Examining the physicochemical, functional and rheological properties in flours of farmers’ 7 key yam (Dioscorea spp.) varieties in Ghana to enhance yam production

Yam (Dioscorea spp.) is an important tuber crop in Ghana with high industrial potential. However the suitability of some yam varieties for diverse culinary and industrial purposes have not been widely studied to inform in their production. This study determined the physicochemical, functional and pasting characteristics in flours of farmers’ 7 key varieties of Dioscorea rotundata (white yam) and Dioscorea alata (water yam). Colour, pH, proximate composition, solubility index, swelling power and pasting properties were determined. Flours from the yam varieties were light in colour and fairly neutral in pH (6.3–6.6). Crude protein levels were between 3.7% for matches and 5.9% Serwah varieties, whereas crude fat was less than 0.5% and the mean ash content was 2.1%. Although significant differences existed between the flours, no clear trend was established to differentiate between D. rotundata and D. alata varieties based on their proximate composition. Swelling power (SP), solubility index (SI) and water absorption capacity (WAC) of the flours differed clearly. D. rotundata varieties had a relatively higher SP (12.5%) and WAC (7.1%), whereas D. alata (20.1%) had the highest SI. Significant differences (p < 0.05) in pasting behaviour were observed. Apart from Serwah and Mutwumudoo varieties, higher peak viscosity and positive retrogradation tendency were observed in the D. rotundata varieties. Among the 7 varieties, pastes from Akaba and Pona varieties were the most stable. The study has revealed that the properties of these varieties of Ghanaian yams make them suitable in diverse culinary and industrial applications.