Premium
Viscosity studies on the polysaccharide gum from Rhizobium strain CB744
Author(s) -
Beyer Richard,
Melton Laurence D.,
Kennedy Lawrence D.
Publication year - 1987
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740390208
Subject(s) - chemistry , xanthan gum , viscometer , viscosity , thixotropy , guar gum , polysaccharide , rheology , food science , tragacanth , apparent viscosity , natural gum , aqueous solution , sucrose , thickening agent , reduced viscosity , intrinsic viscosity , locust bean gum , chemical engineering , biochemistry , organic chemistry , materials science , thickening , polymer science , engineering , composite material , polymer
Abstract The apparent viscosity of aqueous solutions of polysaccharide gum from the nitrogen‐fixing bacteria Rhizobium strain CB744 has been determined to ascertain the gum's potential in commercial applications as a food conditioner. Solutions of the rhizobium gum had a viscosity that was dependent on the shear rate and showed thixotropic behaviour. The rhizobium gum solutions had an apparent viscosity of 0·05 Pa s at a concentration of 0·4% and 0·16 Pa s at a concentration of 1·0% when measured at 60 rev min −1 with a Brookfield Synchro‐Lectric viscometer at 15°C. The viscosity of the gum solution showed a moderate decrease with decreasing pH, while Sn 2+ and Ca 2+ did not have any effect. Interaction with other common food components was examined by adding sucrose, salt and polysaccharide food additives. Addition of sucrose (15%, w/v) reduced the viscosity by about 30%. Up to 2% NaCl had little effect but 3% NaClgave a considerable reduction in the viscosity of the gum. Addition of guar or xanthan gum did not produce a synergistic effect. Pasteurisation and slow freezing had a pronounced and irreversible effect on the viscosity of gum solutions.