Bacteria under
threat with new packaging device – study
Source of Article: http://www.foodproductiondaily.com/Product-Categories/Packaging-Materials/Bacteria-under-threat-with-new-packaging-device-study By Jane Byrne, 05-Mar-2009
Researchers claim to have discovered a
method to eliminate bacteria in packaged foods such as spinach and tomatoes,
a process that could reduce the number of food-borne outbreaks linked to the
produce.
The
findings have been published in the journal, LWT - Food Science and
Technology. The
device, according to researchers Kevin Keener and Paul Klockow,
consists of a set of high-voltage coils attached to a small transformer that
generates a room-temperature plasma field inside a package, ionizing the
gases inside. They
maintain that the process kills food contamination causing pathogens such as E.
coli and Salmonella. Demand
for natural According
to the 2007 US Department of Agriculture (USDA) Economic Research Service
statistics, fresh spinach reached a record consumption in 2005, up more than
12 times the amount consumed in 1970, while processed spinach consumption has
declined over the last few decades. The
authors of the study claim that this high demand puts pressure on producers
and processors to ensure that products are safe for consumption and still
retain nutritious and aesthetic qualities, so while minimal processing and
treatment is needed to ensure this there are many sources of contamination
that can affect produce before, during, and after harvest. Sanitation
methods Conventional
methods of sanitizing fresh produce involve various washing procedures.
Typically, fresh produce is washed with plain water or water containing a
sanitizer, such as chlorine; however, the researchers claim that chlorine has
a minimal effect in killing bacteria on these surfaces. Non-thermal
processing, of which ozone
gas is an example, can enhance food safety without compromising quality and
desirability of the food, claim the researchers. Objective
The
goal of this study, said Keener and Klockow, was to
analyse the effectiveness of a novel ‘in package’ ozone gas treatment PK-1
system, which uses a pair of electrodes with an adjustable gap inside a
package, in eliminating E. coli
0157:H7 on individual spinach leaves. The
authors said that another objective was the analysis of the effects of the
treatment and storage on the quality of the spinach leaves. Method Individual,
fresh, prepackaged, whole spinach leaves inoculated
with E. coli O157:H7 were treated in packaging with ozone generated in
air and oxygen. Samples were treated for five minutes and stored at room
temperature (22°C) or refrigeration (5°C) for 30 minutes, two hours and 24
hours. Gas
composition and relative humidity were measured. Results All
treated samples showed reductions in E. coli O157:H7 populations with
the largest reductions (3-5 log10 CFU/leaf) after 24 hours of storage. After
five minutes of treatment, ozone concentrations were 1.6 and 4.3 mg/L for air
and oxygen gas, respectively. The
concentrations of ozone decreased with time and were not detectable after 24
hours. A
five point Spinach Color Quality (SCQ) scale was
also established (5-best, 1-worst). Treated spinach showed discoloration with
SCQ-values of 3.83 and 1.00 for air and oxygen gas exposed leaves after 24
hours, found the scientists. The
authors concluded that the results indicate that the PK-1 system is capable
of reducing E. coli O157:H7 in packaged spinach; however, minimizing
quality changes after treatment requires further research. Source:
LWT - Food Science and Technology |
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