An investigation of green tea’s effect on mackerel (Scomber Scombrus)’s protein structure during frozen storage by FT-Raman spectroscopy

FT-Raman spectroscopy (FT-RS) was used to investigate green tea’s potential protective effect as an antioxidant during frozen storage of Atlantic mackerel (Scomber scombrus). Atlantic mackerel was stored for more than 26 weeks at −10°C or –80°C (control), with or without green tea (GT). Raman analysis showed substantial changes in protein structure due to frozen storage, especially at the higher storage temperature (−10°C), compared with the findings at −80°C or −10°C with instant GT, indicated by a decrease in the tyrosine doublet ratio, a-helix content. O-H stretching band intensity, along with an increase in tryptophan band intensity and β-sheet structure. GT as an antioxidant at a concentration of ~250 ppm can protect the structure of fish proteins for a limited storage period. However, for optimal freshness, fish should be stored at very low temperatures.