Quality Parameters of Composite Membranes for Microencapsulation: Evaluation by Statistical Optimization

Optimization of formulations in the manufacture of membrane is necessary to obtain the optimum concentration of base materials and plasticizer. The research was aimed to determine the optimum composition of the blends and that of the plasticizers in the manufacture of soy-protein isolate and cassava starch based membrane intended for food micro-particles. Soy-protein isolate and cassava starch blends were prepared and mixed at different proportions (100: 0%; 90: 10%; 80: 20%; 70: 30%; 60:40%; 50: 50% and 0:100%). Glycerol and sorbitol plasticizer were also prepared and mixed at different proportions (100: 0%; 80: 20% and 60: 40%). The experiment was conducted using response surface (User-Defined) method on design expert (version 11.1.0) software package. The response values of the membrane such as solubility, water vapor permeability, elongation at break, and puncture strength were best fitted into quadratic model while that of the tensile stress was best fitted into linear model considering their values of predicted R2 and adjusted R2. The optimum formulation for the manufacture of the composite membrane is B4 (70% soy-protein isolate and 30% cassava starch) and P2 (80% glycerol and 20% sorbitol) with the desirability value of 0.039. These optimum formulations provide responses for the membrane parameters as membrane thickness of 0.24mm, vapor permeability of 16.06 g H2O mm m-2 day kPa, membrane solubility of 45.95%, tensile stress of 20.71 MPa, elongation at break of 13.65% and puncture strength of 2.37 kN.