Food Protection Trends - November/December 2023 - 473

last 10 years, postchill tanks, located after the primary chiller,
have become a popular step for the application of antimicrobial
interventions. These tanks resemble a traditional chiller
but with lower volume ranges (400-600 gal [1.5-2.3 kl],
compared with 20,000-50,000 gal [75.7-189.3 kl]), resulting
in shorter product residence times (20). Typical residence
times in chill tanks range from 1.5 to 2 h, whereas contact
time in postchill tanks can be less than 30 s (8). Therefore,
higher concentrations of antimicrobials can be used in
postchill tanks with fewer safety or quality concerns (8). In
addition, postchill tanks have lower levels of organic matter
buildup, which may increase the efficacy of antimicrobials
(8). Currently approved antimicrobials for postchill tanks,
including ozone-based applications, are listed in USDA-FSIS
Directive 7120.1 (29).
Gaseous and aqueous ozone treatments have been
proposed as effective antimicrobials with fewer quality and
environmental concerns than other chemicals (3). Ozone
is highly reactive and has strong oxidizing power (3), thus
disrupting sulfhydryl groups, polysaccharides, unsaturated
fatty acids, and nucleotides in bacterial cell membranes, cell
envelopes, cytoplasm, and spore coats, as well as in virus
capsids (3, 17). In addition, ozone readily decomposes into
hydroxyl, hydroperoxyl, and superoxide radicals, which
eventually turn into oxygen, thus minimizing residues on
the surface of the product (17, 18). Current aqueous ozone
systems generate ozone gas from ambient air and inject the
ozone into water streams (10). Because of its reactivity and
rapid decomposition, ozone cannot be accumulated, so it is
generated continuously as needed, which means that there
are no chemical storage concerns (3).
The use of ozone and ozonated water for food safety
applications in the food industry has already been
reviewed (3, 5, 17, 23, 24). Factors that influence
application efficacy include treatment factors, such as
physical state, exposure time, and ozone concentration;
bacterial factors, such as cell wall composition and
physiological state; and matrix or environmental factors,
such as temperature, pH, and presence of ozoneconsuming
compounds (3, 17, 23). For chicken parts
specifically, fat content, presence of skin or bones,
ozone dose (combination of exposure time and ozone
concentration), and bacterial attachment appear to be
important (5). However, few studies have focused on
ozonated water as an antimicrobial intervention for
poultry parts or compared the effect of each of these
factors on the efficacy of ozonated water (15, 19, 30).
This is an important knowledge gap that affects the
implementation of ozone-based treatments in the
poultry industry. Therefore, the objective of this study
was to determine the efficacy of ozonated water to
decontaminate Salmonella and background microbiota on
raw chicken wing sections under simulated product and
process conditions.
MATERIALS AND METHODS
Sample preparation
Fresh raw chicken wing sections in the form of partymix
trays, containing both drums or drumettes and flats
or wingettes, were purchased at a local retailer in Lincoln,
Nebraska. A single commercial brand was consistently
procured for all experiments. Preliminary studies (data
not shown) confirmed aerobic plate count (APC) < 100
CFU/ml rinsate and nondetectable Salmonella in fresh
chicken wings. Samples were maintained at 4°C in the
laboratory and used within 72 h of the sell-by date to ensure
complete product thawing before artificial inoculation with
Salmonella, as well as sufficient and consistent growth of
indigenous microflora to estimate APC populations. Three
chicken wing sections from each replicate were reserved to
enumerate initial APC values.
Inoculum preparation and sample inoculation
Five Salmonella serovars isolated from chicken products
were provided by the University of Nebraska-Lincoln Food
Processing Center's Food Microbiology Service Laboratory.
Salmonella serovars Braenderup (n = 1), Enteritidis
(n = 2), Hadar (n = 1), and Typhimurium (n = 1) were
stored in tryptic soy broth (TSB; Remel, Lenexa, KS) with
20% glycerol at −80°C. For the experiment, isolates were
removed from frozen storage, streaked onto individual
plates of xylose lysine deoxycholate agar (XLD; BD, Franklin
Lakes, NJ), and incubated at 37°C for 18-24 h. One
isolated colony of each strain was inoculated into 10 ml of
TSB and incubated at 37°C for 18-24 h. For each culture, 1
ml of suspension was then transferred to a bottle of 200 ml
of TSB. The five bottles were incubated at 37°C for 18-24 h.
After incubation, the five cultures were combined in a sterile
stainless steel container (4.5 qt [4.25 liters]; Syscoware,
Houston, TX) to yield 1 liter of working inoculation
cocktail (25). Chicken wing sections were immersed in the
bacterial suspension for 30 s and then placed on stainless
steel racks in a biosafety cabinet for 20 min to allow for bacterial
attachment. Afterward, the wings were stored at 4°C
for 18-24 h before the experiments were conducted. Three
chicken wing sections from each replicate were reserved to
enumerate the initial concentration of Salmonella.
Ozonated water treatment of chicken wing sections
Ozonated water was generated using a prototype
TetraClean aqueous ozone system (TetraClean, Omaha,
NE). The system generates ozone from oxygen gas in
the air. The ozone gas is then bubbled into tap water (ca.
20°C). The ozonated water is recirculated and infused
with additional ozone gas to increase the gas levels until
the desired concentration is achieved. The nominal
ozone concentration range of the equipment is 0.0-20.0
ppm; however, the ozone concentration in water is most
stable in the 0.0- to 10.0-ppm range. Ozonated water flow
November/December Food Protection Trends 473
Food Protection Trends - November/December 2023

Table of Contents for the Digital Edition of Food Protection Trends - November/December 2023
