(A Peer Review Journal)
e–ISSN: 2408–5162; p–ISSN: 2048–5170


Pages: 025-031
Bosede Adelola Orhevba and Veronica Abimaje

keywords: Sweet potato flour, blanching, functional properties, drying temperature


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.


Abidin PE 2004. Sweet potato breeding for northeastern Uganda: Farmer varieties, farmer-participatory selection, and stability of performance. PhD thesis Wageningen University, Wageningen, 152 pp. Ahmed M, Sorifa AM & Eun JB 2010. Effect of pre-treatments and drying temperatures on sweet potato flour. Int. J. Food Sci. Techn., 45: 726 – 732. AOAC 2005. Official Methods of Analysis of the Association of Analytical Chemists International (18th ed.). Gaithersburg, MD, USA. Chinda C, Teppei I & Toshitaka U 2018. Effects of hot-water blanching on the biological and physicochemical properties of sweet potato slices. Enginr. in Agric., Envt. and Food, 11(1): 19-24. Falade KO & Solademi OJ 2010. Modelling of air drying of fresh and blanched sweet potato slices. Int. J. Food Sci. and Techn., 45(2): 278-288. FAO 1990. Roots, Tubers, Plantains and Bananas in Human Nutrition. Rome: Food and Agriculture Organization. Geneflow 2009. https://www.bioversityinternational.org. Accessed on 25th July, 2017. International Life Sciences Institute (ILSI) 2008. Nutritionally improved sweet potato in assessment of foods and feeds. Comprehensive Reviews in Food Science and Food Safety, pp. 81-91. Jangchud K, Phimolsiripol Y & Haruthaithanasan V 2003. Physicochemical properties of sweet potato flour and starch as affected by blanching and processing. Starch/Starke, 55: 258-264. Katan MB & De Roos NM 2004. Promises and problems of functional foods. Critical Rev. Food Sci. Nutr., 44: 369–377. Narayana K & Narasinga-Rao MS 1984. Effect of partial proteolysis on the functional properties of winged bean flour. J. Food Sci., 49: 944-947. Polycarp O, Afoakwa EO, Budy AS & Otoo E 2012. Characterization of chemical composition and anti-nutritional factors in seven species within the Ghanaian yam (Dioscorea) germplasm. Int. Food Resources J., 19: 985-992. Sosulski FW, Garratt MD & Slinkard AE 1976. Functional properties of ten legume flours. Institute of Food Sci. and Techn. J., 9: 66 – 69. Ukpabi UJ & Ndumele U 1996. Evaluation of the quality of Garri produced in Imo State. Nigerian Food Journal, 8: 103-110. USDA 2009. US Department of Agriculture, Agricultural Research Service. National Nutrient Database for Standard Reference, Release 22. Nutrient Data Laboratory Home page. Van Hal M 2000. Quality of sweet potato flour during processing and storage. Food Rev. Int. 6:1-37. Woolfe J 1992. Sweet Potato: An Untapped Food Resources Cambridge University Press, Cambridge UK. Woolfe J & Jennifer A 1992. Sweet Potato: An Untapped Food Resource. Cambridge, UK: Cambridge University Press and the International Potato Center (CIP).