Electronic Nose
The electronic nose applied in the experiment is also developed
by our own laboratory (Hu 2011). It consists of a
sampling system, a detector containing the array of sensors,
and pattern recognition for data recording (Fig. 1b). The
sensor array is composed of ten different metal oxide sensors.
Each sensor has a certain degree of affinity toward specific
chemicals or volatile compounds. Table 1 shows all the sensors
and corresponding applications. The sensors’ response on
changes in conductivity induced by the adsorption of gasphase
molecules and on subsequent surface reactions.
Before the measurement, the system of electronic nose was
cleaned with zero-air which was indoor air-filtered by activecarbon. The main purpose of zero-air was to clean the circuit
and to return the sensors to the baselines. During the measurement
of rice, the headspace gas of a sample was pumped into
the sensor chamber at a constant rate of 0.5 L/min through a