Recovery, chemical and rheological characterization of gum from Assyrian pulm

The extraction of gum from Assyrian pulm fruit (APH) was performed by microwave-assisted extraction technique. A Box-Behnken design (BBD) was applied to evaluate the effects of three independent variables (power of microwave (X1: 50-350 W), extraction time (X2: 20-90 min), and extraction temperature (X3: 50-90 °C)) on the extraction yield of APH. The effect of temperature and concentration on flow behavior of gum solution was studied. The viscosity of 2% APH solution was 0.55 Pa s at a shear rate of 10 s−1 at 20 °C. The viscosity of fully hydrated gum solutions decreased as temperature increase. It was found that increasing the temperature from 10 to 60 °C causing the viscosity to decrease about 87% at shear rate 0.1 s−1 and 98% at shear rate 500 s−1. The correlation analysis of the mathematical-regression model indicated that quadratic polynomial model could be employed to optimize the microwave extraction of APH. The optimal conditions to obtain the highest extraction of APH (18.19 ± 0.26%) were as follows: microwave power, 330 W; extraction time, 80.67 min and extraction temperature, 82 °C.