Evaluation of Post‐Mortem Colour Changes in Fish Eye, Gills and Skin Using Hyperspectral Imaging

Freshness is one of the critical attributes of fish quality and is of great importance in aquaculture, as post‐mortem changes can affect consumer acceptance and market value. This study aims to assess the potential use of hyperspectral imaging to determine colour parameters and monitor colour changes in three aquaculture fish species ( Sparus aurata , Dicentrarchus labrax and Pagrus major ) during storage. Hyperspectral images were collected over 10 days of storage in ice starting on the third day post‐harvest. Reflectance images were calculated, and region of interest, ROIs (eye, gill and body parts), were identified. The reflectance images were transformed into the CIE colour space, and (lightness), (green to red) and (blue to yellow) were estimated. Additionally, spectral signatures for each ROI were obtained. A significant increase of on the eye and a decrease of on the gill was observed for all species during storage time, while in Pagrus major there was also a decrease of the and in the dorsal and ventral skin areas. Significant relationships were found between the sensory score, obtained by a pilot sensory evaluation, and the colour values, associating the deterioration of quality with the post‐mortem colour changes observed. This work demonstrates the potential of hyperspectral imaging as a tool to evaluate external fish colouration in relation to fish quality deterioration.