Optimizing functional properties of perilla protein isolate using the response surface methodology

Abstract Response surface methodology (RSM) was used to optimize the ultrasound-assisted extraction parameters of perilla protein isolate (PPI), which has functional properties. A central composite experimental design was applied to investigate the effects of three factors (ultrasonic power, extraction time, and liquid-to-solid ratio) on six responses: protein yield, water solubility index (WSI), water absorption capacity (WAC), oil holding capacity (OHC), emulsifying activity (EA), and foaming ability (FA). Based on the RSM results, the optimum conditions were an ultrasonic power of 206 W, and extraction time of 32.4 min, and a liquid-to-solid ratio of 10.34:1. Under these conditions, PPI had high protein yield (26.1%) and functional properties (55.2% WSI, 3.6% WAC, 1.76 g/g OHC, 60.25 m2/g EA, 63.2% FA). Differential scanning calorimetry revealed that PPI was slightly denatured at 75.16 °C, and the amount of heat required to induce this denaturation was 0.03 J/g. SDS-PAGE presented protein bands that ranged from 14.4 to 66.2 kDa. Based on its functional properties, PPI can be used in the food industry.