Effects of Ionic Strength on Water-holding Capacity and Properties of Myofibrillar Protein of Antarctic Krill Meat

To address the issues of fluid loss and tough texture in Antarctic krill meat, the impact of soaking times and solutions of varying ionic strengths (0.8, 0.9, 1.0, and 1.1 mol/L) on the properties of myofibrillar proteins (MPs) and water-holding capacity of Antarctic krill myofibrillar protein (1, 2, 4, and 6 h) was investigated in aspects of centrifugal loss, water distribution, hardness, myofibril fragmentation index (MFI), protein surface hydrophobicity, protein composition and protein secondary structure. Results demonstrated that with an increase in ionic strength, there was an initial decrease followed by an increase in cooking loss, centrifugal loss, and hardness, along with an increase in immobilized water content, superior to the control group (P<0.05). Under the same ionic strength conditions, the water-holding capacity of krill meat was demonstrated to be optimal after 2 h soaking. When the krill meat was immersed in a soaking solution with a concentration of 1.0 mol/L for 2 h, the springiness increased from 0.76 to 0.98, and the hardness reduced from 241.99 g to 102.66 g. The myofibril fragmentation index of krill meat was the highest, measuring 11.43. The protein surface hydrophobicity dropped from 9.85 μg to 1.83 μg. The protein content in β-sheet structures exhibited an initial increase followed by a subsequent drop as the ionic strength increased after a 2 h immersion period. High ionic strength of 1.1 mol/L leads to excessive protein aggregation, resulting in severe damage to the muscle fiber tissue and negatively impacting its water-holding ability. Combined with sensory evaluation, the immersion solutions with ionic strength of 1.0 mol/L and soaking duration of 2 h improved the water-retentive capacity of Antarctic krill meat, establishing a theoretical guideline for Antarctic krill meat processing.