Non-destructive assessment of oxygen levels in industrial modified atmosphere packaged cheddar cheese

An optical oxygen analyser was used in a small-scale industrial trial to non-destructively assess modified atmosphere packaged (MAP) cheese and the packaging process. Sixty seven samples of cheddar cheese, packaged under standard MAP conditions of 70% N2: 30% CO2 were monitored for residual oxygen using disposable sensor “stickers” incorporated in each pack and a benchtop optical analyser. Three faulty packs with oxygen leaks were identified in days 1, 4 and 11 after packaging, while in the remaining packs low levels of residual oxygen (<0.75%) were observed, as expected. Residual oxygen was monitored over 4 months of product shelf life at +4 °C, along with measurement of microbial growth. Good correlation between this system and established (destructive) methods of quality assessment of food packs was found. The optical oxygen sensor system was shown to provide valuable information about performance of the packaging process, product storage conditions and food quality in a convenient, non-destructive and cost-efficient fashion.