Nutritional value of proteins in sweet potatoes of different colors

Ten randomly selected samples of sweet potatoes of different colors(i.e.,red,yellow and purple) were used for the evaluation.The amino acid composition and protein nutritional value of the sweet potatoes were evaluated by using the international standard methods.The results indicated that the total essential amino acids in all samples were higher than the FAO/WHO standards recommended for human nutrition,but lower than egg.All sweet potatoes were rich in Tyr,and had Met as their top limiting amino acid.The contents of protein and amino acids differed among the sweet potatoes of different flesh color,in the order of purpleredyellow.But the order was in reverse where the balance of the essential amino acids was concerned.