Growth potential of Listeria monocytogenes in six different RTE fruit products: impact of food matrix, storage temperature and shelf life

Ziegler, Mathias; Rüegg, Simon R.; Stephan, Roger; Guldimann, Claudia

doi:10.4081/ijfs.2018.7581

Cited by 16 publications

(15 citation statements)

References 27 publications

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“…Several factors influence host infection rates, notably temperature. In the present work, samples of inoculated plant tissues were stored at 8 °C, a temperature at the higher end of the spectrum of domestic refrigerator temperatures ( James et al., 2017 , James et al., 2008 , Ziegler et al., 2018 ) but at the lower end of growth permissive temperatures for Salmonella spp. ( D’aoust, 1993 , Matches and Liston, 1968 ) .…”

Section: Resultsmentioning

confidence: 99%

Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail

Wong

Delaquis

Goodridge

et al. 2020

Current Research in Food Science

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Salmonella enterica ( S. enterica ) is a causative agent of multiple outbreaks of foodborne illness associated with fresh produce, including pre-cut melon and leafy vegetables. Current industrial antimicrobial interventions have been shown to reduce microbial populations by <90%. Consequently, bacteriophages have been suggested as an alternative to chemical sanitizers. Seven S. enterica strains from four serovars (10 5 CFU/mL) were separately inoculated onto excised pieces of Romaine lettuce leaf and cantaloupe flesh treated with a five-strain bacteriophage cocktail 24 h before S. enterica inoculation. S. enterica , total aerobic populations and water activity were measured immediately after inoculation and after 1 and 2 days of incubation at 8 °C. The efficacy of the bacteriophage cocktail varied between strains. Populations of S. enterica Enteritidis strain S3, S. Javiana S203, S. Javiana S200 were reduced by > 3 log CFU/g and S. Newport S2 by 1 log CFU/g on both lettuce and cantaloupe tissues at all sampling times. In contrast, populations of strains S. Thompson S193 and S194 were reduced by 2 log CFU/g on day 0 on lettuce, but were not significantly different (P > 0.05) from the controls thereafter, S. Newport S195 populations were reduced on lettuce by 1 log CFU/g on day 0 and no reductions were found on cantaloupe tissue. Both aerobic populations and water activity were higher on cantaloupe than on lettuce. The water activity of lettuce decreased significantly (P < 0.05) from 0.845 ± 0.027 on day 0–0.494 ± 0.022 on day 1, but that of cantaloupe remained between 0.977 and 0.993 from day 0–2. The results of this study showed that bacteriophages can reduce S. enterica populations on lettuce and cantaloupe tissues but that the magnitude of the effect was strain-dependent.

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Section: Resultsmentioning

confidence: 99%

Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail

Wong

Delaquis

Goodridge

et al. 2020

Current Research in Food Science

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“…Despite the possible underestimation of growth potential, assessing growth potentials at high inoculation densities (i.e., 10 5 cfu g −1 ) in RTE food remains popular [15]. According to the guidance produced by the European Union Reference laboratory (EURL), if any food product shows growth potential (δ) greater than 0.50 log 10 cfu g −1 , it is regarded as being permissive to the growth of L. monocytogenes [16,17]. Consequently, changes in the inoculation density or other environmental factors may affect the outcome of challenge studies with the potential to underestimate growth.…”

Section: Introductionmentioning

confidence: 99%

Growth Potential of Listeria monocytogenes on Refrigerated Spinach and Rocket Leaves in Modified Atmosphere Packaging

Culliney

Schmalenberger

2020

Foods

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Minimally processed ready-to-eat (RTE) vegetables are increasingly consumed for their health benefits. However, they also pose a risk of being ingested with food-borne pathogens. The present study investigated the ability of RTE spinach and rocket to support the growth of Listeria monocytogenes as previous studies provided contradicting evidence. Findings were compared to growth on iceberg lettuce that has repeatedly been shown to support growth. Products were inoculated with a three-strain mix of L. monocytogenes at 10 and 100 cfu g−1 and stored in modified atmosphere (4 kPa O2, 8 kPa CO2) at 8 °C over 7–9 days. Spinach demonstrated the highest growth potential rate of 2 to 3 log10 cfu g−1 over a 9-day period with only marginal deterioration in its visual appearance. Growth potential on rocket was around 2 log10 cfu g−1 over 9 days with considerable deterioration in visual appearance. Growth potential of iceberg lettuce was similar to that of rocket over a 7-day period. Growth curves fitted closely to a linear growth model, indicating none to limited restrictions of growth over the duration of storage. The high growth potentials of L. monocytogenes on spinach alongside the limited visual deterioration highlight the potential risks of consuming this raw RTE food product when contaminated.

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“…Researchers (26,50) have noted that incubation temperature and nutrient availability are major factors affecting pathogen growth and thus food safety risks associated with fresh-cut produce. The concept of timetemperature control for fresh produce, particularly freshcut fruits and vegetables, has historically been relied upon to maintain quality and extend the shelf life of whole produce and fresh-cut products (31,44).…”

Section: Resultsmentioning

confidence: 99%

Holding Fresh-Cut Produce under Refrigeration May Not Prevent Pathogen Growth: Implications for Time-Temperature Control to Reduce Risk

Zhao¹,

Hanson²,

Ingham³

2021

FPT

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The U.S. Food and Drug Administration Food Code suggests that holding fresh-cut produce at < 5°C will limit growth of pathogenic microorganisms. Here, we determined whether cucumber, onion, pepper, mango, and tomato supported growth of Listeria monocytogenes (LM), Shiga toxin-producing Escherichia coli (STEC), and Salmonella enterica (SALM) at 5, 10, and 22°C.Produce was surface-pasteurized, diced, inoculated with single-pathogen cocktails, and incubated. Survivors were then enumerated with change in population (Δ-log CFU per gram) determined over time. Mango did not support pathogen growth at 5 or 10°C, but SALM and STEC exhibited significant (P < 0.05) growth on mango at 22°C (2.85 and 1.41 Δ-log CFU/g, respectively). At 5°C, significant (P < 0.05) growth was seen on cucumber inoculated with SALM and LM; onion and pepper inoculated with LM; and tomato inoculated with STEC. At 10°C, freshcut cucumber, onion, and pepper supported significant (P < 0.05) increases in SALM, STEC, and LM, along with SALM on tomato; Δ-log ranged from 3.37 (onion, LM) to 5.40 CFU/g (pepper, SALM). Growth of pathogens was not significantly different (P < 0.05) at 10 and 22°C for SALM or STEC inoculated onto onion, pepper, cucumber, or tomato. Results suggest that holding fresh-cut produce at or near refrigeration temperatures (5 or 10°C) may not control risk of pathogen growth.

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Growth potential of Listeria monocytogenes in six different RTE fruit products: impact of food matrix, storage temperature and shelf life

Cited by 16 publications

References 27 publications

Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail

Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail

Growth Potential of Listeria monocytogenes on Refrigerated Spinach and Rocket Leaves in Modified Atmosphere Packaging

Holding Fresh-Cut Produce under Refrigeration May Not Prevent Pathogen Growth: Implications for Time-Temperature Control to Reduce Risk

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