USE OF MANGANESE IN RIPE OLIVE PROCESSING

The use of manganese (Mn) salts in various steps of the processing of ripe olives of the Manzanilla cultivar can increase their oxidation ra te and produce darker olives. The best results were obtained by adding a Mn concentrations of 40 mg/l to the storage brine and allowing a pe riod of contact of at least 15 days. Good results were also obtained w hen using a Mn concentration of 100-250 mg/l in a ''desalting'' step b efore darkening, as well as variable periods of contact and temperatur es. When Mn was added to the washing waters after any of the lye treat ments of the darkening step, especially the first one, the effect was also appreciable, although varying degrees of Mn residues in the flesh were found. Addition of Mn to the storage brine and application of th e usual darkening process produced more uniform and darker ripe olives with Mn residue levels at below 30 mg/kg, which is approximately 15% of the recommended daily intake for this metal. Results suggest that t his cation, recognized as GRAS in the USA, may be used as a catalyst i n the darkening of ripe olives if authorized as a processing aid.