Abstract

The influence of traditional and modified soaking methods and varietal difference of sorghum [Sorghum bicolor (Linn.) Moench] grains on the physicochemical properties and consumers’ acceptability of ogi was investigated. Three sorghum varieties (SAMSORG-14, SAMSORG-41 and SAMSORG-42) were used for the study, and each was subjected to three grain-soaking methods (SGW-72, PBW-24 and IBG5-24) after which ogi was produced and then oven-dried (55°C for 18 h). The pH of sorghum ogi prepared from IBG5-24 method was statistically higher (p<0.05) than those from others while it exhibited a correspondingly lowest total titratable acidity. The water absorption capacity (252 to 293%) of ogi also varied with respect to the grain varieties and soaking methods applied. The pasting properties of ogi samples gave significantly varied values (p<0.05) with respect to grain varieties and soaking methods, and these include peak viscosity (560 to 1311 cP), breakdown viscosity (117 to 317 cP), final viscosity (801 to 1571 cP) and setback viscosity (358 to 577 cP). The lightness index (L*-value) of ogi from IBG5-24 method was statistically lower (p<0.05) than that of others while both the swelling capacity and solubility index of ogi samples exhibited increasing values with the elevation of temperature of heating. The sensory quality rating of sorghum gruel (re-constituted and boiled ogi) revealed that ogi from ‘SAMSORG-42 (PBW-24)’ was rated the highest in terms of colour, taste, consistency, aroma and overall acceptability though not significantly different (p<0.05) from samples of ‘SAMSORG-14 (PBW-24)’ and ‘SAMSORG-41 (PBW-24)’. Grain-soaking methods and varietal difference have therefore been shown to influence the physicochemical characteristics and consumers’ preference of sorghum ogi.

Key words:  Sorghum, ogi, drying, physicochemical, soaking technique.