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Biochemical Properties of Natural Actomyosin Extracted from Normal and Pale, Soft, and Exudative Pork Loin After Frozen Storage
Author(s) -
Wang Haihong,
Pato Mary D.,
Shand Phyllis J.
Publication year - 2005
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.2005.tb07179.x
Subject(s) - chemistry , loin , food science , myosin , denaturation (fissile materials) , disulfide bond , water holding capacity , longissimus muscle , longissimus , myofibril , biochemistry , anatomy , zoology , biology , nuclear chemistry
The studies of natural actomyosin (NAM) extracted from normal and pale, soft, and exudative (PSE) pork longissimus muscle stored at ‐20°C for up to 6 mo, revealed that the surface hydrophobicity (S 0 ‐ANS) of NAM from PSE pork was significantly ( P < 0.05) higher than that from normal pork indicating greater conformational changes in proteins from PSE meat that resulted in the exposure of hydrophobic aromatic amino acid residues on the surface. Also, the S 0 ‐ANS of NAM was a function of storage time. The equations were as follows: S 0 ‐ANS = 16.9 × storage mo + 123 for normal and S 0 ‐ANS = 17.5 × storage mo + 164 for PSE. NAM from frozen normal pork had lower α‐helical content than comparable fresh pork. With extended frozen storage, viscosity of NAM from PSE meat was lower than that from normal pork. The sulfhydryl and disulfide contents were unchanged. Electrophoresis revealed an extra 95 to 100 kDa band from PSE meat NAM, possibly from α‐actinin or myosin degradation. Water‐binding capacity (WBC) of normal and PSE meat decreased with increasing storage time; however, there were only minor changes in thaw loss. The decrease of WBC of pork meat partially can be explained by the increase of S 0 ‐ANS observed for the NAM. These results suggest that proteins from PSE pork are more susceptible to denaturation and degradation in fresh meat and following frozen storage.