Packaging gas selects lactic acid bacterial communities on raw pork

Area of Science:

• Food Microbiology
• Meat Science
• Microbial Ecology

Background:

• Lactic acid bacteria (LAB) are crucial for raw meat quality and safety.
• Modified atmosphere packaging (MAP) is widely used to extend the shelf life of raw meat.
• Understanding LAB community dynamics under different MAP conditions is essential for effective meat preservation.

Purpose of the Study:

• To investigate the influence of various carbon dioxide (CO2)-rich packaging atmospheres on the proliferation and composition of lactic acid bacterial communities on raw pork.
• To determine how different gas compositions in MAP affect the selection of specific LAB genera on raw meat.

Main Methods:

• Raw pork loin was inoculated with a defined mixture of 14 LAB strains.
• Pork was packaged under four different gas atmospheres: 100% CO2, 80% N2/20% CO2, 80% N2/20% CO2/0.4% CO, and 80% O2/20% CO2.
• LAB counts, pH, and gas composition were monitored over 14 days at 6°C.
• Bacterial community composition was analyzed using culture-independent (T-RFLP) and culture-dependent (ribopattern analysis) methods.

Main Results:

• High CO2 concentrations in the packaging atmosphere selectively promoted the growth of Lactobacillus species.
• The presence of high O2 concentrations favored the proliferation of Leuconostoc species.
• An atmosphere of 80% N2 and 20% CO2 was found to favor the dominance of Lactococcus species.

Conclusions:

• The composition of the modified atmosphere packaging is a critical determinant in shaping the lactic acid bacterial communities on raw meat.
• These findings offer insights into the observed LAB compositions in MAP raw meat and can guide strategies for manipulating LAB through protective cultures.