Clarification of Citrus Juice is Influenced by Specific Activity of Thermolabile Pectinmethylesterase and Inactive PME‐Pectin Complexes

Thermolabile pectinmethylesterase (PME) from Valencia orange pulp was extracted, partially purified by cation exchange chromatography (IEX), and added to reconstituted orange juice at 2 units/ml. Of the juices that clarified, %T increased, cloud particle size increased and % degree of esterification (DE) decreased in the 15 d storage study. The rate of clarification was most rapid for juices with added PME extracts that never bound Hi‐Trap SP and contained 36 and 27 kDa peptide, intermediate for crude extracts of PME not applied to IEX, and lowest for PME extracts that bound Hi‐Trap SP and contained 36 and 13 kDa peptide. These results suggest that PME‐pectin complexes and low peptides moderate PME activity and juice clarification.