Assessment of three White Yam (Dioscorea Rotundata) varieties for possible development into Flour

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A study was conducted to assess three white yam (dioscorea rotundata) varieties for possible development into flour in the Ashanti Region of Ghana from February to May, 2012. Field survey was conducted in five market centers in the Kumasi metropolis including Asafo, Bantama, Central (Bode), Krofrom (Moro) and Abinchi and one producing area in the Tanoso district of the Techiman municipality. Interviews, together with semi-structured questionnaires, were used in data collection from retailers and producers who were randomly selected from each location. Fifty retailers from the market centers and twenty farmers from the yam producing area. Laboratory work was also conducted at the Department of Horticulture of the Faculty of Agriculture, Faculty of Renewable Natural Resources, KNUST, Kumasi and Food Research Institute of the Council for Scientific and Industrial Research, Accra. Yam was collected from the Moro market in the Kumasi metropolis of the Ashanti Region, cut into chips and dried. They were them milled into flour and used for the laboratory work. The survey revealed that females (%) engaged in trading of the yam while the males engage in the farming. Education was, however, a problem for both yam farmers and traders. There were a lot of yam varieties in the country but majority of the respondent’s interviewed preferred Pona because of its taste and size. Labreko was one second choice because it had a better taste compared to Pona while Dente was one third preferred choice. Three yam cultivars were dried under three drying methods namely Solar, Sun and Oven. This study investigated the proximate, functional and pasting and colour properties of yam flour samples. The foam capacity, foam stability, Bulk density, swelling power, water and oil absorption index, moisture, protein and carbohydrate was investigated. Drying methods and cultivars were found to have significant effect (P˂0.05) on the functional, colour, pasting and proximate properties of all the yam flour samples, There were significant differences (p<0.05) in the foam capacity (61.00 to 37.33)g/ml, foam stability (51.87 to 28.10)g/ml, Bulk density (0.85 to 0.81) g/ml, Swelling power (6.33 to 3.56)g/ml, Moisture (12.67 to 4.00)%, Protein (5.25 to 4.380%, Fat (1.32 to 0.50)%, Carbohydrate (84.80 to 74.19)% Peak viscosity (458.67 to 259.67) BU, Setback (119.00 to 10.33) BU, and Browning index (31.44 to 8.43)%. There were significant difference (P<0.05) in the Pasting properties as some are thicker than others and also some are lighter in colour than others. The study shows that the yam flour samples developed were significantly different (p<0.05) in terms of the proximate, functional, pasting and colour properties.
A thesis submitted to the School of Research and Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfillment of the requirement for the award of the degree of Master of Philosophy (M.Phil.) in Post Harvest Physiology,