Physicochemical and rheological properties of peanut oil body following alkaline pH treatment

Abstract

Effects of alkaline pH treatment on composition, physicochemical and rheological properties, and microstructures of peanut oil body (OB) were investigated. Alkaline pH treatment could remove parts of proteins and phospholipids from OBs surface, and adsorbed proteins on OBs surface were almost completely removed at pH 11, yielding pure OBs. Essential amino acids and hydrophobic amino acids of OBs increased with the increase of alkaline pH. Although alkaline pH had no effect on fatty acid composition, it did have a significant effect on phospholipid composition. With the decrease of adsorbed proteins content, isoelectric point increased, and stability of OBs decreased, which is benefit for demulsification. pH and NaCl are important factors affecting stability of OBs by changing electrostatic repulsion, while effect of temperature on stability of OBs is small and irregular. OBs were stable system dominated by elasticity, and apparent viscosities of pH 8.0-OB, pH 9.5-OB, and pH 11.0-OB were obviously lower than crude-OB. It was also found that alkaline pH treatment had little effect on microstructures of peanut OBs. Results from this study suggest that improvement of OBs extraction technology to remove adsorbed proteins is important for demulsification.