Effect of Various Processing Methods on the Pasting and Functional Properties of Aerial Yam (Dioscorea bulbifera) Flour

Aims: To determine the effects of various processing methods on the pasting and functional properties of Aerial yam (Dioscorea bulbifera) flour.
Place and Duration: Department of Food Science and Technology, Michael Okpara University of Agriculture, Umudike, between June 2012 and November 2012.
Methodology: Red and green cultivars of Dioscorea bulbifera were given tree treatments: boiling (1:10 w/v for 30 mins), roasting, soaking in 0.2% sodium Meta bisulphite (1:10 w/v for 7 hours), and untreated sample (control). Each of the samples was processed into flour. Pasting and functional properties of the flour samples were determined using standard methods.
Results: Boiling, roasting and soaking significantly (p ≤ 0.05) affected the pasting properties of the flour samples. Roasting, boiling and soaking significantly decreased (p ≤ 0.05) final viscosity (319 to 126 g) and (331 to 145 g), Trough (225 to 70) and (239 to 67), Peak time (5.66 to 4.88) and (5.58 to 4.96), Peak viscosity (267.75 to 119.67) and (278.17 to 108.58) for green and red cultivar respectively. Roasting significantly (p ≤ 0.05) decreased the breakdown values of both cultivars while boiling significantly increased the breakdown values of the two cultivars. The various treatments significantly (p ≤ 0.05) decreased the amylose content and increased the amylopectin values. There was no significant difference (p ≤ 0.05) in the in the bulk density of the samples. The roasted red cultivar had the highest gelatinization temperature (80°C) and significantly (p≤ 0.05) differed from the rest of the samples. Oil absorption Capacity (p ≤ 0.05) increased from 2.20 to 2.80 g and 2.30 to 2.80 g in green and red cultivars respectively.
Conclusion: Boiling, soaking and roasting affected the amylose and amylopectin ratio, pasting and functional properties of the flour samples. The functional and pasting properties of Dioscorea bulbifera studied showed that it can be used in both food and pharmaceutical industries.