Ultrasonic extraction, structural characterization, physicochemical properties and antioxidant activities of polysaccharides from bamboo shoots (Chimonobambusa quadrangularis) processing by-products

In this study, a novel polysaccharide (PCPs) was obtained from bamboo shoots (Chimonobambusa quadrangularis) processing by-products through the ultrasonic-assisted extraction (UAE) and Sephadex G-100 size-exclusion chromatography purification. By using a Box-Behnken design (BBD) to optimize the parameters for extracting the crude PCPs with UAE, the maximum yield of crude PCPs (8.76%) was obtained under the optimal extraction conditions as follows: ratio of water to raw material 20.2 mL/g, extraction temperature 49 °C, ultrasonic power 240 W, and extraction time 40 min. Structurally, PCPs was identified as hetero-polysaccharides, which was composed of Man, Rha, GlcA, GalA, Glc, Gal, Xyl, and Ara in a molecular ratio of 1.00:2.05:2.28:2.36:15.76:49.06:16.70:39.86. The molecular weight distribution analysis showed that PCPs had three components with molecular weights of 136.1, 29.7 and 8.3 kD, respectively. The glycosidic linkage analysis showed that PCPs contained 1 → or 1 → 6 glycosidic linkages (35.1%), 1 → 2 or 1 → 4 glycosidic linkages (14.8%), and 1 → 3 glycosidic linkages (50.1%). conformations. The obtained results revealed that PCPs with a semi-crystalline structure exhibited important functional properties including the repose angle, swelling index (SC), water retention capacity (WRC), and oil retention capacity (ORC). The viscoelastic property of PCPs system exhibited a gel-like behavior with storage modulus G′ always being higher than loss modulus G″. PCPs displayed excellent thermal stability as assessed by rheology and TGA/DSC. Furthermore, PCPs exhibited good chemical antioxidant activities in DPPH, ABTS and hydroxyl radical scavenging abilities, and metal chelating activity.