Modelling growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to commercial process conditions: Chlorine washing and modified atmosphere packaging

Posada-Izquierdo, Guiomar Denisse; Pérez‐Rodríguez, Fernando; López‐Gálvez, Francisco; Allende, Ana; Selma, María V.; Gil, María I.; Zurera, G.

doi:10.1016/j.fm.2012.08.010

Cited by 41 publications

(28 citation statements)

References 45 publications

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“…This is in agreement with literature (Erickson, 2012) and with the fact that, particularly in Europe, the use of sanitizers is mainly recommended to keep the wash water clean rather than to decontaminate the lettuce (Baert et al, 2009;Velazquez et al, 2009;Zhang et al, 2009). Our results indicated that subsequent storage of treated lettuce (PAA + LA or NaClO) under modified atmosphere at 7°C revealed no significant influence of the pathogen level on the lettuce, which was is in accordance with the work of Posada-Izquierdo (Posada-Izquierdo et al, 2012) nor regarding the attachment/internalization of the bacteria. Our study indicates that various storage conditions (modified atmosphere or NAA, in the dark or exposure to light) of either water washed or sanitizer treated (PAA + LA or NaClO) fresh-cut Iceberg lettuce had no substantial influence on the survival, internalization and attachment of Salmonella and E. coli O157 cells on the lettuce leaves (surface or cut-edge).…”

Section: Discussionsupporting

confidence: 88%

“…By applying MAP, the respiration rate of lettuce is reduced due to the low O 2 percentage in the package which retards browning and inhibits the outgrowth of aerobic spoilage bacteria (Posada-Izquierdo et al, 2012). It was already shown that this may induce acid resistance of E. coli O157 on lettuce but only when stored at growth permissive temperatures (≥15°C) (Chua et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella

Linden

Avalos-Llano

Eriksson

et al. 2016

International Journal of Food Microbiology

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The influence of a selection of minimal processing techniques (sanitizing wash prior to packaging, modified atmosphere, storage conditions under light or in the dark) was investigated in relation to the survival of, attachment to and internalization of enteric pathogens in fresh produce. Cut Iceberg lettuce was chosen as a model for fresh produce, Escherichia coli O157:H7 (E. coli O157) and Salmonella enterica were chosen as pathogen models. Care was taken to simulate industrial post-harvest processing. A total of 50 ± 0.1 g of fresh-cut Iceberg lettuce was packed in bags under near ambient atmospheric air with approximately 21% O 2 (NAA) conditions or equilibrium modified atmosphere with 3% O 2 (EMAP). Two lettuce pieces inoculated with E. coli O157 BRMSID 188 or Salmonella Typhimurium labeled with green fluorescent protein (GFP) were added to each package. The bags with cut lettuce were stored under either dark or light conditions for 2 days at 7°C. The pathogens' capacity to attach to the lettuce surface and cut edge was evaluated 2 days after inoculation using conventional plating technique and the internalization of the bacteria was investigated and quantified using confocal microscopy. The effect of a sanitizing wash step (40 mg/L NaClO or 40 mg/L peracetic acid + 1143 mg/L lactic acid) of the cut lettuce prior to packaging was evaluated as well. Our results indicate that both pathogens behaved similarly under the investigated conditions. Pathogen growth was not observed, nor was there any substantial influence of the investigated atmospheric conditions or light/dark storage conditions on their attachment/internalization. The pathogens attached to and internalized via cut edges and wounds, from which they were able to penetrate into the parenchyma. Internalization through the stomata into the parenchyma was not observed, although some bacteria were found in the substomatal cavity. Washing the cut edges with sanitizing agents to reduce enteric pathogen numbers was not more effective than a rinse with precooled tap water prior to packaging. Our results confirm that cut surfaces are the main risk for postharvest attachment and internalization of E. coli O157 and Salmonella during minimal processing and that storage and packaging conditions have no important effect.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella

Linden

Avalos-Llano

Eriksson

et al. 2016

International Journal of Food Microbiology

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“…The application of chlorine at 50 ppm of chlorine in iceberg lettuce reduced the E. coli O157:H7 populations by 3.79 log CFU/mL after 90 s of treatment (Davidson et al 2013 ). Similarly, Posada-Izquierdo et al ( 2013 ) reported that chlorination treatment followed by a rinsing step in tap water reduced the initial level of E. coli O157:H7 by 1.23 log CFU/g. The populations of Shigellasonnei inoculated onto whole parsley leaves were reduced by more than 7 log CFU/g after treatment for 5 min with 250 ppm of free chlorine ( Van Duyn and Pivonka 2000 ).…”

Section: Chlorinementioning

confidence: 92%

Washing, Peeling and Cutting of Fresh-Cut Fruits and Vegetables

Tapia

Gutiérrez-Pacheco

Vázquez-Armenta

et al. 2014

Food Engineering Series

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“…Temperature is also a key factor in fresh-cut processing plants. Many research papers described the relevance of low temperature as a strategy to avoid/reduce bacterial growth of foodborne pathogens in leafy greens (Abadias et al, 2012;Oliveira et al, 2010a;Posada-Izquierdo et al, 2013;Sant'Ana et al, 2012). In general, it is reported that the growth of Salmonella in leafy greens can be controlled by ensuring that these products are stored at a temperature below 7ºC.…”

Section: Environmental Factorsmentioning

confidence: 99%

Scientific Opinion on the risk posed by pathogens in food of non‐animal origin. Part 2 (Salmonella and Norovirus in leafy greens eaten raw as salads)

Publication¹

2014

EFS2

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Leafy greens eaten raw as salads are minimally processed and widely consumed foods. Risk factors for leafy greens contamination by Salmonella spp. and Norovirus were considered in the context of the whole food chain including agricultural production and processing. Available estimates of the prevalence of these pathogens (together with the use of Escherichia coli as an indicator organism) in leafy greens were evaluated. Specific mitigation options relating to contamination of leafy greens were considered and qualitatively assessed. It was concluded that each farm environment represents a unique combination of numerous characteristics that can influence occurrence and persistence of pathogens in leafy greens production. Appropriate implementation of food safety management systems, including Good Agricultural Practices (GAP), Good Hygiene Practices (GHP) and Good Manufacturing Practices (GMP), should be primary objectives of leafy green producers. The relevance of microbiological criteria applicable to production, processing and at retail/catering were considered. The current legal framework does not include microbiological criteria applicable at primary production which will validate and verify GAP and GHP. It is proposed to define a criterion at primary production of leafy greens which is designated as Hygiene Criterion, and E. coli was identified as suitable for this purpose. A Process Hygiene Criterion for E. coli in leafy green packaging plants or fresh cutting plants was considered and will also give an indication of the degree to which GAP, GHP, GMP or HACCP programs have been implemented. A Food Safety Criterion for Salmonella in leafy greens could be used as a tool to communicate to producers and processors that Salmonella should not be present in the product. Studies on the prevalence and infectivity of Norovirus are limited, and quantitative data on viral load are scarce making establishment of microbiological criteria for Norovirus on leafy greens difficult.

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Modelling growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to commercial process conditions: Chlorine washing and modified atmosphere packaging

Cited by 41 publications

References 45 publications

Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella

Minimal processing of iceberg lettuce has no substantial influence on the survival, attachment and internalization of E. coli O157 and Salmonella

Washing, Peeling and Cutting of Fresh-Cut Fruits and Vegetables

Scientific Opinion on the risk posed by pathogens in food of non‐animal origin. Part 2 (Salmonella and Norovirus in leafy greens eaten raw as salads)

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