Effect of Drying Temperature on Effective Diffusivities and Protein Dispersibility Indexes of Full Fat Soy Flour

Abstract

The objective of this research is to study the effect of processing temperature on diffusivities of water and protein dispersibility index of full fat soy flour.

Soybean varieties Chiangmai 60 and SJ.4 with initial moisture content of 0.097 and 0.099(dry basis) respectively were dried in a cabinet dryer at loo-150 “C with air velocity of 1.84 m/s. The effective diffusivities which determined by curve fitting were correlated with temperature according to Arrhenius law. The activation energy of Chiangmai 60 and SJ.4 soybean varieties were 48.50 kJ/mol and 45.60 kJ/mol, respectively.

Kinetic analysis on temperature dependent of protein dispersibility index showed that full fatsoy flour had two ranges of activation energy. At temperature below 120 “C the activation energy of Chiangmai 60 and SJ.4 soybean varieties were 29.66 kJ/mol and 23.14 kJ/mol and at temperature over 120 “C were 169.62 kJ/mol and 17 1.94 kJ/mol, respectively.

By using these results to predict the moisture content and protein dispersibility index of real processing which used vibro-fluid bed dryer for drying, it is found that the moisture content of the samples was in good agreement with the predicted one, where as the protein dispersibility index of product was found to be lower than predicted value.