Effect of ozone treatment on the physical, microbiological and sensorial properties of Spanish-style table olives

Ozone has been widely used in the food industry as an effective antimicrobial agent. In this study the possibilities of using ozone in table olive preservation was investigated for the first time. For this purpose, the Domat variety of table olives was processed according to the Spanish style and treated with aqueous ozone for 5, 10, and 20 minutes at 0.5, 1, 2 and 4 ppm. The effects of ozonation on the microbiological, physical and sensory characteristics of the table olives were evaluated during the storage period (up to 180 days). The pH, color and firmness of the ozone treated table olives showed higher stability. Statistically significant reductions in the total bacteria and yeast/mould counts were obtained (p < 0.05). Enterobacteriaceae and Escherichia coli were not found in the samples. After 60 days of storage the control samples (ozone untreated olives) obtained low values for sensory analysis, and did not meet market requirements. The results indicate that treating green table olive with ozon (1 ppm concentration) for 10 min in aqueous form reduces the microbial population without any negative effects on the firmness, color (L*, a* b*) or sensory attributes of the table olives.