Application of long-wave near infrared hyperspectral imaging for measurement of color distribution in salmon fillet

This study was carried out for rapid and non-invasive measurement of color distribution in salmon fillet using hyperspectral imaging in long-wave near infrared spectral range (LW-NIR). Successive projections algorithm (SPA) was used to select effective wavelengths. Instead of selecting different sets of effective wavelengths for each color component respectively, instrumental effective wavelengths (IEWs) were identified for the prediction of all three color components, leading to reducing the number of band-pass filters for designing the multispectral imaging system. Meanwhile, predictive effective wavelengths (PEW) were further chosen from IEW to optimize calibration models. The final prediction models were considered as the multiple linear regression (MLR) models with PEW, which resulted in correlation coefficients (rC) of 0.876, 0.744, and 0.803 for L*, a*, and b*, respectively. Finally, the visualization of color distribution in salmon fillets was achieved. The results demonstrated that LW-NIR hyperspectral imaging is a potential technique to quantitatively measure color distribution of salmon fillet in a rapid and non-invasive way.Industrial relevance: This study was conducted to evaluate the feasibility of a hyperspectral imaging system in the LW-NIR spectral region (964 to 1631 nm) for rapid measurement of color in intact salmon fillets. On the basis of the results and accompanying illustrations presented in this work, the study demonstrated the ability of the method based on LW-NIR hyperspectral imaging to measure color distribution of salmon fillets. This method was a rapid, contact-free, and consistent evaluation, and can be used as a reliable and rapid alternative to traditional colorimeter for measuring color of salmon fillet for the food industry.

► First time LW-NIR hyperspectral imaging was used to measure color of salmon fillet.
► Instrumental effective wavelengths were selected for multispectral imaging system.
► Predictive effective wavlengths were further selected for optimizing models.
► MLR equations via effective wavelengths were obtained for measuring L*, a*, and b*.
► Color distribution of salmon fillet was visualized at pixel-level.