Biochemical and physicochemical properties of thermally treated natural actomyosin extracted from normal and PSE pork Longissimus muscle

Biochemical and physicochemical properties of thermally treated natural actomyosin (NAM) from normal and pale, soft and exudative (PSE) pork were studied. About 37% and 25% of available sulphydryl groups formed disulphide bonds or other permanent chemical bonds at 70 degrees C in NAM from normal and PSE pork, respectively. Surface hydrophobicities of NAM from normal and PSE pork at 70 degrees C were 3.6 and 2.4 times greater than that at 40 degrees C. About 90% of the alpha-helical structure of NAM was lost by heating to 70 degrees C. The temperature at maximum alpha-helical content decline of NAM was in accordance with the peak 3 thermal transition obtained by differential scanning calorimetry and the lowest storage modulus (G') during thermal rheology. NAM from normal pork underwent aggregation with a higher extent of hydrophobic interaction and disulphide bonds, higher temperatures at maximum velocity for conformational change and unfolding than that from PSE pork. As a consequence, NAM from normal pork had superior theological properties. (C) 2008 Elsevier Ltd. All rights reserved.