Food Protection Trends - September/October 2022 - 381

ples were treated statically in petri dishes, and the effect of a
turbulent flow regime, which is the novelty of the commercial
UV device used in the present study, was not considered.
The use of this particular UV device may explain the higher
inactivation rates found in our study. In another recent study,
the effectiveness of UV‐C radiation for reducing the microbial
population in agricultural water (turbidity of 10.93 to
23.32 NTU) was evaluated (1). Samples were inoculated
with E. coli (ATCC 23716, ATCC 25922, and ATCC 11775)
and treated with UV doses of 20 to 60 mJ/cm2
. In contrast to
our results, UV‐C treatment effectively reduced the microbial
load in agricultural water, but turbidity significantly affected
the disinfection efficacy. In that study, the UV chamber
of the UV-C light treatment equipment (PMD 150C1/4,
Aquionics, Slough, Charlotte, NC) was 0.2 m in diameter
but the flow rate and Reynolds number associated with the
treatments were not reported, so comparisons of results are
limited. Overall, the inactivation values reported in that study
were lower than those obtained in our investigation, even in
water samples with a lower turbidity level treated at a higher
UV dose. In our study, the liquid was pumped through the
UV treatment system in a thin film, using a turbulent flow
regime, which may explain the higher inactivation values and
the nonsignificant effect of turbidity.
The UV device evaluated in this study could be effectively
used for treatment of agricultural water, given the ease of
use and its low energy requirements. This device is one of
the most commonly used commercial UV machines for
the nonthermal processing of apple cider in the United
States (16). The most important innovation with this UV
treatment unit is that it senses the UV exposure every 20 ms
and automatically adjusts the flow rate to ensure appropriate
and consistent UV exposure. Although agricultural water is
extreme variable, this unit can accommodate for variations
that may be encountered. Some barriers that may hinder a
broad implementation of the technology in the open fields
are the required initial investment and access to an energy
source in the field.
REFERENCES
1. Adhikari, A., K. J. Parraga Estrada, V. S.
Chhetri, M. Janes, K. Fontenot, and J. C.
Beaulieu. 2020. Evaluation of ultraviolet
(UV‐C) light treatment for microbial
inactivation in agricultural waters with
different levels of turbidity. Food Sci. Nutr.
8:1237-1243.
2. Álvarez-Ordóñez, A., D. Leong, B. Hickey,
A. Beaufort, and K. Jordan. 2015. The
challenge of challenge testing to monitor
Listeria monocytogenes growth on ready-to-eat
foods in Europe by following the European
Commission (2014) Technical Guidance
document. Food Res. Int. 75:233-243.
3. Banach, J. L., and H. J. Van der Fels-Klerx.
2020. Microbiological reduction strategies
of irrigation water for fresh produce. J. Food
Prot. 83:1072-1087.
4. Callejón, R. M., M. I. Rodríguez-Naranjo,
C. Ubeda, R. Hornedo-Ortega, M. C. GarciaParrilla,
and A. M. Troncoso. 2015. Reported
foodborne outbreaks due to fresh produce
in the United States and European Union:
trends and causes. Foodborne Pathog. Dis.
12:32-38.
5. Dieter, C. A., M. A. Maupin, R. R. Caldwell,
M. A. Harris, T. I. Ivahnenko, J. K. Lovelace,
N. L. Barber, and K. S. Linsey. 2018. Estimated
use of water in the United States in
2015. Circular 1441. U.S. Geological Survey,
Reston, VA.
6. Farrell, C., F. Hassard, B. Jefferson, T. Leziart,
A. Nocker, and P. Jarvis. 2018. Turbidity
composition and the relationship with
microbial attachment and UV inactivation
efficacy. Sci. Total Environ. 624:638-647.
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at: https://www.globalgap.org/uk_en/
documents/. Accessed 16 March 2022.
8. Hanes, D. E., R. W. Worobo, A. Orlandi,
D. H. Burr, M. D. Miliotis, M. G. Robl,
J. W. Bier, M. J. Arrowood, J. J. Churey,
and G. J. Jackson. 2002. Inactivation of
Cryptosporidium parvum oocysts in fresh
apple cider by UV irradiation. Appl. Environ.
Microbiol. 68:4168-4172.
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CONCLUSIONS
The present study results indicate that UV radiation can
be an effective mitigation strategy for pond surface irrigation
water treatment. With a commercially available juice
processing unit that automatically adjusts the liquid flow
rate based on the fluid UV absorbance, E. coli and Salmonella
levels were reduced from approximately 8 to < 2 log CFU/
mL. This method is a promising technological alternative for
agricultural water treatment and is of particular relevance,
considering the numerous outbreaks linked to contaminated
produce and the increasingly limited supply of high-quality
water for agricultural use (12).
Further research is needed to confirm the efficacy of
the proposed treatment against parasites of public health
concern, such as Cryptosporidium and Giardia, and against
viruses, considering that ≥ 4-log removal and/or inactivation
is required for drinking water. The UV device evaluated in
this study was previously confirmed to be effective against
Cryptosporidium parvum in turbid and cloudy apple cider (8),
and a similar germicidal effect against this parasite is expected
in surface agricultural water.
ACKNOWLEDGMENTS
This work was supported by an Agriculture and Food
Research Initiative Foundational Program grant (201667017-24421,
program code A1331 Improving Food Safety)
to R. Ivanek from the U.S. Department of Agriculture
National Institute of Food and Agriculture (USDA-NIFA).
The work was also partially supported by the Center for
Produce Food Safety (CPS), (801 172 2018CP504) to R.
Ivanek and by the Specialty Crop Research Initiative program
from the USDA-NIFA (grant 2019-51181-30016). Any
opinions, findings, and conclusions expressed in this material
are those of the authors and do not necessarily reflect the
views of the USDA-NIFA or CPS.
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