title: Effect of a small amount of sodium carbonate on konjac glucomannan-induced changes in wheat starch gel.
abstract: Wheat starch gels were produced with konjac glucomannan (KGM) and low concentrations of Na2CO3 (0.1-0.2 wt% of starch) using a rapid viscosity analyzer (RVA). The gelling properties of wheat starch in varying ratios of KGM and Na2CO3 were characterized by differential scanning calorimetry (DSC), rheometry and confocal laser scanning microscopy (CLSM). A small amount of Na2CO3 resulted in gels with increased elasticity whereas structural ordering during retrogradation was insignificantly affected. Comparison of CLSM images of composite gels revealed that Na2CO3 at 0.2 wt% of starch allowed the formation of fiber-like extensions around scattered swollen granules by KGM and amylose interaction, making swollen granules disperse within the micro phase, which was not typical in CLSM images of gels in the absence of Na2CO3. Dynamic storage modulus and dynamic power law exponent were substantially higher than those observed for the same concentration of KGM in the presence of Na2CO3, supporting the hypothesis that Na2CO3 could promote strong interchain associations between KGM and starch components.
authors.affiliation: Beijing Key Laboratory of Functional Food from Plant Resources, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Beijing Key Laboratory of Functional Food from Plant Resources, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Winkworth-Smith
authors.affiliation: Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Foster
authors.affiliation: Japan International Research Center for Agricultural Sciences, Tsukuba 305-8686, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nirasawa
authors.affiliation: Japan International Research Center for Agricultural Sciences, Tsukuba 305-8686, Japan.
authors.forename: Eizo
authors.initials: E
authors.lastname: Tatsumi
authors.affiliation: Beijing Key Laboratory of Functional Food from Plant Resources, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China. Electronic address: chengyq@cau.edu.cn.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Cheng
mesh_terms: D002152:Calorimetry, Differential Scanning; D002254:Carbonates / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry*; D018613:Microscopy, Confocal; D012212:Rheology; D013213:Starch / Q000737:chemistry*; D014908:Triticum
chemical_list: D002254:Carbonates; D005782:Gels; D008351:Mannans; C022901:(1-6)-alpha-glucomannan; C005686:sodium carbonate; D013213:Starch
keywords: Konjac glucomannan; Na(2)CO(3); Phase separation; Retrogradation; Starch gel