Pectin separation from sugar beet juice as affected by the pH, amount of Al2(SO4)3 and use of zeta potential/residual turbidity measurement

Abstract

Impurities in the diffuse juice of sugar beet, especially pectins, interfere with the crystallization of sucrose. The purpose of this paper is to examine the properties of Al2(SO4)3 as an alternative coagulant, considering that the use of lime in the sugar industry requires a large amount of this commercial coagulant. The optimal pH-value interval in a pectin solution (0.1 % wt.) was obtained for producing stable, highly charged forms of hydrolysis of Al2(SO4)3, which facilitate a successful pectin precipitation. The measurements of residual solution turbidity and zeta potential were performed in the study. In the pH range of 3 to 9, the zero zeta potential at which the pectin particles were discharged was pH ~ 6.6. This value was less than the pH value for achieving the minimum solution turbidity (pH ~ 7.5). Both methods of measurement indicated that the pH range 6.6 - 7.5 provided the optimal condition for the highest yield of pectin separation. Measuring the zeta potential was found to be a more effective method than monitoring the turbidity of pectin solution.

Keywords

• aluminium sulphate
• pectins
• ph
• zeta potential
• residual solution turbidity