Effect of treatments with UV-C light and electrolysed oxidizing water on decontamination and the quality of Gemlik black olives

Abstract

The efficacy of ultraviolet-C (UV-C), electrolysed oxidizing water (EOW) and sodium hypochlorite (NaOCl) solution was investigated as non-thermal processes for the surface decontamination of olives. Olives were irradiated at different UV-C doses (0–4770 mJ/cm2) and washed with EOW and NaOCl solutions at different free chlorine concentrations (15, 30, 50, and 80 mg/L). The maximum reduction in microbial load was obtained at 80 mg/L concentration and 4770 mJ/cm2 for washing and irradiation treatments, respectively. L* (lightness), a* (redness) and b* (yellowness) values as well as sensorial attributes were not affected by the UV-C treatments. Our results emphasize that UV-C radiation is effective in reducing surface initial microbial load without any sensorial changes for all doses applied. Nevertheless, with increasing UV-doses, the reduction rate increased. All chlorine concentrations of EOW and NaOCl solutions were effective in reducing surface microbial load compared to control. However, in terms of microbial reduction there was no significant difference among chlorine concentrations except for the yeast and mould count.