Insight into simultaneous destabilization of oleosomes during aqueous enzymatic extraction of Idesia polycarpa fruit oil by short-chain alcohol with talc.

Oleosomes as natural oil droplets are prone to severe emulsification in aqueous enzymatic extraction (AEE) of I. polycarpa fruit oil, limiting the recovery of free oil. This study aimed to investigate simultaneous destabilization and potential mechanism of short-chain alcohol (ethanol, EA; isopropanol, IPA) with talc on the oleosomes. EA, IPA, and their combination with talc improved the extraction of free oil, especially EA-Talc making the oil recovery rate up to that of IPA. The oleosomes were significantly destabilized, indicated by the decrease in absolute ζ-potential and rheological behaviors (apparent viscosity, G', and G″) as well as the increase in droplet size. Furthermore, oleosome instability was positively corrected with the reduction of protein, pectin, and phenolics contents at the interface. The presence of extrinsic and intrinsic proteins were lessened in the oleosomes; and native β-sheet of oleosome-related proteins were turned into α-helix, denatured β-sheet and β-turn, along with the exposure of tryptophan residues to aqueous phase. It was noted that IPA exhibited a better disruptive effect on the oleosomes than EA, and both of the alcohols exerted a combinedly action with talc. Therefore, the results demonstrated that EA, IPA, and their combination with talc had caused oleosome instability, and it was largely ascribed to the removal and structural unfolding of oleosome-related proteins. In view of food safety and regulatory acceptance, EA with talc might be used as an effective destabilizer of the oleosomes in the AEE of I. polycarpa oil.