Effect of gum arabic concentrations on drying kinetics, anthocyanin degradation and product qualities of purple rice bran extract dried by foam-mat technique

Abstract

This investigation aimed to study the effect of gum arabic on the drying characteristics, degradation rate of anthocyanin, and quality of foam-mat product from purple rice bran. Four different levels of gum arabic (GA) were applied (5-20%), with the control sample (without using gum arabic) for the foaming process. Foaming properties, including foam expansion, foam stability, and foam density, were determined and showed that the fluctuation was found when different contents of gum arabic were used. In particular, the highest value of foam expansion (386.75±9.35%) and foam stability (94.44±0.09%) was found at a level of usage GA of 10%, while the lowest foam density (0.278±0.021%) was observed. Empirical models were applied to predict the change of moisture content during the drying process, showing that the Page model was the fittest and gave the best prediction (R2 > 0.98) at various concentrations of gum arabic. Besides that, following first-order kinetic, the lowest rate of anthocyanin degradation occurred when the concentration of GA was used at the level of 10%. Pearson’s correlation showed the negative effect between anthocyanin degradation rate and drying rate of the constant of the Page model. Moreover, dried purple rice bran extract was added 10% of GA, which presented a high level of anthocyanin (20.34±0.82 mg/100 g), moisture content of 4.26±0.12%, water activity of 0.33±0.11, hygroscopicity of 19.82±0.11 g/100 g, and high acceptance by panelists