Darkening of brined olives by rapid alkaline oxidation

Alkaline oxidation of olives called Californian process is a recommended method of the International Olive Oil Council that generally uses three to five lye treatments. The present investigation was carried out to reduce the number of lye treatments to one and consequently minimize the process duration to about 24 h, preventing the health hazards and environmental pollution. Results revealed that no significant differences were noted between the two cultivars used in this study (Gordal and Ladoelia) in response to ferrous gluconate concentration. Ferrous gluconate (0.4\%) should be added during the fixation to stabilize the color produced during air injection. Optimum fixation time was 8 and 12 h for Ladoelia and Gordal cultivars, respectively. When the oxidized black olives were stored in hermetically sealed containers for 4 months in slight brine at different pH values, results revealed that pH 5 was more suitable for maintaining color intensity and firmness of the olives.