Influence of Blanching and Drying Temperatures on Selected Properties of Sweet Potato (Ipomoea Batatas) Flour.

Abstract

Influence of blanching and drying temperatures on selected properties of sweet potato flour was investigated. Sweet potato samples were washed, peeled and sliced. They were then divided into five samples A, B, C, D and E. Samples A, B and C were treated by blanching at three different temperatures (55, 70 and 85oC) for 5 min and dried at temperatures of 55, 70 and 85oC. Sample D was sun dried slightly to reduce the moisture content while E was left in its fresh state. All the samples were milled and sieved. They were then analyzed for proximate and functional properties (water absorption, bulk density and swelling capacity). The study showed that both blanching and drying temperatures affected all the proximate properties of sweet potato except for crude fibre which was not significantly different (p<0.05) among treatments. Carbohydrate levels were generally higher for all the blanched samples compared to the untreated samples but values did not vary significantly among treatments. Moisture content of sweet potato flour, reduced with both drying and blanching temperatures, while protein content and fat increased with increase in blanching and drying temperatures. The effect of both parameters (blanching and drying temperatures) on the bulk density was also significant (p<0.05). The values of sweet potato flour samples varied significantly and positively from the untreated ones (fresh and sun dried). Thus, since the heat-treated samples had improved protein and carbohydrate contents and also better water absorption and swelling capacities, their flour have more desirable qualities.