3. Gas analysis About 0.3ml of the headspace gas was periodically sampled from the package and was injected in the gas chromatograph. A small silicone rubber piece (ca.l0mm × 10mm) was glued on the surface of the package so that the gas sampling was easily carried out by direct sticking of a syringe needle into the package. 4. Calculation of gas composition The gas chromatographic profile of a gas mixture including N2, O2, CO2 and Ar is sche- matically given in Fig. 2. Peak A to B and Peak C to F indicate the gas portions separat- ed by the columns packed with activated charcoal and Gaskuropack 54, respectively