Oxidatively induced chemical changes and interactions of mixed myosin, β-lactoglobulin and soy 7S globulin

The effects of oxidation on the chemical characteristics of myosin, β-lactoglobulin and soy 7S globulin were investigated in a free radical-generating system (FeCl₃/H₂O₂/ascorbate). Oxidised myosin exhibited a marked increase (> 10-fold) in carbonyls, a small increase in amines and conversion of some free sulphhydryls to disulphide bonds. Oxidised β-lactoglobulin and 7S globulin also showed a major increase in the carbonyl content (five- and threefold respectively), but other chemical changes were relatively minor. In the oxidised myosin/β-lactoglobulin composites, some cross-linked aggregates were formed. Aggregation was also evidenced in the myosin/7S globulin composites exposed to the oxidising agents. The results indicated that oxidation enhanced interactions of the non-muscle proteins with myosin apparently through the modification of amino acid side chains. These physicochemical changes may influence the functionality of processed muscle foods. (C) 2000 Society of Chemical Industry.