Improvement of Water Retention Quality of Beijing Roast Duck: Analysis from Protein Structure Perspective

Abstract

Water loss from Beijing roast duck has always been a problem in the food industry. The relationship between the protein structural changes and water migration during the roasting process of Beijing roast ducks was evaluated using Fourier transform infrared spectroscopy and low-field nuclear magnetic resonance. The secondary structure analysis showed a decrease in the α-helix content from 25.58% to 19.24%, whereas the β-sheet, β-turn, and random coil contents increased. Furthermore, the decrease in the α-helix content resulted in the release of more water from the meat proteins, which was accompanied by an increase in the β-turn and random coil content. In addition, the surface hydrophobicity of the actomyosin gradually increased from 12.12 μg to 41.63 μg during heating (P < 0.05). With an increase in the center temperature, the water content rapidly decreased, the immobilized water content decreased, and the amount of free water increased significantly. Therefore, the accelerated loss of water can be attributed to the gradual expansion of the protein structure and an increase in the surface hydrophobicity of the Beijing roast duck.

Keywords: roast duck, Myofibrillar protein, water transfer, Secondary structure, surface hydrophobicity