EFFECT OF DRYING METHODS ON THE EQUILIBRIUM MOISTURE CONTENT ISOTHERMS OF SOY PULP (OKARA)POWDER

摘要

The present study was aimed to determine the equilibrium moisture contents (M_E)isotherms of okara powders that produced by means of three different drying methods:hot-air, spouted-bed, and freeze dryers. Observations showed that for the temperatures of30, 40 and 50°C, the M_Evalues of okara powders ranged from 1.5 to 24.5% d.b.depending upon the a_w values of okara samples. An increase in a_wvalues of okaraincreased the ME isotherms of okara powders, while the temperature change appeared noto affect the M_Eof okara powders. Freeze-dried powder was more sensitive to thechanges of a_w values than hot-air-dried and spouted-bed-dried okara powders. Fitting offive sorption models to the experimental data revealed that the Halsey equation was themost excellent predictor to the M_Evalues of freeze-dried and spouted-bed-okarapowders. The experimental M_Eof hot-air-dried okara powders was best represented bythe GAB model as indicated by the highest goodness of fit