Relationship between Changes in Protein Characteristics and Quality Changes during Hot Air Drying of Shrimp (Penaeus vannamei)

In order to investigate the intrinsic relationship between protein characteristics and quality changes during the hot air drying of shrimp, Penaeus vannamei was dried by hot air at 55 ℃ after being boiled in 3% salt solution for 2 minutes. We studied changes in the microstructure and quality of shrimp, and systematically investigated changes in the oxidative degradation degree, intramolecular valence bonds, and secondary and tertiary structure of protein. The results showed that the drying treatment gradually decreased the L*, a* and b* values of shrimp, and changed the texture characteristics, and the hardness, adhesiveness and chewiness were increased to 344.78 N, 45.01 mJ and 116.50 mJ at the end of drying, respectively. In addition, oxidative denaturation and degradation of proteins occurred; the total sulfhydryl content decreased to 0.36 μmol/g at the end of drying, while the carbonyl content increased to 2.03 nmol/mg protein, and the trichloroacetic acid (TCA)-soluble peptide content increased to 0.91 μmol/g. The protein structure was significantly changed; the relative contents of ionic and hydrogen bonds decreased, the relative contents of hydrophobic and disulfide bonds increased, the secondary structure was transformed from α-helix to β-fold, β-turn and random coil, the intensity of tryptophan fluorescence decreased, and the tertiary structure was also changed. Pearson correlation analysis showed that the color changes were mainly related to protein oxidation and protein degradation and denaturation significantly affected the textural properties of shrimp. This study can provide theoretical support for further improving the quality of dried shrimp products.