Gel electrophoresis, phase microscopy and water-holding capacity studies of beef sternomandibularis muscle treated with sodium chloride and alkaline phosphates
Beef sternomandibularis muscle (STM) was treated with various concentrations (0.10M, 0.40M, 0.70M and 1.0M) of sodium chloride (NaCl), with and without 10mM pyrophosphate (PP), and differences in myofibril swelling, myofibrillar protein extraction and water-holding capacity (WHC) were evaluated. As NaCl concentration increased, swelling of isolated myofibrils increased and reached a maximum at 1.0M NaCl. However, in the presence of 10mM PP, the NaCl concentration required to achieve maximal swelling was reduced to 0.70M NaCl;Results of gel electrophoresis revealed that as the NaCl concentration increased from 0.10M to 1.0M, the extraction of titin, myosin and other myofibrillar proteins from beef STM also increased. Furthermore, the addition of 10mM PP to NaCl solutions enhanced the extraction of myofibrillar proteins, particularly titin, from beef STM. Beef tissue WHC was increased by higher NaCl concentrations and the combination of NaCl and 10mM PP produced higher WHC values than NaCl alone;In the second study, the effects of NaCl, NaCl + 10mM PP, NaCl + 10mM tripolyphosphate (TPP) and NaCl + 10mM sodium polyphosphate glassy (SPG) were examined by treating beef STM with various concentrations (0.30M, 0.47M, 0.64M and 0.80M) of NaCl, with and without the presence of 10mM PP, 10mM TPP or 10mM SPG. Beef myofibril swelling was greater when phosphates, especially PP and TPP, were combined in solution with NaCl than when only NaCl was used;Gel electrophoresis showed that increased NaCl concentrations resulted in increased extraction of titin and myosin from beef STM. Additionally, the WHC of beef STM increased as NaCl concentration increased and the WHC was further increased when 10mM phosphates, particularly PP and TPP, were combined with NaCl. The increased beef myofibril swelling and increased beef STM tissue WHC observed in both studies was attributed to the increased extraction of a critical amount of myofibrillar/cytoskeletal protein, or to the increased extraction of a critical type of myofibrillar/cytoskeletal protein, namely titin.