Enzymatic Hydrolysis of Sunflower Protein Isolate Using Alcalase: Optimization by Response Surface Methodology

The aim of the study was to optimize the hydrolysis conditions for obtaining sunflower protein hydrolysate (SPH). The hydrolysate was evaluated for its degree of hydrolysis (DH) and functional properties, including water holding capacity (WHC), oil holding capacity (OHC), emulsion capacity (EC), emulsion stability (ES), foaming capacity (FC), and foaming stability (FS). Three independent variables viz., pH (7, 8, 9) (X₁), temperature (45°C, 50°C, 55°C) (X₂), and hydrolysis time (30, 60, 90 min.) (X₃) were examined. Each variable was studied at three levels, coded as −1, 0, and +1. Response Surface Methodology (RSM) using a Box–Behnken design was applied to evaluate the effects of these variables on the measured responses. The ideal conditions for hydrolysing sunflower protein isolate were determined as pH of 7.9, temperature of 54 °C, and a hydrolysis time of 81.0 minutes. The RSM-generated model predicted a DH of 4.32 %, WHC of 1.71 g/g, OHC of 1.70 g/g, EC of 44.43 %, ES of 36.27 %, FC of 121.29 % and FS of 97.02 %. The experimental results closely matched the expected values, confirming the validity of the model. When compared to unhydrolyzed protein, sunflower protein hydrolysates (SPH) showed increased OHC, FC and FS, while decreased WHC, ES and EC. The results suggest that the modified SPH protein could be utilized as ingredient to improve the functional properties of the food products.