Chinese Quince (Cydonia oblonga Miller) Freshness Rapid Determination Method Using Surface Acoustic Wave Resonator Combined with Electronic Nose

Figures & data

TABLE 1 Sensory evaluation scheme for quince samples

Attributes	Attribute degree
	5	4	3	2	1
Outward integrity	Firm	Integral	General integral	Slight crack	Much crack
Touch	Very hard	Hard	Slight soft	Soft	Very soft
Peel color	Green	Slight yellow	Yellow	Dark yellow	Brown
Shrinkage degree	None	Minor	Modest	large	Total
Glossiness	Very bright	Bright	Slight dull	Dull	Very dull
Rot degree	No rot	Little rot	Some rot	Major rot	Total rot

FIGURE 1 SAWR system: (a) schematic diagram of SAWR system; (b) detecting system; (c) equivalent model of SAWR in serial with quince sample.

FIGURE 2 Schematic diagram of EN detecting system.

FIGURE 3 Quality examining results: (a) human sensory evaluation; (b) weight loss.

FIGURE 4 Freshness predictive model using SAWR frequency output values.

FIGURE 5 EN analysis results and freshness predictive model based on EN system: (a) EN sensor array original responses to quince samples; (b) PCA score plot; (c) SR SNR spectrum; (d) freshness predictive model.

FIGURE 6 Validation experimental results for the predictive model based on (a) SAWR system; (b) EN system; and (c) SAWR combined with EN, respectively.