Effect of residual oxygen on the colour, odour and taste of carbon dioxide-packaged beef, lamb and pork during short term storage at chill temperatures.

Samples of boneless pork, lamb, beef (high and normal pH) were packaged in '100%' carbon dioxide atmospheres in foil laminate pouches. These pouches were fitted with a septum and a gas sampling port that allowed the introduction of air and removal of gas samples for analysis from the sealed packs. After sealing, measured volumes of air were introduced into test packs that had been gassed at a carbon dioxide volume to meat weight ratio of either 1 litre/kg or 2 litres/kg, to give initial atmospheres containing approximately 0·1, 0·2 and 1·0% oxygen. After 24 and 168 h storage at -1·5 ± 0·5°C, test packs were removed and compared with similarly treated control packs without added oxygen with respect to meat odour, taste and colour. No significant differences between the test and control packs in respect to odour or taste were evident with any meat type. The tendency to develop browning in response to the presence of residual oxygen within packs, increased in the order: pork, normal pH beef, normal pH lamb, high pH beef. Beef and lamb developed noticeable browning in packs containing more than 0·15% total oxygen while pork was able to tolerate 1% oxygen without obvious detrimental effects. For all meat types, the colour stability was greater in packs gassed to the higher gas volume to meat weight ratio.