18A-28 |
|
S. SIMSEK1, B. Mert2, O. H. Campanella2, and B. L. Reuhs1. (1) Dept. of Food Science, Purdue Univ., Whistler Center for Carbohydrate Research, 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, (2) Dept. of Agricultural & Biological Engineering, Purdue Univ., 1146 Agricultural & Biological Engineering Bldg., West Lafayette, IN 47907-1146 Succinoglycans are bacterial exopolysaccharides (EPS) with an octasaccharide repeating unit, composed of glucose and galactose in a molar ratio of 7:1, and non-carbohydrate substutients, including pyruvate, succinate and acetate. The temperature-dependent rheological behaviour of succinoglycan has been reported to be pseudoplastic in aqueous solution and it exhibits a conformational transition between a disordered form and an ordered conformation. The rheological characteristics of succinoglycan may differ from source to source and, therefore, for future applications, it is important to relate the functional properties to the degree of polymerization and nature of the substutients. Our objective was to characterize the succinoglycans produced by four different strains of a gram-negative soil bacterium and relate the chemical properties to the rheological properties. High Performance Liquid Chromatography was used to estimate the ratios of high molecular weight (HMW) to low molecular weight (LMW) EPS, and Nuclear Magnetic Resonance Spectroscopy was used to determine the abundance of the non-carbohydrate substutients. The rheological properties were determined using a broad band oscillatory sequencing flow technique. We observed that each strain produces succinoglycan with different ratios of HMW to LMW and that there is a direct relationship between the content of HMW components and the viscosity of the EPS. It was also found that each strain produces succinoglycan with various degrees of succinylation, which results in different rheological properties. These results showed that the production of EPS with specific and desirable rheological properties can be engineered for the commodity and food industries.
Session 18A, Carbohydrate: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |