Ultraviolet-C light inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on organic fruit surfaces

Adhikari, Achyut; Roopesh, M.S.; Killinger, Karen; Sablani, Shyam S.

doi:10.1016/j.ijfoodmicro.2015.06.018

Cited by 113 publications

(49 citation statements)

References 34 publications

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“…Although the listeriosis outbreak evaluated here is the first to be attributed to whole caramel apples, studies have shown that L. monocytogenes is capable of both surviving and growing on raw fruits such as whole and cut melons (13,14,20,23,27), melon pulp (26), cut pears (1,11,23), and whole and cut berries (1,23). This pathogen also can proliferate on fresh-cut apple slices when contamination occurs after processing procedures, such as peeling and cutting (2, 4, 12).…”

Section: Discussionmentioning

confidence: 96%

Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples

Salazar

Carstens

Bathija

et al. 2016

Journal of Food Protection

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An outbreak of listeriosis in late 2014 and early 2015 associated with caramel apples led to questions about how this product became a vector for Listeria monocytogenes. This investigation aimed to determine information about the survival and growth of L. monocytogenes in both fresh apples and caramel apples, specifically examining the effects of site and level of inoculation, inoculum drying conditions, and storage temperature. At a high inoculation level (7 log CFU per apple), L. monocytogenes inoculated at the stem end proliferated on Gala caramel apples at both 5 and 25°C and on Granny Smith caramel apples at 25°C by as much as 3 to 5 log CFU per apple. Fresh apples and caramel apples inoculated at the equatorial surface supported survival but not growth of the pathogen. Growth rates (μmax) for apples inoculated at the stem end, as determined using the Baranyi and Roberts growth model, were 1.64 ± 0.27 and 1.38 ± 0.20 log CFU per apple per day for Gala and Granny Smith caramel apples, respectively, stored at 25°C. At a low inoculation level (3 log CFU per apple), L. monocytogenes inoculated at the stem end and the equatorial surface survived but did not grow on fresh Gala and Granny Smith apples stored at 25°C for 49 days; however, on caramel apples inoculated at the stem end, L. monocytogenes had significant growth under the same conditions. Although certain conditions did not support growth, the pathogen was always detectable by enrichment culture. The inoculation procedure had a significant effect on results; when the inoculum was allowed to dry for 24 h at 5°C, growth was significantly slowed compared with inoculum allowed to dry for 2 h at 25°C. Variation in stick materials did affect L. monocytogenes survival, but these differences were diminished once sticks were placed into caramel apples.

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Section: Discussionmentioning

confidence: 96%

Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples

Salazar

Carstens

Bathija

et al. 2016

Journal of Food Protection

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“…Before activation, bacterial strains were stored at −80°C. Frozen cultures were activated in three successive passes by following the procedure described by (Adhikari et al, ). The final inoculum size of the generic E. coli was 10 8 CFU/mL.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of ultraviolet (UV‐C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity

Adhikari

Parraga

Chhetri

et al. 2020

Food Science & Nutrition

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Produce growers using surface or well water to irrigate their crops may require an appropriate water treatment system in place to meet the water quality standard imposed by FSMA Produce Safety Rule. This study evaluated the potential of using ultraviolet (UV‐C) treatment in reducing the microbial population in agricultural water. Waters with turbidity levels ranging from 10.93 to 23.32 Nephelometric Turbidity Units (NTU) were prepared by mixing pond water and well water. The waters were inoculated with a cocktail of generic Escherichia coli (ATCC 23716, 25922, and 11775) and then treated with UV‐C light (20–60 mJ/cm2). All tested doses of the UV‐C treatment reduced the E. coli levels significantly (p < .05) in the water samples with the turbidity levels up to 23.32 NTU. The decrease in the turbidity from 23.32 to 10.93 NTU increased the level of reduction by more than 2.15 log most probable number (MPN)/100 ml). UV‐C treatment effectively reduces microbial load in agriculture water; however, turbidity of water may significantly affect the disinfection efficacy. The study also demonstrated that sprinkler system resulted in a higher level of contamination of cantaloupes compared with drip irrigation. The results indicated that UV‐C treatment could be a promising strategy in reducing the produce safety risks associated with irrigation water.

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“…These strains are among the few wellcharacterized surrogates for use in field trials (Harris et al, 2012). Frozen cultures were activated in three successive passes by following the procedure described by Adhikari, Syamaladevi, Killinger, and Sablani (2015). The final inoculum size was 10 9 CFU/ml.…”

Section: Watermelon Disc Preparation and Inoculation With Generic Ementioning

confidence: 99%

Effect of surrounding vegetation on microbial survival or die‐off on watermelon surface in an agriculture setting

Chhetri

Fontenot

Strahan

et al. 2018

Journal of Food Safety

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Preharvest contamination of produce with food borne pathogens has been a major food safety issue. In this study, we investigated the effect of surrounding vegetation on the survival of natural and inoculated generic Escherichia coli on watermelon rinds in an agricultural field setting. There was no significant difference (p > .05) on the populations of natural generic E. coli (1–1.46 log Most Probable Number (MPN)/sample) and coliforms (<3.99 log CFU/cm2) on watermelons harvested from low, medium, and high levels of vegetation. However, the survival rate of generic E. coli inoculated on watermelon rind discs was variable with the level of vegetation. A significant reduction in generic E. coli count was observed within 12 hr at all vegetation levels. After 108 hr, discs placed at low vegetation level had a highest die‐off reduction (3 log Colony Forming Units (CFU)/cm2) compared to medium and high vegetation levels. Practical applications To ensure preharvest produce safety, the Food Safety Modernization Act (FSMA) produce safety rule has suggested a time interval between last irrigation and harvest for potentially contaminating microorganisms to die‐off. However, a knowledge gap exists regarding the influence of surrounding vegetation on microbial die‐off rates on produce in the agricultural field. The findings of this study emphasize the importance of considering the surrounding vegetation while making decisions for developing preharvest risk management strategies based on microbial die‐off rate calculations.

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Ultraviolet-C light inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on organic fruit surfaces

Cited by 113 publications

References 34 publications

Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples

Fate of Listeria monocytogenes in Fresh Apples and Caramel Apples

Evaluation of ultraviolet (UV‐C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity

Effect of surrounding vegetation on microbial survival or die‐off on watermelon surface in an agriculture setting

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