Chemical Optimization of Protein Extraction from Sweet Potato (<i>Ipomoea batatas</i>) Peel

Proteins isolated from sweet potatoes (Ipomoea batatas) have been shown to possess antidiabetic, antioxidant, and antiproliferative properties. The objective of this study was to chemically optimize a process for extracting proteins from sweet potato peel. The extraction procedure involved mixing peel with saline solvent to dissolve proteins and then precipitating with CaCl2. Quadratic and segmented models were used to determine the optimum NaCl concentration and peel to solvent ratio to maximize protein solubility while minimizing solvent usage. A segmented model was also used to optimize the concentration of CaCl2 used for precipitation. The highest yield was obtained by mixing blanched peelings with 59.7 mL of 0.025 mM NaCl per g peel and then precipitating with 6.8 mM CaCl2. The results of this study show that potentially valuable proteins can be extracted from peel generated during processing of sweet potatoes and industrial costs can be minimized by using these optimum conditions.