Studies on the steady shear flow behavior and chemical properties of water-soluble polysaccharide from Ziziphus lotus fruit

The extraction of water-soluble polysaccharide from Ziziphus lotus fruit (WPZL) was performed by ultrasonic-assisted extraction method. A Box-Behnken design (BBD) was applied to evaluate the effects of three independent variables (ultrasonic power (Xi: 70-100 W), extraction time (X-2: 10-30 min), extraction temperature (X-3: 55-95 degrees C), and water to raw material ratio (X-4: 5-25)) on the extraction yield of APH. The effect of temperature and concentration on flow behavior of gum solution was studied. WPZL solutions exhibited shear-thinning non-Newtonian flow behavior for concentrations above 0.5% (w/v). The viscosity of fully hydrated gum solutions decreased as temperature increase. The correlation analysis of the mathematical-regression model indicated that quadratic polynomial model could be employed to optimize the extraction of WPZL. The optimal conditions to obtain the highest extraction of WPZL (13.398 +/- 0.019%) were as follows: ultrasonic power, 88.77 W; extraction time, 29.96 min, extraction temperature, 77.73 degrees C and water to raw material ratio 24.44 mL/g. (C) 2014 Elsevier B.V. All rights reserved.