Microbial Contamination of Fruit and Vegetables and Their Disinfection

Abstract

We evaluated the microbial contamination of 17 types of vegetable and 10 types of fruit after 30-s washing with tap water with and without subsequent disinfection by 10-min immersion in 0.01% (100 ppm) sodium hypochlorite. The mean microbial contamination level of 9 types of leafy vegetable was 2.8×10⁵ colony-forming units (CFU)/g after washing with water and 3.4×10⁴ CFU/g after washing followed by disinfection. The mean microbial contamination level of 8 types of nonleafy vegetable was 3.4×10⁴ CFU/g after washing with water and 1.0×10⁴ CFU/g after washing followed by disinfection. The mean microbial contamination level of 10 types of unpeeled fleshy fruit was 9.3×10³ CFU/g after washing with water and 1.3×10³ CFU/g after washing followed by disinfection. The contaminants in vegetables and unpeeled fruit were similar after washing and after washing followed by disinfection, including Pseudomonas fluorescens and Pseudomonas aeruginosa. The contamination did not markedly decrease even after disinfection with sodium hypochlorite. However, the flesh of each type of peeled fruit showed no or only low levels of contamination (≤10 CFU/g), probably caused by the transfer of microorganisms from the skin of fruit via fruit knives.