Microbiological, physicochemical and sensory characteristics of Cameros cheese packaged under modified atmospheres

This study evaluated the shelf-life quality of Cameros cheeses packaged under modified atmospheres. Five different modified atmosphere conditions were studied (carbon dioxide/nitrogen mixtures and vacuum) Control cheeses were packaged in air. The product stored at 3-4 degrees C was evaluated periodically to investigate its sensory quality microbiological condition and physicochemical characteristics Weight loss and pH evolution were similar in vacuum and air packaging. Cheeses packaged in 100% CO2 showed the greatest weight losses and lower pH values. CO2 reduced proteolysis and lipolysis during storage in ail conditions studied. Fat acidity and NPN/TN values were slightly higher in vacuum than in CO2, hut lower than in air. Modified atmosphere packaging presented an extended shelf life. Those containing CO2 reduced the growth rate of mesophiles, psychrotrophs, Enterobacteriaceae and coliforms, which was lower when the CO2 concentration increased. The lowest microbial counts were at 100% CO2 while vacuum conditions presented microbial counts only slightly lower than the controls. Salmonella spp., Staphylococcus aureus and Listeria spp were not found in any of the samples. Faecal coliforms, moulds and yeasts were not detected under CO2 atmospheres or in vacuum. After 7 days of storage, the sensory characteristics of the control cheeses were unacceptable in all the parameters studied. However, the overall score for cheeses stored in 40% and 50% CO2 did not change substantially, retaining a reasonable acceptability until the end of the storage period. The 100% CO2 atmosphere had a very negative effect on sensory quality. With regard to Cameros cheese, packaging in 50% CO2! 50% N-2 and 40% CO2/60% N-2 are the most effective for extending shelf life and retaining good sensory characteristics (C) 2000 Academic Press.