ABSTRACT
Roots and tuber crops include cassava, sweet potato, elephant foot yam, potato, aroids and other minor root crops such as African yam bean and East Indian arrowroot. Potatoes and yam contain a high amount of protein among other root crops. However, methionine and cystine limit amino acids in tuber crop protein. Sweet potato is a tropical tuber crop belonging to the family Convolvulaceae. The sweet potato plant is an herbaceous perennial vine having alternate round, triangular or cordate leaves and mid-sized sympetalous flowers. The colour of the flesh of the sweet potato varies from blue to purple and red. Anthocyanin pigments are purely herbal, soluble food colourants that impart red, purple or blue colour to plant or plant parts including fruits, roots and flowers. Sweet potato is a new world crop and is considered to originate from either the central or South American low–land. So far the oldest dried roots were discovered in the caves of Chilca Canyon of Peru.
