Nutritional Composition of Flour Blends from Water Yam, Yellow Maize and African Yam Bean

Adequate and proper understanding of the nutritional composition of different flour materials is important in their use in the production of baked food materials. The proximate composition of water yam-yellow maize and African yam bean flour mixtures was therefore evaluated in this study. Standard procedure for dry-milling unit operation was used in the flour processing. Flour samples were blended in different ratios to form the following composite samples: AFK which comprised of 30% water yam (WY):40% yellow maize (YM):30% African yam bean (AYB); BGL which comprised of 40WY:30%YM:30%AYB CHM comprising of 50%WY:20%YM:30%AYB; DIN comprising of 60%YM:10%YM:30%AYB and control treatment comprising of 100%WY. Crude protein content ranged from 4 to 22.50%; fat content ranged from 1.80%; ash content ranged from 7.00%; moisture content ranged from 6.00 to 10.00% carbohydrate content ranged from 50.43 to 80.90% and energy content ranged from 331.50 to 356.35%ked. Addition of yellow maize and African yam bean statistically (p<0.05) increased the protein, fat, fibre, ash, moisture and energy content of flour blend but statistically (P<0.5) reduced the carbohydrate content. Flour sample DIN found to be adequate for both children and adult consumption of the flour when compared to the Codex Alimentarius Commission [1].

Pasting Properties of Flour Blends from Water Yam, Yellow Maize and African Yam Bean Seeds

Pasting properties of flour blends from water yam, yellow maize and African yam bean were investigated in this study. Peak viscosity ranged from 133.50 to 166.25RVU, Trough viscosity ranged from 85.08 to 135.20RVU, break down viscosity ranged from 28.17 to 50.58RVU, final viscosity ranged from 5.05 to 5.49 min and pasting temperature ranged from 80.25 84.15oC. Addition of yellow maize and African yam bean affected (p<0.05) the peak viscosity, trough viscosity, break down viscosity, final viscosity, and setback viscosity in different trends. However, peak time and peak temperature of the flour sample were not statically (p<0.05) affected by the blend ratio in this study. Amongst the flour samples investigated in this study, flour sample DIN (60%WY:10%YM:30%AYB) showed promise for value added products such as noodles among other flour products. They flour sample adjusted to be the best sample could be used as a good replacement for wheat flour and when achieved, it will reduce the cost of importation.

Physicochemical and Pasting Characteristics of Water Yam (D. alata) in Comparison with Pona (D. rotundata) from Ghana.

The physicochemical and pasting characteristics of 18 varieties of Dioscorea alata (an underutilized yam species) were determined in comparison to pona, (a local and most preferred Dioscorea rontundata variety in Ghana) to contribute to knowledge base of D. alata for product diversification and further improvement. Tubers were randomly selected and moisture content determined before processing the remaining to flour for physicochemical and pasting characteristics. The results showed that test varieties had significantly (p<0.05) higher moisture and protein contents, higher peak time and pasting temperature but lower dry matter and starch content, lower swelling power and pasting viscosities in comparison with pona. Peak viscosity ranged from 74.80 to 284.60 RVU, trough (66.85 to 258.65 RVU), and breakdown (19.50 to 311.50 RVU). Peak time and pasting temperatures were 5.15 - 7.00 min and 83.60-90.10OC respectively. Pona had 291.17 RVU as peak viscosity, 186.17 RVU troughs, 105.00 RVU breakdown and 422.75 RVU final viscosity. Others were: setback (236.58 RVU), peak time (4.73 min) and pasting temperatures (79.88 oC). The physicochemical properties in conjunction with the pasting properties of the test varieties suggest the presence of strong bonding forces within their starch granules. Pastes from test varieties were relatively more stable when cooked hence will have a lower tendency to undergo retrogradation during freeze/thaw cycles than the reference variety. The study has shown significant variations among D. alata varieties and between the D. alata and pona. This could lead to selection and improvement of D. alata varieties for specific food applications to stimulate their production and utilization.