ABSTRACT
The Cassia angustifolia seed gum (CAG), a galactomannan, isolated from the seeds of C. angustifolia was subjected to the carbamoylethylation which involved the reaction of CAG with acrylamide in an aqueous medium (water) in the presence of alkali (NaOH) as a catalyst. Alkali concentration, acrylamide concentration, liquor:gum ratio as well as reaction temperature and time were found to affect the extent of carbamoylethylation of CAG (expressed in terms of nitrogen content) and so, these were optimized. Degree of substitution (DS) and reaction efficiency was also determined. FTIR revealed the successful carbamoylethylation of CAG and rheological study conducted on 1 and 2% (w/w) solutions of the carbamoylethyl-CAG not only brought out the non-Newtonian pseudoplastic behaviour, but also high stability of carbamoylethyl-CAG solutions in comparison to solutions of the unmodified CAG.
Subject(s)
Cassia/chemistry , Mannans/chemistry , Mannans/chemical synthesis , Seeds/chemistry , Water/chemistry , Acrylamide/chemistry , Chemistry Techniques, Synthetic , Galactose/analogs & derivatives , Kinetics , Rheology , Sodium Hydroxide/chemistry , TemperatureABSTRACT
The seeds of Cassia angustifolia are a rich source of galactomannan gum. The seed gums possess a wide variety of industrial applications. To utilize C. angustifolia seed gum for broader industrial applications, the carboxymethyl-Cassia angustifolia seed gum (CM-CAG) was synthesized. The gum was etherified with sodium monochloroacetate (SMCA) in a methanol-water system in presence of alkali (NaOH) at different reaction conditions. The variables studied includes alkali concentration, SMCA concentration, methanol:water ratio, liquor:gum ratio, reaction temperature and time. The extent of carboxymethylation was determined as degree of substitution (DS). The optimum conditions for preparing CM-CAG (DS=0.474) comprised 0.100 mol of NaOH, 0.05 mol of SMCA, 80% of methanol:water ratio (as % methanol) and liquor:gum ratio (v/w) of 10:1 at 75 °C for 60 min using 0.03 mol (as AGU) of CAG. Rheological studies showed CM-CAG to exhibit non-Newtonian pseudoplastic behaviour, relatively high viscosity, cold water solubility and solution stability.
