Effect of processing methods on functional, pasting properties of flours and sensory evaluation of “Amala” made from different yam cultivars

The effect of processing methods on the functional, pasting properties of flours and sensory evaluation of “amala” made from three different cultivars of yam were determined using standard analytical methods. The three cultivars of yam namely; Dioscorea caynensis “Amula and Lasinrin) and Dioscorea alata   (Cote divoire) were processed using three different methods as following; (a) parboiling with steep water (omi-ogi) in aluminium pot and local clay pot (b) parboiling with clean water in aluminium pot and local clay pot (c) heating steep water omi -ogi and clean water separately at 60°C and blanching sliced yam with it in plastic bucket. The functional and sensory properties of the yam flour obtained from the three processing methods were determined using standard analytical method. Data collected were analyzed statistically to determine the Analysis of Variance (ANOVA) and the means. There were significant differences (P<0.05) in the result obtained. The bulk density, water absorption capacity, wettability, oil absorption capacity and swelling index of the yam flour ranged from 0.33±0.01 to 0.49±0.03g/ml, 7.50±0.44 to 0.50±0.44g/ml, 36.67±11.55 to 178.33±2.89secs, 1.47±0.23 to 7.40±1.06g/ml and 1.10±0.01 to 1.82±0.03g/g respectively. The peak viscosity, trough, breakdown, final viscosity, setback, peak time and pasting temperature of yam flour ranged from 1783.00±7.07 to 3682.00±2.83 cP, 1691.00±4.24 to 3533.50±3.54cP, 27.50±2.12 to 195.00±7.07cP, 2351.00±1.41 to 4332.50±3.54cP, 420.00±7.07 to 799.00±1.41cP, 7.03±0.04 to 5.10±0.14cP, 81.35±0.92 to 89.10±0.14cP respectively.  The appearance, colour, taste, texture and overall acceptability of the “amala” ranged from 3.70±1.08 to 8.65±0.75, 3.70±1.03 to 8.60±0.82, 3.50±1.19 to 8.20±1.01, 3.35±1.04 to 8.50±0.95 and 3.35±0.75 to 8.60±0.75 respectively. The LLPSW (cultivar “Lasinrin” processed with local clay pot and steep water “omi-ogi”) had the highest water absorption capacity, LAPOW (cultivar “Amula” processed with aluminium pot and clean water) had the best overall acceptability. Water absorption capacity measures the extent of water retention in yam flour.  It can be concluded that yam flour processed with LCPSW was the best flour from the above results on water absorption capacity.