The Proximate and Functional Properties of African Yam Bean (Sphenostylis sternocarpa) Seeds as Affected by Processing
AbstractAfrican Yam Bean (Sphenostylis stenocarpa) known as AYB was subjected to different processing treatments such as soaking in water, blanching, cooking and roasting. Soaking was carried out for 24 h. A portion was blanched in hot water at 100oC for 2 min, 4 min, 6 min and 8 min respectively while the last portion was roasted at 100oC for 35 min,
150oC for 30 min and 180oC for 25 min respectively. The samples were then dehulled, dried and milled into flour. The proximate composition and the functional properties were determined for each of the samples. The result showed that the protein content was highest in the control sample (soaked in water for 24 h), while it decreased to 18.82% after 8 min blanching. The decrease was also noticed for the cooked samples to 17.97% for 20 min cooking and 12.53% for 60 min cooking while the roasted samples decreased to 11.55% and 11.33% at the 100oC for 35 min and 180oC for 25 min. The various heat treatments increased the oil absorption capacity from 2.51% to 4.05%; water absorption capacity from 3.76% to 4.68%; swelling index from 4.00 cm to 9.60 cm; bulk density from 0.58 kg/m3 to 0.89 kg/m3. Also, there were decreases in the gelation from 30oC to 20oC; wettability from 9 sec to 1 sec; foam capacity from 29.0 cm3 to 23.3 cm3 and viscosity from 12.30 to 23.3 cp. As a result of these improvements in both the proximate and functional properties of the flour, it could be incorporated in various foods to improve their nutritional value.
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