Physico-chemical properties of flours and starches from selected commercial tubers available in Australia

Physico-chemical properties of flours and starches extracted from the tubers, taro, yam, and sweet potato commercially available in Australia were investigated. Results pointed out that each of the different tubers might be utilized for specific applications in food processing. In contrast to the sweet potato and yam flours and starches, with larger particle size distributions from 28.3 and 251 μm, the taro flour with a mean particle distribution size from 1.067-64.19 μm is better suited in applications where improved binding and reduced breakability is required. Paste clarity of the sweet potato was above 30% light transmittance whereas the other two tubers (yam and taro) had less than 10% light transmittance in both cases. All flours and starches exhibited variable pasting behavior, with starches having a higher viscosity. Among flours, taro had the highest peak and final viscosity. Yam flour and starch were more stable against heat and mechanical treatment. The extracted mucilage from these tubers showed apparent shear thinning behavior. Concentration dependant flow behavior of all mucilage samples was successfully fitted by the Power Law (Ostwald), Hershel Buckley and Casson models.