Characterisation of the turbid particles in the extraction of sugar beet pectins

• The purity of pectin was influenced by the turbid particles.
• The turbidity of the extract was caused by the turbid particles.
• The turbid particles were characterised to be calcium oxalate dihydrate.

This paper was aimed at characterising the insoluble substances (IS) responsible for the turbidity of the extract and impurity of the resulting pectins. Results showed that the IS caused a significant increase in the turbidity of the extract. The IS had bi-pyramidal shapes under the SEM observation. The observed XRD peaks for the IS were similar to those of calcium oxalate dihydrate (COD). Moreover, the IS consisted of mainly oxalate and calcium. Results from the present study indicate the IS is COD. The influence of the IS on the purity of pectin was also studied. The presence of the IS in the pectins indicated the IS can precipitate with pectins during the alcohol precipitation, thereby contaminating the resulting pectins.