Effect of varieties on physicochemical and pasting characteristics of water yam flours and starches

Abstract

Water yam (Dioscorea alata) flour and starch of ten varieties were processed using standard wet-milling procedure prior to the determination of their physico-chemical and pasting properties. The swelling power of the samples was characterized in the category of high restricted-swelling starch (9.21 to 11.03% for flours; 9.49 to 13.80% for starches). This characteristic is desirable for the manufacture of value-added products such as noodles and composite blends with cereals. The pasting temperature (78.05 to 86.13°C, for flours; 80.38 to 86.15°C for starches) and time (4.44 to 5.17 min for flours; 4.53 to 5.17 min for starches) of test varieties indicate higher gelatinization temperature and longer cooking time. Results of analyses of physico-chemical and pasting properties indicated significant differences (P < 0.05) among the varieties. All the varieties studied gave the potentials for the manufacture of these value-added products and non-food applications of starch such as in paper and textile industries. Moreover, the results obtained in this study also show that potential exists for selecting nutritionally superior varieties of D. alata (TDa 297 and TDa 00/00194 for flour, TDa 297 and TDa 98/01183 for starch) and these varieties could be good sources of diets to its consumers and serve as food security in developing countries.

Key words: Water yam, physico-chemical, pasting, flour, starch.