CHARACTERISATION OF MICROWAVED AND OVEN DRIED AERIAL YAM (Dioscorea bulbifera) STARCH

Abstract

Native Starch was extracted from Aerial yam (Dioscorea bulbifera). The starch extracted was dried using oven (at 300C for 24 hours) and microwaved for (30, 45, 60 seconds). Starch obtained using different drying methods and conditions were analysed for their physicochemical, functional properties and pasting characteristics. Results obtained showed that amylose, amylopectin, colour, pH, bulk density, swelling power, least gelation capacity, oil absorption capacity, water absorption capacity ranged from 26.87% to 32.77%, 66.89% to 73.12%, 40.35 to 53.65, 5.67 to 5.68, 0.568 to 0.704 g/cm 3, 7.26 to 8.43%, 9 to 15%, 112.89 to 121.98%, 164.39 to 306. 46% respectively. The pasting properties ranged from 48.9 to 80.70 C for pasting temperature, 10.9 to 20.50 minutes for pasting time, 493 to 545 BU for peak viscosity, 355 to 823 BU for final viscosity, 315 to 341 BU for breakdown viscosity, 178 to 217 BU for setback viscosity. The effect of different drying methods and conditions on the physico-chemical properties of the starch showed that oven dried starch has a relatively low bulk density compared to microwaved starch, and this implies that oven dried starch is better in terms of storability and transportation while higher bulk density of the microwaved starch showed that it will be a greater ease of dispersibility and reduction in paste thickness. The higher swelling power of the oven dried starch is a very important criteria for a good quality starch and water intake of the starch. The oven dried starch had better gelation capacity, because the lower the gel, the better the sample, and this is for starch granules to rise when incorporating into food products. The oven dried starch had higher water absorption capacity than the microwaved starch, in which it is suitable to entrap large amount of water during processing. The oven dried starch had higher advantages than microwaved dried aerial yam starch.