This study investigates the pretreatments and drying method effects on white yam’s physicochemical, microbial, and sensory qualities. The fresh tubers were washed, (equally) uniformly sliced, pretreated, dried, and processed into flours. The flours were evaluated for physicochemical, microbial, and sensory properties using standard methods. The results showed that all physicochemical parameters examined were significantly (p<0.05) affected by the pretreatments and the drying methods except for the gelatinization temperature. The total viable bacterial count ranged from 362x10-3 to 496x10-3 cfu/ml, 140x10-3 to 284x10-3 cfu/ml, and 282x10-3 to 344x10-3 cfu/ml, respectively for open sun, oven, and solar drying. Aspergillus niger and Aspergillus flavus were isolated in open sun drying, Candida albicans was isolated in both open sun and oven drying, Alternaria was isolated in both open sun and solar drying, while Rhizopus sp. was isolated in all the drying methods considered. Sensory evaluation conducted on the amala revealed that the amala produced from yam flours pretreated with blanching and 0.1% sodium metabisulphite alongside oven and solar drying were preferred by the panelists to untreated and open sun-dried ones. The wide variation observed in the physicochemical properties of the flour samples could serve as a database for the improvement of the yam flour processing.

Keywords: White yam flour, pretreatment, drying methods, physicochemical properties