Physico-chemical properties and protein profiling of gum exudates of Acacia nilotica collected from different agro-climatic zones in India

Abstract

Physico-chemical properties and protein profiling of seventeen Acacia nilotica (babool) gum exudates collected from ten Indian States covering five agro-climatic zones of India were studied to find out the intra-specific variations in their moisture level, total color difference (ΔE), yield %, ash content, elemental level, tannin content (mg/g), specific rotation [], swelling index (%, v/v), viscosity and FT-IR. All the gum exudates showed Newtonian behavior with viscosity being shear rate independent. Gums were thermally characterized using differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). DSC thermogram of gum samples showed presence of a broad endothermic peak at around 90-130 0C and occurrence of glass transition temperature in the range of 60.82-68.62 0C. TGA analysis showed three phases of weight loss indicating that the gum is thermally relatively stable. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of gum samples showed presence of mainly low molecular weight proteins. The observed intra-specific variations in the properties of Acacia nilotica gum exudates collected from different agro-climatic zones of India are presumably due to the effects of difference in their geographical locations, edaphic conditions, climatic factors, botanical sources, season and the age of the tree etc.