2.4. Measurement of carbon dioxide and ethylene production
Randomly selected fruits (approximately 200 g) from each replicate were placed in a 1-l sealed jar, with a septum in the lid, for sampling headspace gas. The fruits were allowed to equilibrate at room temperature for 2 h, and the jars were closed and kept for 3 h. A 1-ml sample of headspace gas was removed from each jar using a gastight syringe. Carbon dioxide and ethylene production were measured by a gas chromatography (GC) system (YL6500, YoungLin, Anyang, Korea) equipped with a thermal conductivity detector for carbon dioxide and a flame ionization detector for ethylene. Carbon dioxide was analyzed using a porapak column (1.5 m × 6 mm). Ethylene was analyzed using an alumina column (1.5 m × 6 mm). The oven, injector and detector temperatures were set at 70, 110 and 150 °C for carbon dioxide and 70, 110 and 250 °C for ethylene analyses, respectively.