Evaluation of quality parameters and shelf life of fresh cheese packed under modified atmosphere

Fresh (acid coagulated) cheeses belong to a group of soft unripen cheeses which are very popular among consumers. However, owing to the specific composition and properties, these cheeses have a limited shelf life. The aim of this study was to investigate the effect of modified atmosphere packaging (MAP) onto fresh cheese and to compare it with the commonly used packaging under atmospheric air and vacuum. The produced fresh cheese was packed under normal atmosphere (air), vacuum and modified atmosphere of following composition: (1) 60%N₂:40%CO₂; (2) 70%N₂:30%CO₂. All cheese samples were cool stored for 18 days, whereby the sampling and analyses were conducted every 3 days. During the storage period, there was a continuous decrease in acidity (from 4.66 to 4.47), while the viable counts of the monitored microorganisms increased in the control sample. However, in samples packaged under vacuum and modified atmosphere a slighter decrease in acidity (no result under 4.50) and inhibited microbiological growth were detected. Scores of sensory evaluations were high for all samples (17.63-19.73), whereby the sample packed under MAP with ratio 70%CO₂:30%N₂ obtained the best average score of 17.72 at the end of the 18-day storage period. Other analyses confirmed that vacuum and MAP prolong the shelf life of fresh cheese while preserving its physico-chemical and sensory characteristics.