In this study, hyperspectral cameras of 400-1000nm band and 900-1700 nm were applied, and FS13 and FS15 products of Hangzhou Color Spectrum Technology Co., Ltd. could be used for related research. The spectral range is 400-1000nm, the wavelength resolution is better than 2.5nm, and up to 1200 spectral channels can be reached. The acquisition speed can reach 128FPS in the full spectrum, and the maximum after band selection is 3300Hz (support multi-region band selection).
Meat mainly includes livestock and poultry and aquatic products, proteins, fatty acids, trace elements and other important energy substances needed by the human body are derived from meat. With the continuous improvement of living standards, people pay more attention to the quality of food and balanced nutrition in the diet, but some illegal businesses will mix some low-quality meat into high-quality meat, shoddy, especially in 2013 Europe's "horse meat wave", triggered people's extreme concern about meat adulteration. Meat adulteration detection methods include sensory evaluation, fluorescent PCR detection technology, electrophoresis analysis and enzyme-linked immunoassay technology, etc., but most of them require sample pretreatment, and the test operation is complicated and time-consuming, and it is difficult to achieve rapid real-time detection of large sample size in the field.
Most of the existing literature reports used single-band hyperspectral imaging technology to distinguish meat adulteration, but few used two bands for comparative analysis. In this experiment, high-quality defrosted mutton was selected as the adulterant, and duck meat with relatively low price was doped. Hyperspectral information of samples was collected in the two bands of visible near-infrared (400 ~ 1 000 nm) and short-wave near-infrared (900 ~ 1700 nm), and a quantitative model was established by selecting appropriate pretreatment methods. The optimal model was selected for image inversion, and a visualization method for rapid quantitative detection of mutton adulteration was proposed in order to provide data and technical support for the quantitative detection of mutton adulteration.
(1) For the band of 400 ~ 1000 nm, the full-band PLS model established after normalization pretreatment has the highest accuracy; For the 900-1700 nm band, the full-band PLS model established after SNV pretreatment has the highest accuracy. By selecting the wavelength of the two spectral bands under the optimal pretreatment method, it is found that the collinearity between the selected wavelengths is minimal and representative on the basis of eliminating multicollinearity, which can further improve the accuracy and simplicity of the model.
(2) There is more information about groups related to meat composition in the 900-1700 nm band, which can better reflect the characteristics of meat, and may be more suitable for the identification of meat adulteration. In order to enlarge the comprehensiveness and applicability of the model, the experiment should be extended to the long wave near infrared spectrum (1 700 ~ 2500 nm). At the same time, the high-quality mutton and duck meat selected in the experiment were packaged as finished products in local supermarkets. Whether the subsequent model can be applied to the study of mutton adulteration under different environments (temperature, humidity, shape, etc.), different varieties, different qualities, different feeding methods and different freshness needs further verification and discussion.