Slightly acidic electrolyzed water combined with chemical and physical treatments to decontaminate bacteria on fresh fruits

Abstract

Effect of sequential combination of slightly acidic electrolyzed water (SAEW) with chemical and physical treatments on bacterial decontamination on fruits was investigated in this study. Effect of treatments on microbial and sensory quality was also analyzed after subsequent storage at 4 °C and room temperature (RT, 23 ± 0.15 °C). Whole apple and tomato fruits were inoculated with cocktail strains of Escherichia coli O157:H7 and Listeria monocytogenes. Uninoculated and inoculated fruits were washed first with distilled water (DW), calcium oxide (CaO), fumaric acid (FA), and SAEW at RT for 3 min. Combinations were performed by adding treatment one at a time to SAEW as following FA + SAEW, CaO + FA + SAEW, and CaO + FA + SAEW + ultrasonication (US) or microbubbles (MB). All the sanitizer treatments resulted in significant (p < 0.05) bacterial reduction compared to DW used as control. Increasing the treatments in combination from FA + SAEW to CaO + FA + SAEW + US resulted in an increased bacterial decontamination. The cavitation induced by ultrasonication in FA + SAEW solution resulted in a higher additive effect in decontamination of Escherichia coli O157:H7 and Listeria monocytogenes compare to the agitation generated by microbubble generator in FA + SAEW solution. CaO + FA + SAEW and CaO + FA + SAEW + US were effective in improving the microbial safety and quality of apple fruits. However, additional treatment of US impacted on the quality of tomato fruits during storage at RT. Therefore, a combination of SAEW with sanitizers (CaO and FA) and mechanical force (Ultrasonication) has the potential to be used in postharvest sanitation processing in the fresh fruit industry.

Keywords: Combined treatments; Decontamination; Fruits; Quality; Slightly acidic electrolyzed water.