Insights into the potential mechanism of liquid nitrogen spray freezing's influence on volatile compounds in surimi gels with different cross-linking degrees: Focus on oxidation, protein structure, intermolecular force and free amino acid alterations

Abstract

This study revealed the variations in odor characteristics and underlying mechanisms of different cross-linked surimi gels under liquid nitrogen (LN) spray freezing. The results demonstrated that LN spray freezing had an essential effect on the gels′ odor. The odor changes in the −80 °C LN spray freezing group were closer to the control group, while −35 °C LN spray freezing treatment had the greatest impact on the aroma quality of gels. Freezing reduced gels′ texture properties, intensified lipid and protein oxidation, altered protein conformation, increased surface hydrophobicity and hydrophobic interactions. These changes affected the gels' odor characteristics, leading to a reduction in fish aroma and an increase in fishy and oil odors after freezing. These tendencies were more pronounced at −35 °C LN spray freezing with lower cross-linking degrees, and reducing the freezing temperature to −80 °C and increasing the cross-linking degree to 62.99% mitigated the extent of deterioration in gel flavor quality.