Moisture sorption isotherm characteristics and Taguchi analysis of rice bran extraction parameters

This work determined the moisture sorption isotherm of rice bran and investigated the effects of the pre-treatment method, solvent type, solid–liquid ratio and soaping temperature on extract yield, total phenolic content, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity assay and 2,2′-azino-bis antioxidant capacity assay of rice bran extract. The Taguchi method and L9 (3⁴) orthogonal array were employed in this study. The sorption isotherms of rice bran showed a sigmoidal pattern and displayed type II of van der Waals adsorption. Adsorption and desorption data on rice bran were best fitted using the Henderson model among the six models tested at three temperatures. The net isosteric heat of desorption was higher than the net isosteric heat of adsorption. Based on the analysis of the signal-to-noise ratio, solvent selection effected the largest contribution to the overall performance. Confirmation experiments showed that the optimal combination that contained the four quality attributes was appropriate (error margin <5%) and reproducible.