IMPACTS OF PRETREATMENTS AND DRYING TECHNIQUES ON THE PHYSIOCHEMICAL, MICROBIAL, AND SENSORY PROPERTIES OF WHITE YAM (Dioscorea Rotundata) FLOUR

Abstract

The impacts of pretreatments and drying techniques on the physicochemical, microbial, and sensory properties of white yam are examined in this study. Fresh tubers were cleaned, pretreated, uniformly sliced, dried, and turned into flour. Physicochemical, microbial, and sensory attributes of the flours were assessed using accepted techniques. The findings demonstrated that, with the exception of the gelatinization temperature, all physicochemical parameters under investigation were significantly (p<0.05) influenced by the pretreatments and drying techniques. The moisture ranged from 3.00 to 11.50%, the bulk density was 0.67 to 0.71 g/mL, the water absorption capacity was 1.80 to 2.47 g/g, the swelling capacity was 27.30 to 70.00%, the gelatinization temperature was 74.00 to 80.00ᵒC, and the least gelation capacity was 8.00 to 14.00%. Compared to solar and oven drying, the total viable bacterial count in open sun dried yam flour was significantly higher (p<0.05). Alternaria was isolated with using open sun and solar drying, Aspergillus niger and Aspergillus flavus were isolated using open sun drying, Candida albicans was isolated with using open sun and oven drying, Rhizopus sp. was isolated using all drying techniques taken into account. The amala produced from yam flour pretreated with blanching and 0.1 percent sodium metabisulphite along with oven and solar drying was preferred by the panellists to untreated and open sun-dried ones, according to the sensory analysis of the amala. The extensive variation in the physicochemical characteristics of the flour samples could be used as a database to enhance the processing of yam flour