EXTRACTION DE POLYSACCHARIDES PARIETAUX DES NOYAUX DE DATTES VARIETE GHARS

Abstract

The main objective of our study is the valuation of date pits, considered as a widely available lignocellulosic biomass. As a preliminary step, we analyzed the chemical composition of the dates pits powder, about lipids, proteins and ash content, followed by the extraction of the polysaccharides. The results show that raw date pits powder contains 9% moister, 2,23% ash, 8,25% proteins, 6,58% oil expressed to dry weight. After delignification with sodium chlorite solution, we carried out the solubilization of the hemicelluloses by sodium hydroxide solutions at increasing concentrations 5%, 10% and 17,5 %. The raw date pits of variety «Ghars» is composed of 6,42% insoluble-lignin, 43,48% hemicelluloses, and 12,48% cellulose. The polysaccharides are hydrolyzed by two methods: the first one is the reduction / acetylation method and the second is the method of methylglycosides-O-trimethyls (TMS), then they are analyzed by gas chromatography to determine the quality and quantity of the sugars. The results indicate that mannose is the majority sugar, followed by galactose and glucose. The extraction of hemicelluloses shows that raw date pits of Ghars variety is composed of glucomannan with the ration Man: Glc of 3:1.