Fractionation of sugar beet pulp by introducing ion-exchange groups

Sugar beet pulp (SBP) was chemically modified with the goal to utilize this method for the preparation of water-soluble polysaccharides. Yields of the trimethylammoniumhydroxypropylated (TMAHP) polysaccharide fractions prepared under vacuum in absence of NaOH or KOH, as well as their molar masses, were higher than those obtained when the samples were only extracted with hydroxide at ambient pressure. The hydroxypropylsulfonated (HPS) fractions extracted at ambient pressure with NaOH had higher yields and molar mass than the TMAHP fractions extracted under vacuum with KOH. Introduction of both ion-exchange groups in one step under vacuum with NaOH gave better yields than with KOH, but smaller than for the solely sulfonated sample. The molar masses of chemically modified fractions were smaller than those extracted only with alkali or water. According to the monosaccharide composition all the fractions are mixtures of arabinogalactans and rhamnogalacturonoans.