Purpose
The purpose of this paper is to examine the efficacy of microbial elimination using different sanitizers in raw vegetables (cherry tomatoes, spring onions, Chinese chives, and chicory) and to analyze the efficacy of Escherichia coli O157:H7 reduction by type of sanitizer and vegetable.
Design/methodology/approach
To assess the sanitizing effects of microbial elimination by variety of vegetable, the samples were grouped into four different washing methods: control (no sanitizer), 100 ppm chlorine, 100 ppm electrolyzed water, and 200 ppm electrolyzed water after prewashing. Subsequently, quantitative microbiological experiments were conducted to assess aerobic mesophilic plate count (APC), coliform, E. coli, and Bacillus cereus, and sensory changes of the sanitized vegetables were tested. Thereafter, measurement of the sanitizing effects on bacterial reduction after inoculation with E. coli O157:H7 was conducted.
Findings
The microbial levels of four types of vegetables ranged from 3.37 to 5.24 log CFU/g for APC, 2.41 to 5.57 log CFU/g for E. coli, 0.25 to 5.40 log CFU/g for coliform, and 0.83 to 5.44 log CFU/g for B. cereus. After three types of sanitizing treatments, microbial reduction effects showed 0.94-1.84 log CFU/g for APC, 0.56-1.00 log CFU/g for E. coli, 0.18-1.26 log CFU/g for coliform, and 0.56-1.23 log CFU/g for B. cereus (p<0.05). In sensory evaluation, there were no significant differences in taste and flavor between with and without sanitizing treatments. Regarding bacterial reduction after inoculation with E. coli O157:H7, the microbial reduction on vegetables was shown to be in the range of 0.27-1.57 log CFU/g with 100 ppm sodium hypochlorite, 0.66-3.07 log CFU/g with 100 ppm electrolyzed water, and 0.79-2.55 log CFU/g with 200 ppm electrolyzed water. Chicory, cherry tomato, and spring onion showed significant reduction levels of E. coli O157:H7 after sanitation (p<0.05).
Originality/value
This study revealed that different sanitization methods are required for different types of vegetables. Electrolyzed water treatment (100 ppm) is a more effective and safe method of washing raw vegetables. Given that the main purpose of sanitizing fresh-cut produce is to maximally reduce microorganism levels, different methods of sanitizing fresh-cut produce with an adequate washing method should be used according to vegetable type.
