One-step pH shifting for simultaneous protein extraction and bioactive encapsulation from oilseed meals

Oilseed meals are underutilized due to limited protein functionality and low added value. This study developed a one-step aqueous pH-shifting strategy for simultaneous protein extraction and Ginkgo biloba leaf extract (GLE) incorporation. Defatted soybean and peanut meals were treated with GLE at 5, 10, 15, and 20 g, followed by alkaline extraction (pH 9.0) and isoelectric precipitation (pH 4.5). GLE incorporation increased ABTS and DPPH radical-scavenging activities by up to 45.87% and 28.19%, respectively. Soybean protein extraction yield increased from 34.2% to 38.5% at 5 g GLE, whereas peanut protein extraction yield decreased from 33.5% to 22.3%. Bioactives interacted with protein matrices mainly through hydrophobic interactions and hydrogen bonding, with moderate loading favoring compact structures and excessive loading inducing structural disorder. Soybean and peanut proteins showed distinct conformational responses to GLE incorporation. This aqueous pH-shifting approach without organic solvents enables the scalable upgrading of oilseed meals into functional ingredients.