Abstract: The objective of this study was to investigate the effects of tea polyphenols (0, 0.02, 0.2 and 1.0 mg/mL) on the side chain structure, water-holding capacity (WHC) and water distribution state of myofibrillar protein (MP) in hydroxyl radical oxidation system. Results showed that oxidative stress to MP significantly decreased free sulfydryl content and WHC, significantly increased surface hydrophobicity, dityrosine content and free water content, and lowered endogenous tryptophan?fluorescence intensity compared to the non-oxidized control (P < 0.05). Under oxidative conditions, free sulfydryl content and endogenous tryptophan?fluorescence intensity gradually increased, surface hydrophobicity decreased, and WHC of MP gels rose with increasing concentration of tea polyphenols; immobilized water content significantly increased while free water content significantly declined (P < 0.05). Tea polyphenols can protect the side chain structure of MP and improve the WHC of heat-induced gels under oxidative conditions.

Key words: myofibrillar protein oxidation, tea polyphenol, low-field nuclear resonance (LF-NMR), physicochemical properties