2.6. Analysis of gases
The concentration of oxygen and carbon dioxide was measured by a gas analyser according to the manufacturer's instructions (Model CheckMate 9900, PBIDansensor A/S, Ringsted, Denmark). The gas composition was evaluated at the moment of sampling by inserting a needle into the package. This needle is connected by a plastic tube to the gas analyser that determines the gas composition. Prior to measurement the gas analyser was checked by measuring the atmospheric gas composition (i.e. 20.9% oxygen and 0.04% carbon dioxide). The values are the mean of duplicate samples.