Optimization of extraction process of hemp seed protein by reverse micelle method and study on its physicochemical properties and digestibility

ObjectiveThe process was optimized and the physicochemical properties of the obtained hemp seed protein, extracted by using reverse micelle method, were analyzed.MethodsThe key factors affecting the extraction rate of protein, such as Aerosol-OT (AOT) mass concentration, water addition, buffer pH, KCl solution concentration, solid-liquid ratio, extraction temperature and time of pre-extraction process, and pH, KCl concentration, extraction time and temperature of post-extraction progress, were analyzed by single factor analysis and response surface optimization. The solubility, water holding capacity, oil holding capacity and digestion characteristics of the obtained protein were investigated.ResultsThe optimal process conditions for the reverse micelle pre-extraction were obtained as follows: AOT mass concentration 0.090 4 g/mL, buffer pH 6.54, water addition 0.105 8 mL/mL, KCl concentration 0.05 mol/L, solid-liquid ratio 1∶30 （g/mL）, extraced for 60 min at 50 ℃. The pre-extraction rate was 71.38%. The optimal process conditions for the reverse micelle post-extraction were obtained as follows: pH 7.5, KCl concentration 1.5 mol/L, post-extraction time 45 min, temperature 27 ℃. The post-extraction rate was 80.59%, and the total extraction rate was 57.53%. The white and fluffy protein powder with purity of 98.12% was obtained by dialysis and freeze-drying. Its solubility changed significantly with pH values. The water holding capacity was 0.71 g/g, the oil holding capacity was 3.57 g/g, and the digestibility was 93.83%.ConclusionReverse micelle method can be used to extract hemp seed protein. The characteristics of excellent oil holding capacity and high digestibility make hemp seed protein have unique advantages in food application.