The post-storage respiration and ethylene
evolution measurements were recorded
using a static headspace technique [13]. Five
fruits from each replication were randomly
selected and enclosed in a hermetically
sealed container (1 L) with a twist-top lid fitted
with a silicone rubber septum. After an
hour of incubation at 25 °C, the headspace
gas was sucked through a hypodermic hollow
needle and the respiration rate was
quantified by using an auto gas analyser
(model: Checkmate 9900 O2/CO2, PBI
Dansensor, Denmark). The respiration rate
was expressed as mL CO2·kg–1·h–1. To
determine the ethylene evolution rate, a volume
of 1 mL of the headspace gas was withdrawn
through the septum using a Hamilton
gas-tight syringe and injected into a gas
chromatograph (model: Hewlett Packard
5890, USA). The gas chromatograph had
previously been calibrated using standard
ethylene gas (EDT Research, London, UK),
and was equipped with a flame ionisation
detector (FID) and Porapak-N 80/100 mesh
packed stainless steel column. Nitrogen was
used as the carrier gas at a flow rate of
30 mL·min–1, while the flow rates of the fuel
gases, H2 and air, were maintained at (30
and 300) mL·min–1, respectively. The temperatures
in the injector, column and detector
were adjusted to (110, 60 and 275) °C,
respectively. Results were expressed in
microlitres of ethylene released per kg of
fruit per hour (µL·kg–1·h–1).