Physico-chemical Properties of Three Araceae Species of Cocoyam Flour and The Rheological Properties of Its Starch Paste

Abstract

This study was carried out to examine the proximate, functional, and nutritional properties of three species of cocoyam in order to enhance its production and utilization. The current study was aimed at investigating the proximate, mineral, anti-nutritional, functional composition of three species of cocoyam flour and also the rheological properties of their starch paste. The three species of cocoyam, Xanthosomas sagittifolium (white), Colocacia esculenta ( red) and Xanthosomas mafaffa (koko poso) were obtained from market in Akure, Ondo State. The samples were peeled, washed, sliced, sundried, ground into flour, sieved and kept for analysis. The proximate, nutritional, mineral, anti-nutritional, functional composition of three species of cocoyam flour and rheological properties of their starch were determined using standard analytical methods. The proximate composition of the three species, white, red and koko poso flour revealed protein contents, 3.87%, 2.39% and 2.44% respectively. There was significant difference (p > 0.05) in percentage crude protein, carbohydrate, fat, ash, moisture content, but no significant difference (p > 0.05) in the percentage crude fibre. The proximate composition also demonstrated that coco poso (Xanthosoma mafaffa) species was nutritionally superior to the other two species (white and red). The mineral elements were in the following order Ca>K>Na>P>Fe. The results of the mineral analyses showed that cocoyam contain reasonably amount of minerals. The result for functional composition showed a significant difference (p>0.05) in water and oil absorption capacity, foaming stability, emulsion stability, emulsion capacity and least gelation concentration except for foaming capacity in sample C which was not detected. Anti-nutritional composition results showed high phytate and saponin in the three species of cocoyam flour, while tannin, oxalate and alkaloid were relatively reduced in the three samples. The results of the rheological analysis of their starch paste, revealed that sample A, Xanthosoma sagittifolium has the lowest retrograding property and sample C (Xanthosomas mafaffa) has the highest. The results showed that cocoyam regardless of species is a good source of carbohydrate, and nutrients. This study also showed that cocoyam starch could be used for dough making