Effects of pre-treatment and drying methods on the pasting characteristics, amylose content and colour of Aerial Yam (Dioscorea bulbifera) flour
Rita Elsie Sanful, Ibok Oduro, William Otoo Ellis
The effects of various pre-treatments, solar and oven drying on the pasting characteristics, amylose content and colour of the aerial yam flours were evaluated. Flours were obtained from aerial yam (D. Bulbifera) by peeling, grating, steaming, and boiling, oven/solar drying, milling and sieving. The flours obtained were evaluated for their pasting characteristics, amylose content and colour. Between the two drying methods, the flour samples had pasting characteristics ranging from 51.55-94.80°C pasting temperature, 1.13 to 27.85 min pasting time, 6.50-57.00 peak viscosity, 0.50-46.00BU final viscosity, 6.50-57.00BU holding strength, -1.00-13.50BU breakdown and -18.00-3.00 BU setback viscosity. The yam flour samples had amylose and amylopectin contents ranging from 25.00-31.00 and 69.0-75.0 respectively. In all the pasting parameters measured, the oven dried samples obtained lower values in all the pre-treated samples except for the breakdown and setback viscosities. The high amylose content of the study sample indicates its potential for use in starch based products such as breakfast cereals. Overall pre-treatment did not improve lightness whiles steaming showed potential for inhibiting non-enzymatic browning. Oven drying showed increases in yellowness whiles solar drying increased redness indicating a high potential for non- enzymatic browning.