Effect of Hydrodynamic Cavitation and Drying Technique on Moisture Sorption Isotherm and Structural Properties of Egg White Protein Hydrolysate Powder

Protein hydrolysates have become key ingredients in food sector that govern both nutritional and functional behavior of food systems. However, the hydrolysate powders in general are hygroscopic in nature making them unstable. The powder properties may vary under different processing and drying conditions which can further influence the powder stability. Thus, the study explores the effect of hydrodynamic cavitation (HC) pretreatment and drying conditions on stability and microstructure of egg white protein hydrolysate (EWPH) powder for wider food application. The HC-pretreated EWPH powder obtained from two different drying methods, namely, freeze and vacuum drying, was assessed for their stability at elevated temperatures of 25, 35, 40, 45, and 55 °C for moisture sorption isotherm analysis. The sorption isotherms of EWPH were found to have a typical type III sigmoid curve, representing a hygroscopic material that fitted the GAB model well. The HC-treated EWPHs did not have much variation with temperature showing better stability. The density of vacuum-dried samples was higher by ~ 50% compared to freeze-dried samples. From DSC, it was confirmed that HC aided in improving the stability of freeze-dried EWPH powder where the highest denaturation temperature was found as 106.2 °C. Overall, a lower temperature of 25 °C and a relative humidity of 40% were found suitable for maintaining the stability of EWPH powder. Moreover, the study demonstrated that a pretreatment like HC had profound effect in enhancing the stability of protein hydrolysate powder, especially after freeze drying.