Characterization of lipid oxidation process of beef during repeated freeze-thaw by electron spin resonance technology and Raman spectroscopy

Abstract In this study, electron spin resonance (ESR) and Raman spectroscopy were applied to characterize lipid oxidation of beef during repeated freeze–thaw (RFT). Besides the conventional indexes including peroxide values (PV), thiobarbituric acid-reactive substances (TBARS) and acid values (AV) were evaluated, the radical and molecular structure changes were also measured by ESR and Raman spectroscopy. The results showed that PV, TBARS and AV were increased (P  ν (C C) stretching region (1655 cm −1 ) was decreased during RFT. Furthermore, lower Raman intensity ratio of I 1655 /I 1442 , I 1655 /I 1745 that determine total unsaturation was also observed. Significant correlations (p