Extraction, characterization and antioxidant activity of water-soluble polysaccharides from Tuber huidongense

• UAE was firstly applied in extracting process of THWP and being optimized by RSM.
• The crude THWP was purified by Cellulose DEAE-52 and Sephadex G-100 chromatography.
• The average molecular weights of THWP-1 and THWP-2 were analyzed by HPSEC.
• THWP-1 was consisted of Glc, Man and Gal, while THWP-2 was only composed of Glc.
• THWP-1 and THWP-2 showed effective antioxidant activity in vitro.

Single-factor experiment and Box–Behnken design were employed to optimize the ultrasonic-assisted extraction (UAE) of water-soluble polysaccharides from Chinese truffle Tuber huidongense (THWP). The optimal extraction conditions with an extraction yield of 7.17 ± 0.22% crude THWP were determined as follows: ultrasonic power 99.65 W, extraction time 40.39 min, ratio of water to raw material 24.65 mL/g, and extraction temperature 70.1 °C. Two purified fractions, THWP-1 and THWP-2 with molecular weights of 128 kDa and 729 kDa, respectively, were obtained from crude THWP by Cellulose DEAE-52 and Sephadex G-100 chromatography. Monosaccharide component analysis by high performance liquid chromatography (HPLC) indicated that THWP-1 was composed of Glc, Man, and Gal with their corresponding mole percentages of 60.56%, 20.12% and 19.32%, respectively and that THWP-2 contained only Glc. Evaluation of the antioxidant activity in vitro suggested that THWP-1 and THWP-2 had effective scavenging activity of 2,2′-azinobis-(3-ethylbenzothiazolin-6-sulfonicacid) (ABST), hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Accordingly, the polysaccharides from Chinese truffle might serve as a natural antioxidant in functional foods.