Alkali-aided protein extraction from chicken dark meat: Chemical and functional properties of recovered proteins

Alkali-aided extraction of proteins from chicken thigh meat has been attempted for improved utilization of this low value raw material. This study focused on chemical and functional properties of proteins recovered after extraction in alkaline conditions at pH values of 10.5, 11.0, 11.5 and 12.0. Solubility of total proteins was significantly reduced (P < 0.0001) for proteins extracted at higher pH (11.5 and 12.0) with a significant increase in protein hydrophobicity. Despite the lower protein solubility, protein recovery yield was found to be higher at pH values of 11.5 and 12.0. Reactive sulfhydryl content also significantly increased (P < 0.05) for these two treatments. Alkali treatments at pH 10.5 and 11.0 were found to have no effect on myofibrillar protein hydrophobicity which was found to be similar to that of raw meat protein, indicating that the proteins retained the native conformation. SDS-PAGE of extracted proteins showed greater amounts of myosin heavy chain relative to raw meat. Emulsification capacity showed relatively little change for samples with different extraction pH values, although it was significantly higher for pH 11.0. The foam expansion property of myofibrillar proteins increased significantly with extraction pH values, and obtained a maximum value at pH 11.5. The proteins extracted at pH 10.5 and 11.0, to some extent, could regain their original conformation after pH readjustment to 6.2. The functionality of the recovered protein suggests that this may provide an opportunity for greater utilization of dark poultry meat.