Solution properties of the galactomannans extracted from the seeds of Caesalpinia pulcherrima and Cassia javanica: comparison with locust bean gum

The galactomannans from the seeds of Caesalpinia pulcherrima and Cassia jav anica were extracted from the milled seeds in water at room temperature. Bo th products, as well as a commercial sample of locust bean gum (LBG), were purified by precipitation in isopropyl alcohol. The intrinsic viscosity det ermined for LBG, [eta] = 15.2 dl/g, was slightly higher than those for the other two galactomannans. The dependence of the specific viscosity at zero sheer rate on the coil overlap parameter, C[eta], revealed a similar behavi our for the three galactomannans. A master curve was obtained with a critic al concentration, C*, at C*[eta] = 3.3. The slope of the curve in the conce ntrated regime is higher than the values in the range of 3.9-6.6, obtained for the generalized behaviour of several random coil polysaccharides. Dynam ic experiments showed that, at the concentrations studied: the behaviour of the galactomannans was typical of systems with predominant entanglement ne tworks in the region between the terminal and plateau zones of frequency re sponse. The correlation between dynamic and steady shear properties (Cox-Me rz rule) was satisfactory for the three galactomannans. (C) 1999 Elsevier S cience B.V. All rights reserved.