Physicochemical and digestive characteristics of high internal phase emulsion based on pumpkin seed oil bodies prepared at different pHs

In this study, we prepared high internal phase emulsions based on pumpkin seed oil body (HIPEs-PSOB) with 83% oil phase at pH 6.5, pH 9.0 and pH 11.0. The pH 11.0-HIPE-PSOB contained almost oleosin of 14.5 kDa, while other HIPEs-PSOB had oleosin and extrinsic proteins. With the increase of extraction pHs, the content of bound water, immobilized water, particle size, viscosity, viscoelastisity and shear stress decreased, and the free water and isoelectric point of HIPEs-PSOB increased. During stomach digestion, the hydrolysis rate of extrinsic proteins of all HIPEs-PSOB was higher than that of oleosin, and the proteins were hydrolyzed to produce resistant peptides. CLSM showed that all HIPEs-PSOB coalesced during gastric and the droplets were significantly reduced and dispersed in the intestine. The total FFA release decreased with the increase in extraction pH. This study provided a theoretical basis for the investigation and application of OBs and HIPEs. • Bound water and immobilized water of HIPEs-PSOB decreased with extraction pH 6.5–11.0. • Viscosity, viscoelastisity and shear stress of HIPEs-PSOB decreased with extraction pH 6.5–11.0. • Extrinsic proteins hydrolysis of HIPEs-PSOB was fast than oleosin in stomach phase. • Total FFA release of HIPEs-PSOB in intestinal phase decreased with increasing extraction pHs.