Reasons for Quality Deterioration of Obscure Pufferfish Fillets During Frozen Storage

This investigation aimed to compare the effects of ice crystals, endogenous proteases, and oxidation on the quality of obscure pufferfish (Takifugu obscurus) fillets during frozen storage, and detemine the dominant factors impacting their quality deterioration. The fillets were immersed in 1) liquid nitrogen, 2) iodoacetic acid solution, or 3) antioxidant mixtures (tea polyphenol and ascorbic acid solution), designed to inhibit the formation and growth of large ice crystals, activities of endogenous proteases, and the oxidization of proteins and lipids during storage, respectively. Therefore, the roles of these three factors in changing the quality of the frozen pufferfish fillets were differentiated. The hardness, thawing loss, cooking loss, total volatile basic nitrogen (TVB-N), K value, activity of Ca2+-ATPase, myofibril fragmentation index (MFI), and myofibril lengths were evaluated as quality indicators. The results showed that controlling the growth of ice crystals on the frozen pufferfish fillets had t