The study was undertaken to determine the physico-chemical properties of proteins isolated from mechanically separated turkey meat (MSTM) by a pH-shifting technique. The effect of four pH values (2.5, 3.5, 10.5 and 11.5) was investigated. Protein yield did not show any statistical difference between the extractions carried out at pH 2.5, 10.5 and 11.5. However, yield was considerably lower when pH of extraction was 3.5 (P = 0.0097). Total protein extractability and myofibrillar protein hydrophobicity showed the same pattern, with the highest values at pH 10.5 and the lowest at pH 2.5. No significant (P>0.05) differences were found between the various pH of extractions on total, neutral and polar lipids, which on average were equal to 92.3%, 93.0% and 90.7%, respectively. TBARs analysis showed no difference between acid and alkaline treatments; however, the values were significantly lower compared to raw MSTM (P < 0.0001). SDS-PAGE analysis showed a greater concentration of myosin heavy chain and actin in protein isolates compared to raw MSTM. Amino acid analysis of isolates showed higher concentration of glutamic acid and reduced levels of histidine and methionine compared to raw MSTM. Uronic acid and hydroxyproline analysis revealed that most of the proteoglycans and collagen were deposited in the sediment fraction obtained during the centrifugation step following protein solubilization. (C) 2010 Elsevier Ltd. All rights reserved.