Abstract: The effect of storage time on the structure of myoglobin in beef was studied by Raman spectroscopy. The results showed that the α-helix content of myoglobin gradually decreased, the β-sheet content initially increased followed by a decrease, the β-turn content showed the opposite trend to β-sheet, and the random coil content increased progressively with increasing storage time. Furthermore, increasing storage time of beef resulted in configurational transformation of disulfide bonds in myoglobin from gauche-gauche-trans and trans-gauche-trans to gauche-gauche-gauche. Disulfide bonds were partially damaged and the intermolecular force of myoglobin reduced. The oxidation status of myoglobin had a strong correlation with the secondary structure and the amount of exposed tyrosine and tryptophan residues, respectively. The structure of myoglobin became disorderly scattered and the microenvironment of amino acid residues changed during storage. These results could explain the molecular mechanism of the effect of storage time on the color change of beef.

Key words: Raman spectroscopy, storage time, myoglobin, secondary structure