CaSO4 and cationic polyelectrolyte as possible pectin precipitants in sugar beet juice clarification

Three pectin preparations were isolated from fresh sugar beet pulp during the 150 min of extraction, at pH values of 1, 3.5 and 8.5. CaSO4 precipitant was added to 100 cm(3) of 0.1 wt.% solution of pectin. Studies were performed with 9 different concentrations of CaSO4 solution (50-450 mg dm(-3)) with the addition of a cationic polyelectrolyte (cationic PAM) in concentrations of 3 and 5 mg dm(-3). The efficiency of pectin precipitation was monitored by measuring the zeta potential of pectin preparations. Optimal amounts of precipitant CaSO4, without the use of a cationic polyelectrolyte, were as follows: 490-678 mg CaSO4/g pectin. After the use of a cationic polyelectrolyte, the optimal amounts of CaSO4 were smaller (353-512 mg/g pectin). These quantities are significantly lower than the average amount of CaO used in the conventional clarification process of sugar beet juice (about 9 g/g pectin of sugar beet juice).