Simultaneous degumming and production of a natural gum from Crotalaria juncea seeds: Physicochemical and rheological characterization

Abstract The oil extracted from Crotalaria juncea (Sunn-hemp) contains 70% of gum. Several methods of degumming are attempted in order to maximize the yield of gum. During appropriate water induced degumming, about 95–98% of phosphatides are separated. The maximum oil yield for two types of degummimg processes are 0.59% and 0.69% corresponding to hot water and pure O-phosphoric acid (19.88 N) treatment respectively. The % oil yield obtained for TOP degumming is about 0.78%. Physico-chemical characteristics of the isolated gum such as moisture, ash, protein, fat and aqueous solubility along with FTIR and TGA analysis are studied in order to evaluate the effect of extraction process. The behaviour of gum on the molecular scale is evaluated through alcohol treatment. Chromatographic analysis determines the monosaccharide content of the gum with glucose: xylose: arabinose::54: 34:1. Rheological characterization shows that the juncea gum solutions are shear rate dependent and the behaviour is shear-thinning (or pseudoplastic). Results show that the temperature dependent viscosity decreases with increasing shear rate.