Vibrational spectroscopy and biochemical changes in silver carp as related to quality of washed mince.

BACKGROUND: Biochemical and protein conformational changes in silver carp occurred during ice storage, affecting the physico-chemical and textural properties of its washed mince. Fourier-transform infrared spectroscopy (FTIR) and FT Raman could offer insightful molecular-level information that could be related to the freshness of fish and textural properties of washed mince. RESULTS: The K value increased from 15.8% to 85.0% after 14 days on ice. The surface hydrophobicity of silver carp muscle proteins increased during ice storage, and its thrice-washed mince showed the same trend. The yield and textural properties of washed mince continually decreased as the storage time was extended. Fourier-transform infrared spectroscopy revealed that, as storage time increased, the α-helix content of mince decreased, while the ß sheet content increased. Prolonged ice storage led to the exposure of buried aromatic amino acid residues and an increase in disulfide interchanges in mince and washed mince. Changes in the ∑ß sheet structure and Raman intensity at 828 cm-1 observed in mince correlated well with the K value. The α-helix content and Raman intensity of raw washed mince at 621 and 828 cm-1 showed a strong correlation with its textural properties. CONCLUSION: Silver carp should be processed to surimi within 7 days of ice storage to obtain a reasonably good yield and gel texture. Infrared and Raman spectroscopy can possibly be utilized to monitor freshness quality and protein conformational changes in silver carp and to estimate the textural properties of washed mince as affected by freshness. © 2019 Society of Chemical Industry.