Changes in muscle quality of Antarctic krill (Euphausia superba) during refrigerated storage: The role of protein degradation

The consumption proportion of Antarctic krill as a chilled food product has been gradually increasing. However, krill quality deteriorates significantly during refrigeration, and the mechanism behind this deterioration remains unclear. This study investigated the effects of refrigeration on the changes in krill quality and on the structure of krill myofibrillar proteins (MPs). The results indicated that during refrigeration, krill exhibited increased levels of trypsin activity, thiobarbituric acid reactive substances (TBARS), and total viable count, indicating heightened endogenous enzyme activity, oxidative reactions, and microbial activity. This process disrupted the integrity of the MPs' structure, degrading them into smaller fragments and leading to elevated myofibrillar fracture index (MFI) and total volatile basic nitrogen (TVB-N) levels. Macroscopically, MPs degradation and structural alterations manifested as localized fiber bundle ruptures within krill tissues, muscle structure collapse and softening, and severe moisture loss. By the final refrigeration stage, hardness and WHC reached minimum values of 211.70 g and 44.56 %, respectively, ultimately degrading krill edibility. Krill became inedible after 72 h of refrigeration. This study provided new insights into analyzing krill quality deterioration.