Dual role (promotion and inhibition) of transglutaminase in mediating myofibrillar protein gelation under malondialdehyde-induced oxidative stress.

This study investigated the effects of transglutaminase (TGase) on the properties of myofibrillar protein (MP) and its heat-induced gels under malondialdehyde (MDA)-induced oxidation. The physicochemical characteristics, protein aggregation and rheological properties of MP were assessed. The gelling behaviours of MP were analysed with measurements of gel strength, cooking loss, microstructure and secondary structure. Under varying degrees of MDA oxidation, the addition of TGase always led to changes in the tertiary structure, loss of free amine and thiol groups, crosslinking of the myosin heavy chain, and decreasing solubility. However, the effect of TGase on MP gel quality differed. At 6 mmol/L MDA, the addition of TGase reduced the quality of MP gels by increasing cooking loss. However, at 12 mmol/L MDA, TGase reduced both the cooking loss and gel strength.