Abstract
Different protocols have been used for washing and disinfecting leafy vegetables in Brazilian food services, however its effect on microbial reduction was barely studied. The aim of this study was to evaluate the effectiveness of lettuce washing and disinfecting protocols used by food services. The treatments evaluated were: washing in potable tap water (T1); washing and dipping in potable tap water (T2); washing with potable tap water and dipping in a solution of sodium hypochlorite (200 ppm of free chlorine) for 15 min (T3); and 30 min (T4); washing with potable tap water and dipping in 2% vinegar solution (T5); and 20% vinegar solution (T6). After the treatments, the samples were microbiologically evaluated to measure bacterial reductions. The microbial counts showed that the mean total mesophile reductions were: 0.64 log for T1, 0.75 log for T2, 2.06 log for T3, 2.46 log for T4, 1.68 log for T5 and 1.72 log for T6, and the mean total coliform reductions were: 1.11 log for T1, 1.09 log for T2, 2.29 log for T3, 2.35 log for T4, 1.6 log for T5 and 2.09 log for T6. Based on these results it can be concluded that protocols which used 200 ppm sodium hypochlorite for 15 to 30 min (T3 e T4), were the most effective, followed by treatment with 20% vinegar solution (T6). The latter method, however, turned the lettuce dark during the distribution period.
Highlights
The consumption of vegetables has been rising over the last few years due to a demand for healthier diets
There was significant statistical difference (p < 0.01) between the prices charged for meals in the two districts. This difference suggests that the choice of the two districts was correct, since the purpose was to investtigate lettuce washing and disinfection protocols in different realities
Most of the food services presented specific kitchen utensils for leaf vegetable washing and disinfection, as well as for their display on the buffet
Summary
The consumption of vegetables has been rising over the last few years due to a demand for healthier diets. Lettuce (Lactuca sativa) is the most popular leaf vegetable among Brazilians [1,2]. Vegetables can be potential vehicles of pathogenic microorganisms, contributing to the increasing number of foodborne diseases [2,3,4]. In the traditional growing method, lettuces stay in contact with the soil throughout their development. The humidity associated with organic fertilizers and water irrigation can provide ideal conditions for the contamination of these food products [4,5,6]. Mishandling of the vegetables during processing can turn these kinds of foods into vehicles of pathogenic bacteria [2,6]
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