Enzymolysis kinetics and structural-functional properties of high-intensity ultrasound-assisted alkali pretreatment ovalbumin

Abstract

ABSTRACT This research investigated the enzymolysis kinetics of high-intensity ultrasound (HIU)-assisted alkali pretreatment Ovalbumin (OVA) through using Alcalase, and its structural and functional properties. The structural characteristics of OVA were performed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), surface hydrophobicity, Fourier Transform Infrared, and differential scanning calorimetry. SDS-PAGE analysis indicated that the pretreatment sample showed proportion of lower molecular mass components (14.3–20.1 kDa). There was an increase in the intensity of fluorescence spectrum and changes in functional groups after the pretreatment on OVA compared with the control (without treatment), which might be the reason for the significantly enhancing efficiency of the enzymatic hydrolysis. The thermal denaturation temperature of enzymatic hydrolysis of OVA after pretreatment was 95.1°C, which was 17.5°C higher than that of control. As compared to OVA (control), the enzymatic hydrolysis with HIU-assisted alkali pretreatment was found to significantly improve protein solubility, emulsifying properties, foaming ability (FA) and foam stability, oil, and water absorption capacity (WAC). Especially emulsifying activity index, FA, WAC, and oil absorption capacity were increased by 228.7%, 88.5%, 102.6%, and 67.4%, respectively (P< 0.05). A simplified kinetic equation for the enzymolysis model was deduced to successfully describe the enzymatic hydrolysis of pretreated OVA. The results proved the effects of the pretreatment on the substrate enhanced the enzymolysis process and this influence had relation to the structure changes. Furthermore, the enzymatic hydrolysis process for other proteins demonstrated the applicability of the model.