Fig. 1. Working principle of detection system

Fig. 2. Schematic diagram of device hardware
(a): Instrument strumcture diagram; (b): Physical drawing of instrument 1: Shell; 2: Vent; 3: Micro spectrometer; 4: Grip; 5: Upper cover and touch screen; 6: Raspberry Pi 4B; 7: Lug boss; 8: Light source control circuit board; 9: Card slot; 10: Testing accessories; 11: Power Supply

Fig. 3. Test accessories
1: Objective table; 2: Copper stud; 3: Light source seat; 4: Light source cover; 5: Sample pool; 6: Reflective cover; 7: Optical fiber collimating mirror; 8: Adjusting rod; 9: Swallowtail guide slide block; 10: Dovetail guide rail; 11: Support

Fig. 4. Spectra of flour samples with different quantities

Fig. 5. Light source control module
1: Circuit board; 2: Raspberry Pi 4B; 3: Lithium battery;4: 1 kΩ pull-up resistor; 5: Halogen lamp bead;6: TIP120 Darlington transistor

Fig. 6. Original spectra of flour

Fig. 7. Box plot graphics depicting the outliers in original spectra

Fig. 8. Box plot graphics depicting the outliers removed

Fig. 9. Savitzky-Golay smoothing

Fig. 10. Score plot of PCA

Fig. 11. PCA of modeling set samples

Fig. 12. Decision boundary

Fig. 13. Confusion matrix of LR prediction result

Fig. 14. LR ROC curves

Fig. 15. Testing system interface

Fig. 16. Work flow chart

Fig. 17. Test results of flour moisture

Table 1. Moisture measurement results of flour

Table 2. Measurement results of DON content in flour

Table 3. PLSR prediction models after different pretreatment

Table 4. Detection result of samples in external verification set