The Effects Of Processing Methods On The Glycemic Index, Chemical And Functional Properties Of Some Selected Tuber Flours

ABSTRACT

Four species of yam; white yam (Dioscorea rotundata), aerial yam (Dioscorea bulbifera), cocoyam (Xanthosoma robustum) and water yam (Dioscorea alata) were analysed for their glycemic indices, chemical and functional properties after subjecting them to four processing operations of boiling, sprouting, frying, roasting and a set was left untreated. Boiled cocoyam (Xanthosoma robustum) among the species was significantly (p<0.05) different  in terms of glycemic index (40.215)%, total starch (52.29%), digestible starch (49.67%),oil absorption capacity (3.09%) and solubility (14.97%) whereas boiled aerial yam was significantly (p<0.05) different  from all the samples in terms of water absorption capacity (4.21%), wettability (20.56%) and dispersibility (73.17%). Boiled white yam was significantly (p<0.05) different in terms of swelling power (9.21%) and bulk density (0.78%). Sprouted water yam was remarkably different (p<0.05) from all the samples in gelation capacity (12.00%), foam capacity (46.67%), foam stability (13.33%) and gelatinization temperature (88.30^oC) while sprouted white yam was significantly (p<0.05) different  in terms of protein content (3.50%) and moisture content (13.40%) while among the processing operations, boiling as a treatment was significantly (p<0.05) different from sprouting, frying, roasting as well as the untreated.