Changes in the autolysis level, muscle stability and myofibrillar protein properties of Antarctic krill (Euphausia superba) during refrigerated storage

Summary The aim of the study was to investigate the autolysis phenomenon in Antarctic krill during the buffer storage under refrigeration (after harvesting and before processing), groups of whole krill (WK) and of tail (TL) were stored at 4 °C and evaluated at 0, 6, 24, 36 and 48 h. The changes observed in visual appearance, sensory evaluation and meat yield jointly proved that severe autolysis had occurred, and this was more pronounced in the WK group than in the TL group. Meanwhile, the hardness of WK and TL groups decreased by 51.2% and 23.3%, and the shear force also decreased significantly from 3.26 N to 1.77 N and 2.28 N, respectively. Combined with the disrupted muscle microstructure and the conversion of bound water to immobilised water, the muscle tissue was found to be less stable as affected by the autolysis. The properties and structure of myofibrillar protein were dramatically changed, as revealed by the increased myofibril fragmentation index, decreased sulfhydryl content, and fluorescence intensity. Therefore, Antarctic krill can be deemed susceptible to autolysis during the buffer storage, especially whole krill. The information gained in this study improves our understanding of the effect of autolysis on muscle stability and its protein basis in Antarctic krill.