Effect of Storage Time and Packing Method on the Freshness of Dried Lycium Fruit Using Electronic Nose and Chemometrics

Table 2

Sensors used and their main applications in PEN 2 electronic nose.

Number in array	Sensor name	General description	Reference
S1	W1C-aromatic	Aromatic compounds	Toluene, 10 ppm
S2	W5S-broad range	Very sensitive, broad-range sensitivity, react on nitrogen oxides, very sensitive with negative signal	NO2, 1 ppm
S3	W3C-aromatic	Ammonia, used as sensor for aromatic compounds	Benzene, 1 ppm
S4	W6S-hydrogen	Mainly hydrogen, selectively (breath gases)	H2, 100 ppb
S5	W5C-arom-aliph	Alkanes, aromatic compounds, less polar compounds	Propane, 1 ppm
S6	W1S-broad-methane	Sensitive to methane (environment) ca, 10 ppm, broad range, similar to no.8	CH4, 100 ppm
S7	W1W-sulfur-oganic	Reacts on sulfur compounds, H2S 0.1 ppm; otherwise, sensitive to many terpenes and sulfur organic compounds, which are important for smell, limonene, and pyrazine	H2S, 1 ppm
S8	W2S-broad-alcohol	Detects alcohols, partially aromatic compounds, broad range	CO, 100 ppm
S9	W2W-sulph-chlor	Aromatic compounds, sulfur organic compounds	H2S, 1 ppm
S10	W3S methane-aliph	Reacts on high concentration >100 ppm, sometime very selective (methane)	CH4, 100 ppm