Electrical Stunning Has the Potential to Delay Fillet Degradation Post-Harvest in Red Seabream (Pagrus major)

Abstract

Ensuring the humane harvest of farmed fish without compromising the quality of the fresh product is paramount to the welfare of fish and in meeting consumer demands. Electrical stunning is a quick and effective way to render fish unconscious and it has emerged as the suggested harvest method by EFSA and OIE. The present study evaluated the effects of electrical stunning on the biochemical processes that lead to fillet degradation postmortem, in the red seabream (Pagrus major). Two distinct electrical stunning conditions (low and high) were compared along with the conventional harvest method (an ice slurry). The activity patterns of calpain, collagenase, and cathepsin B and L were assessed and compared to stereological changes in white muscles at different time points up to 13 days post-harvest. Histological examinations, independent of the harvest technique, revealed a progressively declining trend in fiber volume density and increasing interfibrillar spaces over time, indicative of degradation activity within and between the muscle fibers. Strong correlations between the stereological measures and the individual protease activities were recorded. The higher current condition (electric field 1.8 V/cm and velocity 1.6 m/s) consistently exhibited the lowest protease activity levels and the slowest pace of stereological changes, making it the suggested method of all harvest methods explored.