Extraction and derivatization of Leucaena leucocephala (Lam.) galactomannan: Optimization and characterization

Water soluble gums also known as hydrocolloids are increasingly finding applications in the pharmaceutical and food industry due to their versatile functional properties. They possess considerable use in food and pharmaceutical industries as emulsifying, thickening and gelling agents. In the present investigation a heteropolysaccharide galactomannan was extracted from Leucaena leucocephala (Lam.) seeds by an aqueous method, characterized for its compositional analysis (mannose: galactose ratio), physicochemical and functional properties (solubility), and mechanical properties. The extracted gum was derivatized to form its carboxymethyl derivative and the method of its derivatization was optimized by varying the reaction parameters. The native and derivatized gum was characterized by FTIR, XRD, DSC, NMR, SEM and elemental analysis, etc. The yield of Leucaena leucocephala galactomannan (LLG) was found to be 20% (w/w). The optimized parameters for carboxymethylation reaction (degree of substitution 0.805) were found to be 6.0 g NaOH, 10.0 g MCA, at 60 °C for 4 h. The physicochemical and functional characteristics of native and derivatized gum suggest its potential role in food and pharmaceutical industries.