Effect of steaming on properties of yam flour

Abstract

PurposeThe aim of the study is to compare the effect of steaming method and time on the physico‐chemical properties of underutilized Dioscorea dumetorum with three more commonly consumed Dioscorea rotundata, Dioscorea cayenensis and Dioscorea alata.Design/methodology/approachRaw and pre‐gelatinized flour were produced from the yam species. Pre‐gelatinization was done by steaming diced cubes in autoclave at 68,950 Nm‐2 for 5 min and in Barlett steamer at 98±2°C for 10, 20 and 30 min. Flour samples were analyzed for amylose content, swelling index, consistency, solubility, water absorption capacity, and iodine affinity for starch.FindingsThe physico‐chemical properties of the flours were affected by both species and steaming time. Pre‐gelatinization of the tuber reduced amylose content in all the yam species, which reduced further with increase in steaming time. Except for amylose content and iodine affinity for starch, D. dumetorum compared with D. rotundata and D. cayenensis in the parameters that were measured. Samples autoclaved for 5 min had value similar to those steamed in Barlett steamer for 10 and 20 min for all the parameters that were measured, except consistency.Practical implicationsIt is very important to encourage the cultivation and utilization of D. dumetorum because of the high yield and nutritional composition to enhance the nutritional and financial well‐being of the populace.Originality/valuePre‐gelatinization is important as pre‐treatment for yam tubers. Underutilized D. dumetorum could be useful in ingredient formulation for product development, especially as a thickening agent.