Optimization of extraction process and characterization of water-soluble polysaccharide (Galactomannan) from Algerian biomass; Citrullus colocynthis seeds

In this work, the optimization of extraction of polysaccharides from Citrullus colocynthis curd polysaccharides (CCPs) is investigated by using the analysis of variance. For this aim, a chemical extraction method has been developed in order to be able to isolate CCPs at high level of purity. The extraction was performed by using boiling water at different extraction times (30, 60 and 120min), extraction temperatures (50, 75 and 100 degrees C), and a material ratio (30, 60 and 100g/ml), for maximum polysaccharide extraction. The 3-D response surface plot and the contour plot derived from the mathematical models are used to determine the optimal conditions. The optimum extraction conditions are as follows: extraction temperature 100 degrees C, extraction time 120min and the ratio of water 30ml/g. Under these conditions, the experimental final mass is 210.6mg which is very close to the predicted value (209.46mg) with a regression coefficient of 94.01%. In addition, the existence of the polysaccharide has been confirmed by the characterization of the galactomannan obtained from C. colocynthisis obtained by Fourier transform infrared-attenuated total reflection, IR-Raman spectroscopy and X-ray diffraction.