Effect of pH on the interaction of porcine myofibrillar proteins with pyrazine compounds.
The influence of pH-induced structural modifications of myofibrillar proteins (MPs) on their interaction mechanisms with pyrazine compounds was investigated. At a lower pH (4.9, 5.5), MPs aggregated to larger particle sizes due to enhanced the protein-protein interactions. The binding with pyrazine compounds was strongly affected by pH and the nature of flavor compounds. MPs exhibited flavor releasing behavior, probably due to protein-protein interactions and surface tension. Fluorescence analysis revealed that the interaction of pyrazine compounds with MPs followed a combination of static and dynamic quenching. The changes in quenching constant (Ksv) might be attributed to a dynamic quenching, probably due to protein aggregation. The percentages of free 2,5-Dimethylpyrazine (2,5-DMP) were similar to Ksv. Thermodynamic parameters indicated that electrostatic interactions and hydrophobic interactions were the major acting forces in the binding of MPs to 2,5-DMP. The binding of 2,5-DMP increased the α-helix content of MPs.