Optimization for ultrasound extraction of polysaccharides from mulberry fruits with antioxidant and hyperglycemic activity in vitro

Single-factor experiment and Box-Behnken design (BBD) were applied to optimize the ultrasound-assisted extraction of mulberry fruits polysaccharides (MFP). Under optimum conditions: ratio of water to raw material 40.25, extraction temperature 69 degrees C, ultrasonic power 190 Wand extraction time 75 min, the MFP yield was 3.13% (+/- 0.07%), in accordance to the predicted value of 3.04%. The mulberry fruits polysaccharides fractions was obtained by deproteinization (MFP-1), followed by decolorization and deionization(MFP-2). Carbohydrate content in MFP, MFP-1 and MFP-2 was 58.61% (+/- 1.47%), 69.98% (+/- 0.91%), 81.18% (+/- 1.29%), as well as proteins was estimated 16.50% (+/- 0.86%), 1.57% (+/- 0.63%), 1.02% (+/- 0.18%), respectively. The FT-IR indicated that MFP, MFP-1 and MFP-2 were acidic polysaccharides. The MFP-1 exhibited the strongest antioxidant activity, while MFP-2 showed the strongest hyperglycemic activity in vitro. This may be caused by their different compositions and physical properties in the different mulberry fruit polysaccharides fractions. (C) 2015 Elsevier Ltd. All rights reserved.