Abstract: The pattern of changes in water mobility, protein structure and texture characteristics in Takifugu obscurus meat under low temperature storage (10, 4 and ?3 ℃) was explored, and the correlations of transverse relaxation times with texture parameters, protein properties and structure were evaluated to explore a rapid method to monitor quality changes of Takifugu obscurus under low temperature storage. The results showed that prolongation of the storage time led to increased T2b (bound water) and T22 (free water) and alternate increase and decrease in T21 (immobilized water). Elasticity and hardness showed a downward trend for all temperature groups, with the ?3 ℃ group exhibiting the highest cooking loss rate, centrifugal loss rate and drip loss rate. Scanning electron microscopic (SEM) analysis indicated that superchilling (?3 ℃) could destroy fish muscle fibers, thus affecting the texture and water-holding capacity. During low temperature storage, the contents of disulfide bonds, carbonyl groups and total free amino acid (FAA) increased, whereas the content of sulfhydryl groups and Ca2+-ATPase activity decreased. The results of Fourier transform infrared spectroscopy showed that the relative contents of α-helix and β-sheet decreased and increased in a fluctuant fashion, respectively. Correlation analysis showed that T2b and T22 in all temperature groups were significantly correlated with centrifugal loss rate, drip loss rate, disulfide bond content, β-sheet relative content relative, total FAA content, sulfhydryl content, Ca2+-ATPase activity, endogenous fluorescence intensity and elasticity (P < 0.01 or 0.05), demonstrating that changes in transverse relaxation times are useful to quickly predict quality changes of Takifugu obscurus during low temperature storage.

Key words: Takifugu obscurus; low temperature storage; moisture; protein; texture