title: Structure and rheological characteristics of fucoidan from sea cucumber Apostichopus japonicus.
abstract: Sea cucumber is a traditional health food consumed in East Asia. In this study, fucoidan from sea cucumber Apostichopus japonicus (Aj-FUC) was isolated, and its structure and rheological characteristics were elucidated for the first time. Aj-FUC was a branched polysaccharide mainly composed of a novel repeating unit [α-L-Fucp2(OSO3(-))-1 → 3,(α-L-Fucp-1 → 4-α-L-Fucp-1 →)4-α-L-Fucp2(OSO3(-))-1 → 3-α-L-Fucp2(OSO3(-))], clarified by using a combination of infrared spectroscopy, methylation analysis, enzymatic degradation and nuclear magnetic resonance. In steady shear measurement, Aj-FUC manifested a non-Newtonian shear-thinning behaviour at low shear rate (1-100 S(-1)) while exhibiting a non-Newtonian shear-thickening behaviour at high shear rate (100-1000 S(-1)); salts had limited impact on its flow curve. Comparative study on viscosity and rheological behaviour of Aj-FUC and a linear fucoidan extracted from sea cucumber Acaudina molpadioides suggested that the presence of branch structure might significantly influence the rheological characteristics of fucoidan.
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; ARC Centre of Excellence in Plant Cell Walls, School of Chemical Engineering, University of Queensland, Brisbane 4072, Australia.
authors.forename: Long
authors.initials: L
authors.lastname: Yu
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
authors.forename: Changhu
authors.initials: C
authors.lastname: Xue
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China. Electronic address: changyg@ouc.edu.cn.
authors.forename: Yaoguang
authors.initials: Y
authors.lastname: Chang
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Hu
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Xu
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Ge
authors.affiliation: Department of molecular Engineering, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
authors.forename: Guanchen
authors.initials: G
authors.lastname: Liu
mesh_terms: D000818:Animals; D009682:Magnetic Resonance Spectroscopy; D011134:Polysaccharides / Q000737:chemistry*; D012212:Rheology; D012616:Sea Cucumbers / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D011134:Polysaccharides; C007789:fucoidan
keywords: Apostichopus japonicus; Fucoidan; Rheological behaviour; Sea cucumber; Structure; Viscosity