Chemical and nutritional assessment of sweetpotato proteins

The solubility of sweetpotato nitrogen increased outside the pH range 3-6 for the pulp, and 2-5 for the peel of the two varieties namely, "Abees" and "Giza 69". The minimum nitrogen extractability occurred between the pH range 3-4, and 4-5 for the peel and pulp, respectively. The sweetpotato protein isolates were prepared separately from both peel and pulp of the two varieties. The former had the highest values of carbohydrates and ash while the latter had the highest values of protein and fat. The in-vitro digestibility of sweetpotato proteins and casein by pepsin-pancreatin was studied. Casein was more easily digested than the proteins of sweetpotatoes, whose digestibilities were higher in the pulp than in the peel of the two varieties. No trypsin inhibitor activity was detected in peel and pulp of both varieties under test. The effect of the variety of sweetpotatoes on the protein patterns was studied using the polyacrylamide gel electrophoresis and varietal specific patterns were obtained.