Microbiological and biochemical aspects of Camembert-type cheeses depend on atmospheric composition in the ripening chamber

Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical dynamics were studied in relation to ripening chamber CO2 atmospheric composition using 31 descriptors based on kinetic data. The chamber ripening was carried out under 5 different controlled atmospheres: continuously renewed atmosphere, periodically renewed atmosphere, no renewed atmosphere, and 2 for which CO2 was either 2% or 6%. All microorganism dynamics depended on CO2 level. Kluyveromyces lactis was not sensitive to CO2 during its growth phases, but its death did depend on it. An increase of CO2 led to a significant improvement in G. candidum. Penicillium camemberti mycelium development was enhanced by 2% CO2. The equilibrium between P. camemberti and G. candidum populations was disrupted in favor of the yeast when CO2 was higher than 4%. Growth of B. aurantiacum depended more on O-2 than on CO2. Two ripening progressions were observed in relation to the presence of CO2 at the beginning of ripening: in the presence of CO2, the ripening was fast-slow, and in the absence of CO2, it was slow-fast. The underrind was too runny if CO2 was equal to or higher than 6%. The nitrogen substrate progressions were slightly related to ripening chamber CO2 and O-2 levels. During chamber ripening, the best atmospheric condition to produce an optimum between microorganism growth, biochemical dynamics, and cheese appearance was a constant CO2 level close to 2%.