Insights in agricultural practices and management systems linked to microbiological contamination of lettuce in conventional production systems in Southern Brazil

Abstract

Background. Three conventional lettuce farms were evaluated in Southern Brazil using a standardized self-assessment questionnaire with 69 indicators and a microbiological sampling plan in order to assess the status of current agricultural practices and management systems. The use of both tools aimed to identify the foremost contamination sources and control measures during the crop production. A total of 128 samples were taken (manure, soil, water, workers’ hands and equipment, lettuce seedlings and lettuce heads) in four visits during the growth cycle of lettuces. Samples were analysed for hygiene indicators (E. coli) and presence of pathogens (Salmonella spp. and E. coli O157). Result.s Microbiological results indicated that E. coli counts were very low in all analysed samples and no pathogens were detected. These results could be explained partially because all farms had toilets near to the fields, they did not raise animals near the crops, fields were located in areas where flooding was not possible, they used organic fertilizers adequately composted, and irrigation water demonstrated good microbiological quality. The microbial results for manure and soil indicated that the composting time was of utmost importance to maintain minimal contamination levels for the duration of the cultivation period, as long as the quality of irrigation water was very important to prevent further contamination of the crop. On the other hand, the self-assessment questionnaire identified a moderate to high risk level concerning microbiological contamination in all evaluated farms, because they had no formal good agricultural practices implemented, technical support, water control, inspections, food safety registers or sampling plan for microbiological or chemical analyses. Conclusion. These different results are important in order to provide information about the actual status of contamination (microbial sampling plan) and possible food safety problems in the future based on the results given by the questionnaire. Furthermore, the results of this study also highlighted the necessity to provide more safety during the fresh produce cultivation, being formal good agricultural practices implementation an important start to the fresh produce farms in Brazil, as well as to adopt a higher level of control activities in order to achieve lower risk levels.