Journal Article

Determination of the Functional Properties and Moisture Sorption Isotherm of Dried Soybean Curd

Abstract

Soybean curd was produced with ruwan tsami, lime and aluminum sulphate and dried under the sun at 34 ± 2oC to moisture content of 11%. The dried soybean curd was then characterized in terms of functional properties and moisture sorption characteristics. The bulk density of 0.66kg/m3 for aluminum sulphate, 0.64kg/m3 for lime and 0.68kg/m3 for ruwan tsami were obtained. The Water Absorption Capacity of aluminum sulphate, lime and ruwan tsami were 274.33%, 256.00%, and 252.66% respectively and the Oil Absorption Capacity were found to be 197.67%, 211.00%, and 216.00% respectively. While the Swelling Capacity of the soybean extract for the aluminum sulphate, lime and ruwan tsami obtained were 332.47%, 361.33% and 351.13% respectively. The sorption data were fitted into Oswin equation by plotting a linear curve to estimate the constant c and n of each of the models. These constants were used to extrapolate the equilibrium moisture contents of the samples at various water activity (aw) points. The calculated values were then compared with experimental value and found to compare well and the adsorption Isotherm of the dried soy-curd was plotted and found to correspond to the Flory-Huggins isotherm shape of Type III. The Oswin equation gave high coefficients of determination of fitness of data.

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