MALDONADE, I. R.

SANJINEZ-ARGANDOÑA, E. J.

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V International Conference on Environmental, Industrial and Applied Microbiology – BioMicroWorld 2013 Madrid (Spain), 2-4 October 2013 195  Effect of natural detergent solutions against E. coli growth in fresh-cut lettuce I. R. Maldonade1,2 and E. J. Sanjinez-Argandona3 1Embrapa Vegetables, CNPH, Department of Food Science & Technology, Rodovia BR 060 Km 09, Brasilia-DF, Brazil 2Visiting Research Fellow, Building Engineering, London South Bank University, London, United Kingdom 3Federal University of Grande Dourados (UFGD), Faculty of Engineering, Dourados-MS, Brazil  Over the past few years there has been an increasing consumption of fruits and vegetables that have beenassociated with healthy eating. However, contamination in ready-to-eat salads by microorganisms mighty be a potential threat to consumers because they are not washed and disinfected before consumed. Besides, recent outbreaks of E. coli in Germany, in May 2011, have raised the attention of European Community to the risk of microbial contamination in fresh-cut produce and the need to encourage safer procedures of sanitization during their processing in the agro-industry. In this context, the aim of this work was to propose the use of natural detergent with disinfection action to against growth of bacteria during pre-washing step. Experiments were carried out by inoculating Escherichia coli (106 CFU) in100g of fresh-cut lettuce and incubated at 25 °C. After 2h, the samples were immersed in two different detergent solutions (DS) containing Tween 20, citric acid and lime oil (A: 1.0% lime oil and 0.5% of citric acid; B: 1.0% lime oil and 0.3% of citricacid) during 1, 5 and 10 minutes. The control treatment was washed only with water. The samples (treated lettuce) were withdrawn and evaluated to determine the reduction of E.coli colonies formed, after a sequential ofdilutions (1:10) of the samples flasks, from which 100 _L were spread onto the MacConkey agar plates and incubated at 37 °C for 24 h [1]. The microbial plate count was expressed as the logarithm of colony-forming units per 25 gram of fresh weight of lettuce (log CFU/25g FW). The results showed that survival of microorganisms of minimally processed lettuce immersed in solution A and B decreased significantly with increasing time of immersion, while washing with water (control) presented only a reduction at first minute (from 7.8 to 4.34 log CFU/25g), but kept growing after 1minute of treatment. Ten minutes of sanitizing solution contact significantly reduced bacteria populations for both detergent solutions tested by 7.80 to 1.60 log CFU/25g FW (solution A) and 7.80 to 3.25 log CFU/25g FW (solution B). There has been no significant reduction of colonies formed after 1 minute of treatment with solution B: 3.56 log CFU/25g at 1 minute and 3.51 log CFU/25g at 5 minutes. Detergent solution A was the most effective on reducing E. coli, although the best organoleptic results were shown by solution B. The findings suggest that washing fresh produce for 1 minute in a solution containing citric acid at low concentration improves the shelf life of lettuce by decreasing the metabolism of the vegetable. Thus, lime oil and citric acid formulated as a detergent solution with Tween showed a synergistic action against E. coli growth [1] and it can be considered to be used as a natural alternative of conventional sanitizing agents in the food industry.  Keywords: pathogens; contamination; citrus oil; citric acid; ready-to-eat vegetables; sanitazer agents  References [1] MALDONADE, I. R.; SANJINEZ-ARGANDONA, E. J. Inhibitory synergism effect of citric acid, citrus oil and nisin on growth of Escherichia coli. In: A Mendez-Vilas. (Org.). MICROBES IN APPLIED RESEARCH: Current Advances and Challenges. 1ed.Malaga, Spain: World Scientific, 2012, v. 02, p. 551-555. [2] RUIZ-CRUZ, S.; ACEDO-FELIX, E.; DIAZ-CINCO, M.; ISLAS-OSUNA, M. A.; GONZALEZ-AGUILA, G. A. Efficacy of sanitizers in reducing Escherichia coli, Salmonella spp. and Listeria monocytogenes populations on fresh-cut carrots. Food Control, 18: 1383-1390, 2007. 

Effect of natural detergent solutions against E. coli growth in fresh-cut lettuce.

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Effect of natural detergent solutions against E. coli growth in fresh-cut lettuce.

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