Inhibition of interaction between epigallocatechin-3-gallate and myofibrillar protein by cyclodextrin derivatives improves gel quality under oxidative stress

High levels of polyphenols can interact with myofibrillar proteins (MPs), causing damage to a MP emulsion gel. In this study, beta-cyclodextrins were used to reduce covalent and non-covalent interaction between epigallocatechin-3-gallate (EGCG) and MPs under oxidative stress. The loss of both thiol and free amine groups and the unfolding of MPs caused by EGCG (80 mu M/g protein) were significantly prevented by beta-cydodextrins, and the structural stability and solubility were improved. MP emulsion gel treated with EGCG (80 mu M/g protein) had the highest cooking loss (68.64%) and gel strength (0.51 N). Addition of beta-cyclodextrins significantly reduced cooking loss (26.24-58.20%) and improved gel strength (0.31-0.41 N) of MP emulsion gel jeopardized by EGCG under oxidative stress. Damage to the emulsifying properties of MPs caused by EGCG was significantly prevented by addition of beta-cyclodextrins. beta-cyclodextrins reduced interaction between EGCG and MPs in the order Methyl beta-cyclodextrin > (2-Hydroxypropy1)-beta-cyclodextrin > beta-cyclodextrin. In absence of EGCG, addition of beta-cyclodextrins partly protected MPs from oxidative attack and improved its solubility. It is concluded that beta-cyclodextrins does not markedly reduce the antioxidant ability of EGCG according to carbonyl analysis, and can effectively increase EGCG loading to potentially provide more durable antioxidant effect for meat products during processing, transportation and storage.