Changes in physicochemical properties and protein structure of surimi enhanced with camellia tea oil

The objective of this study was to determine the effects of different concentrations of camellia tea oil on surimi gel physicochemical properties and protein secondary structure. With the increase of camellia tea oil concentration (0-8 g/100 g of surimi), surimi gel hardness, whiteness, WHC, overall acceptability, storage modulus (G') and the indexes of ionic bonds and hydrophobic interactions were increased significantly (P < 0.05). Cryo-scanning electron microscopy (Cryo-SEM) showed that the oil occupied the void spaces of the protein matrix and formed a firmer structure. The Raman spectroscopy study showed that there was a decreased trend in alpha-helix content and increased trend in beta-sheet content in surimi protein as the oil content increased. Correlation analysis showed that the hardness was negatively correlated to the alpha-helix content (r = -0.958, P < 0.01) and positively correlated to the beta-sheet content (r - 0.958, P < 0.01) and hydrophobic interactions (r = 0.944, P < 0.01) of surimi gels. These results suggest that the presence of the oil could change the micro-environment and molecular structure of surimi proteins and further affect the physicochemical properties of surimi gels. In general, when the concentration of camellia tea oil was 8 g/100 g of surimi, the surimi gel showed the most favorable properties. (C) 2017 Published by Elsevier Ltd.