The study from the University of Georgia in the US shows that antimicrobial packaging with an O2 scavanger or CO2 generator inhibits the development of listeria on ready-to-eat meat products.
The article, entitled ‘Use of Active Packaging Structures to Control the Microbial Quality of a Ready-to-Eat Meat Product’, said that antimicrobial packaging was one of most promising applications of active food packaging technology as it “controls spoilage as well as contamination with pathogens”.
Researchers J. Chen and A. L. Brody defined antimicrobial packaging as packaging incorporating technology that modifies the headspace atmosphere around the product to create a hurdle against bacterial cells. For this study, they looked at using carbon dioxide (CO2), oxygen (O2) and an allyl isothiocyanate (AIT) generator.
The article said the control of L. Monocytogens was vital, because product recalls had brought "devastating losses" to the US food industry, especially as the United States Department of Agriculture (USDA) has imposed a zero policy against the pathogen on ready-to-eat food
Between 2003 and 2011 there were 519 food product recalls in the country and more than one-fifth – 21% - were associated with L. monocytogenes, according to figures from the USDA Food Safety and Inspection Service (FSIS). That amounts to 6.5 million lbs (2.9 million kilos) of wasted food.
The researchers inoculated cooked ham samples, each weighing 25g, with a five-strain mixture of L. monocytogenes, then packaged them into three different antimicrobial packaging structures. Some samples were packaged in non-antimicrobial packaging as controls.
The packaging used in this study included a nylon/EVOH/PE oxygen barrier bag and an antimicrobial film, with the capacity of generating CO2, O2 or AIT, which then migrated through the polymer.
The samples were stored at 4˚C, 10˚C or 22˚C, and the populations of aerobic bacteria were measured twice a week over a four-week period.
The researchers found that the antimicrobial packaging structures with the CO2 generator and O2 scavenger were significantly effective in controlling the growth of inoculated L. monocytogenes on cooked ham samples. The most effective inhibition of the pathogens occurred at 22°C.
Listeria populations in the packaging structure with the O2 scavenger were 1.80-2.65, 3.69-4.76, and 4.62-4.67 log CFU g-1 lower than the controls samples at 4°C, 10°C, or 22°C.
Samples in the packaging structure with the CO2 generator were 1.11-1.63, 4.30-4.45, and 4.01-4.44 logCFU g-1 lower than the controls at 4°C, 10°C, or 22°C
Populations of Enterobacteriaceae on the ham samples were also significantly reduced. However, the packaging with an AIT generator only had a limited antimicrobial effect.
Title: 'Use of Active Packaging Structures to Control the Microbial Quality of a Ready-to-Eat Meat Product'
Authors: J. Chen, A. L. Brody
Source: Food Control. Published 3 July 2012 http://dx.doi.org/10.1016/j.foodcont.2012.07.002