and hydroxyl-radical scavenging) than HP-WMP, with increases of 49.26%, 157.19%, and 35.33%, respectively. Conversely, the unfolding and aggregation observed in HP-WMP were associated with improved foaming and emulsifying properties. These findings highlight the distinct functional properties of WMPs and support their targeted applications.