The effect of carbon dioxide on the growth of Penicillium camemberti

Penicillium camemberti strains were inoculated on a whey-based medium and incubated in modified atmosphere (MA) chambers where O 2 levels were initially adjusted between 10-40% and CO 2 concentrations to a 10-30% range. There were no significant differences in the growth patterns of the two strains submitted to the various atmospheres. When MA conditions were applied to P. camemberti cultures at the very beginning of incubation, CO 2 concentration was highly inhibitory to the growth of the strains; the higher the initial concentration of CO 2 the slower was the observed growth. In treatments with initial levels of 21 % of O 2 and no CO 2 (air control), a gradual increase in carbon dioxide was noted and its concentration could reach 7% after 23 days at 1°C. In treatments where 10-30% CO 2 was initially injected, a decrease in atmospheric carbon dioxide in the MA chamber occurred at the beginning of incubation (by half in the initial 30% CO 2 treatment), which was then followed by slight increases. Concentrations of 10, 30 and 40% of O 2 did not generate different growth curves compared with those obtained in air. These results suggest that MA packaging has the potential of influencing Penicillium with the aim of increasing the shelf-life of mold ripened cheeses such as Camembert or Brie.