ABSTRACT

 Dioscorea bulbifera (aerial Yam) popularly called Adu by Igbo speaking people of Nigeria was evaluated. The effect of various processing methods (soaking, boiling, roasting) on the functional properties, pasting properties, and amylose/amylopectin ratio of two cultivars (Green and red) of Dioscorea bulbifera was evaluated. The functional properties evaluated were bulk density, swelling index, water absorption capacity, oil absorption capacity, wetability, gelatinization temperature. There was no significant difference in the bulk density values of the two varieties studied. However the roasted flour sample had the highest bulk density (0.52g/m/). Green roasted flour sample had the highest swelling index (3.02) and was significantly different from other samples. The green boiled flour sample had the least wetability (9.00s), while the red soaked flour sample had the highest wetability (270.00s), and was significantly higher than the wetability of all the flour samples. The red boiled flour sample had the highest value (4.80g/ml), and was significantly higher than water absorption capacity of other samples. The red roasted flour sample had the highest viscosity (1 14.00mpals),and was significantly higher ) than other flour sample, while that of green control flour sample and green boiled flour sample had the least viscosity of (96.70mpals) respectively. The amylopectin ratio increases with the various treatment given to each cultivar, from (70.60% and 73.68%) of the two controls, to (74.28%, 75.40%, 76.38%, 77.24%, 80.58%. and 81.76%) of other samples respectively. With green roasted flour sample having the highest ratio of (8 1.76%), and was significantly higher (p<0.05) than other treated flour samples. The amylose ratio decreases as the amylopectin, ratio increase, with green roasted flour sample having the least amylose ratio (18.24%), and that of red control flour sample having the highest ratio (29.40%) the red control flour sample had the value (27.8.17Rvu), and was sigiificantly higher (> than other samples, while red boiled flour sample had the least peak value (108.58RVU). The pasting temperature of red soaked flour sample had the least peak value (82.45°C), while that of red control flour sample had the highest pasting temperature (85.12°c). and was significantly higher han other samples. Red roasted flour sample recorded the highest set back value (124.08Rvu), while that of red boiled flour sample had the least set back value (55.58Rvu). Green roasted flour sample had the least break down value (22.08Rvu), while green boiled flour sample had the highest value of breakdown (48.75Rvu) and was significantly different ) from all other samples. The sensory evaluation of the cookies produced with Dioscorea bulbifera flour was compared with that produced with wheat flour. The panelist liked the taste of the cookies produced with Dioscorea bulbifera flour was disliked moderately (3.60). There was no significant different in the texture of the two samples of cookies produced, while generally, the panelist like the cookies produced with wheat flour very much (8.00), and that produced with Dioscorea bulbifera was liked slightly by the penalist.