Recently, I was doing some reading and while I found a lot of research on veggies, fruits and red meats, there seemed to be less on poultry and modified atmosphere packaging. Two of the studies are reviewed in brief below.
In a study published in August of 2006 (Food Microbiol. 2006 Aug;23(5):423-9. Epub 2005 Oct 18.), the lab of Dr. Kontominas examined the effect of three different MAP gas blends on the shelf-life of precooked chicken. The three blends CO2/N2 tested (along with an aerobic control) were:
M1: 30% CO2/70% N2
M2: 60% CO2/40% N2
M3: 90% CO2/10% N2
The team monitored total viable counts (TVC), Lactic acid bacteria (LAB), Brochothrix thermosphacta, pseudomonads, yeasts and molds, and Enterobacteriaceae at 0, 4, 8, 12, 16 and 20 days. They found that using MAP extended the shelf life in all cases. The M1 gas mixture extended the shelf-life by 4 days, while the shelf-life was extended by greater than 6 days for the M2 and M3 gas mixtures. Additionally, they found that the M2 and M3 preserved the taste and smell of the precooked chicken right up until the 20th day of the testing. (For the full study, click here).
Dr. Kontominas’ lab also conducting an interesting set of experiments to examine the impact of adding oregano essential oil when packaging fresh chicken under modified atmosphere (Food Microbiol. 2007 Sep; 24(6):607-17. Epub 2007 Jan 12.).
In this study, oregano essential oil was added during MAP at either 0.1% or 1.0% (w/w). The MAP gas blends utilized were 30% CO2/70% N2 (M1 above) and 70% CO2/30% N2. The fresh chicken breasts were evaluated over the course of 25 days. As in the first study, the team monitored total viable counts (TVC), Lactic acid bacteria (LAB), Brochothrix thermosphacta, pseudomonads, yeasts and molds, and Enterobacteriaceae, as well as examining odor and taste. They also checked pH and color.
In brief, they found:
A “more pronounced effect” on microbial reduction when oregano essential oil was combined with MAP (1-5 log cfu/g).
No real effect on color with MAP or with a combination of MAP and essential oil.
A strong taste effect with oregano oil at a concentration of 1%, and it was therefore excluded from the final evaluation/comparison.
Sensory evaluation (taste and smell) showed a shelf-life extension of 3-4 days when containing 0.1% essential oil, 2-3 days for samples using MAP and 5-6 days when the two were used in combination.