It ain’t happening at retail: Cut cantaloupe needs to be stored at 4C to control Listeria growth

Cantaloupes, marketed as “Rocky Ford,” were implicated in the U.S. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. Listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons.

fresh-cut.cantaloupeThe growth of L. monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupe cultivars during refrigerated storage was evaluated. Fresh-cut cubes (16.4 cm3) from field-grown cantaloupes were each inoculated with 5 log10 CFU/mL of a multi-strain mixture of L. monocytogenes and stored at 4°C or 10°C. Inoculated fresh-cut cubes were also: (1) continuously stored at 4°C for 3 days; (2) temperature-abused (TA: 25°C for 4 h) on day 0; or (3) stored at 4°C for 24 h, exposed to TA on day 1, and subsequently stored at 4°C until day 3. L. monocytogenes populations on fresh-cut melons continuously stored at 4°C or 10°C were enumerated on selected days for up to 15 days and after each TA event. Brix values for each cantaloupe variety were determined. L. monocytogenes populations on fresh-cut cantaloupe cubes stored at 4°C increased by 1.0 and 3.0 log10 CFU/cube by day 7 and 15, respectively, whereas those stored at 10°C increased by 3.0 log10 CFU/cube by day 7.

Populations of L. monocytogenes on fresh-cut cantaloupes stored at 10°C were significantly (p < 0.05) greater than those stored at 4°C during the study. L. monocytogenes showed similar growth on fresh-cut “Athena” and “Rocky Ford” cubes, even though “Athena” cubes had significantly higher Brix values than the “Rocky Ford” fruit.

L. monocytogenes populations on fresh-cut cantaloupes exposed to TA on day 1 and then refrigerated were significantly greater (0.74 log10 CFU) than those stored continuously at 4°C for 3 days. Storage at 10°C or exposure to TA events promoted growth of L. monocytogenes on fresh-cut cantaloupe during refrigerated storage.

Survival and growth of Listeria monocytogenes on fresh-cut “Athena” and “Rocky Ford” cantaloupes during storage at 4°C and 10°C

Nyarko Esmond, Kniel Kalmia E., Reynnells Russell, East Cheryl, Handy Eric T., Luo Yaguang, Millner Patricia D., and Sharma Manan. Foodborne Pathogens and Disease. August 2016, ahead of print. doi:10.1089/fpd.2016.2160.

http://online.liebertpub.com/doi/abs/10.1089/fpd.2016.2160

Cross-contamination: It’s a risk, that no wiping on a chefs’s apron will reduce

Although quantitative studies have revealed that cross-contamination during the washing stage of fresh produce occurs, the importance of cross-contamination in terms of public health relevance has rarely been assessed.

bbq.bse.cross.contaminationThe direct distribution of initially contaminated leafy vegetables to a multitude of servings by cutting and mixing also has not been addressed. The goal of this study was to assess the attribution of both contamination pathways to disease risk. We constructed a transparent and exploratory mathematical model that simulates the dispersion of contamination from a load of leafy greens during industrial washing. The risk of disease was subsequently calculated using a Beta-Poisson dose-response relation.

The results indicate that up to contamination loads of 106 CFU the direct contamination route is more important than the indirect route (i.e., cross-contamination) in terms of number of illnesses. We highlight that the relevance of cross-contamination decreases with more diffuse and uniform contamination, and we infer that prevention of contamination in the field is the most important risk management strategy and that disinfection of washing water can be an additional intervention to tackle potentially high (>106 CFU) point contamination levels.

Public health relevance of cross-contamination in the fresh-cut vegetable industry

Journal of Food Protection, January 2016, No. 1, pp. 4-178, pp. 30-36(7) DOI: http://dx.doi.org/10.4315/0362-028X.JFP-15-272

Jurgen Chardon, Arno Swart, Eric Evers, Eelco Franz

http://www.ingentaconnect.com/content/iafp/jfp/2016/00000079/00000001/art00004

Go to grocery, plenty of abuse: Pathogens on fresh-cut cantaloupe

Effective cold chain management is a critical component of food safety practice.

fresh-cut.cantaloupeIn this study, we examined the impact of commonly encountered temperature abuse scenarios on the proliferation of Salmonella enterica and Listeria monocytogenes on fresh-cut cantaloupe.

Inoculated fresh-cut cantaloupe cubes were subjected to various temperature abuse conditions, and the growth of S. enterica and L. monocytogenes was determined.

During 1 week of storage, Salmonella cell counts on fresh-cut cantaloupe increased by –0.26, 1.39, and 2.23 log units at 4°C (control), 8°C, and 12°C (chronic temperature abuse), respectively, whereas that of L. monocytogenes increased by 0.75, 2.86, and 4.17 log units. Under intermittent temperature abuse conditions, where storage temperature fluctuated twice daily to room temperature for 30 min, Salmonella cell count increased by 2.18 log units, whereas that of L. monocytogenes increased by 1.86 log units. In contrast, terminal acute temperature abuses for 2 to 4 h resulted in upwards to 0.6 log unit for Salmonella, whereas the effect on L. monocytogenes was less significant compared with L. monocytogenes on cut cantaloupe stored at 4°C. Significant deterioration of produce visual quality and tissue integrity, as reflected by electrolyte leakage, was also observed under various temperature abuse conditions.

 Growth of Salmonella enterica and Listeria monocytogenes on fresh-cut cantaloupe under different temperature abuse scenarios

Journal of Food Protection®, Number 6, June 2015, pp. 1064-1243, pp. 1125-1131(7), DOI: http://dx.doi.org/10.4315/0362-028X.JFP-14-468

Huang, Jingwei; Luo, Yaguang; Nou, Xiangwu

http://www.ingentaconnect.com/content/iafp/jfp/2015/00000078/00000006/art00009

Listeria monocytogenes transfer during mechanical dicing of celery and growth during subsequent storage

The transfer of Listeria monocytogenes to previously uncontaminated product during mechanical dicing of celery and its growth during storage at various temperatures were evaluated. In each of three trials, 275 g of retail celery stalks was immersed in an aqueous five-strain L. monocytogenes cocktail to obtain an average of 5.6 log CFU/g and then was diced using a celery.fresh.cuthand-operated dicer, followed by sequential dicing of 15 identical 250-g batches of uninoculated celery using the same dicer. Each batch of diced celery was examined for numbers of Listeria initially and after 3 and 7 days of storage at 4, 7, and 10°C. Additionally, the percentage by weight of inoculated product transferred to each of 15 batches of uninoculated celery was determined using inoculated red stems of Swiss chard as a surrogate. Listeria transfer to diced celery was also assessed after removing the Swiss chard. L. monocytogenes transferred from the initial batch of inoculated celery to all 15 batches of uninoculated celery during dicing, with populations decreasing from 5.2 to 2.0 log CFU/g on the day of processing. At 10°C, Listeria reached an average population of 3.4 log CFU/g in all batches of uninoculated celery. Fewer batches of celery showed significant growth during storage at 4 and 7°C (P < 0.05). Swiss chard pieces were recovered from all 15 batches of celery, with similar amounts seen in batches 2 to 15 (P > 0.05). L. monocytogenes was also recovered from each batch of uninoculated celery after the removal of Swiss chard, with populations decreasing from 4.7 to 1.7 log CFU/g. Storing the diced celery at 10°C yielded a L. monocytogenes generation time of 0.87 days, with no significant growth observed during storage at 4 or 7°C. Consequently, mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery.

Journal of Food Protection®, Number 5, May 2014, pp. 696-863 , pp. 765-771(7)

Kaminski, Chelsea N.1; Davidson, Gordon R.2; Ryser, Elliot T.3

Texas fresh-cut plant shut after links to 5 listeria deaths in celery

Sometime in Jan. 2010, someone in Texas got really sick with listeria.

By mid-May, 2010, five were sick and two were dead – all from the same strain of listeria. By Oct. 20, 2010, five were sick and five had died from the same strain of listeria. Most of the listeriosis patients were elderly with serious underlying health problems, and many were hospitalized before and during the onset of their infection.

Health types said six of the 10 cases were conclusively linked to chopped celery sold by Sangar Fresh Cut Produce of San Antonio, so yesterday, the Texas Department of State Health Services ordered Sangar to stop processing food and recall all products shipped from the plant since January. The order was issued after laboratory tests of chopped celery from the plant indicated the presence of Listeria monocytogenes.

Sangar President Kenneth Sanquist Jr. took issue with the state, adding in a statement,

“The state’s claim that some of our produce now fails to meet health standards directly contradicts independent testing that was conducted on the same products. This independent testing shows our produce to be absolutely safe, and we are aggressively fighting the state’s erroneous findings.”

DSHS inspectors say that in the Sanger plant, they found a condensation leak above a food product area, soil on a preparation table and hand washing issues.

The recalled products – primarily cut fresh produce in sealed packages – were distributed to restaurants and institutional entities, such as hospitals and schools, and are not believed to be sold in grocery stores.

For a glimpse of the Sanger plant, see the video below from Aug. 13, 2010, when Sanquist told KENS5 TV in San Antonio there should be tougher standards in the fresh-cut industry, adding,

"All we’re saying is everyone should have that standard. There is an entire process that we have to follow on a daily basis, if you miss a step or two steps or try to take a short cut…children could get very sick."

Sanquist said many businesses only require their produce company have a recall program in place and that’s simply not enough prevention.