New recommendations for measuring collagen solubility

The heat-solubility of intramuscular collagen is usually conducted in 1/4 Ringer's solution at pH7.4, despite this ionic strength and pH being inappropriate for post-rigor meat. The current work studied the percentage of soluble collagen and hydrothermal isometric tension characteristics of perimysial strips on bovine semitendinosus muscles in either 1/4 Ringer's solution, distilled water, PBS, or a solution of the same salt concentration as 1/4 Ringer's but at pH5.6. Values of % soluble collagen were lower at pH7.4 than 5.6. Increasing ionic strength reduced % soluble collagen. The maximum perimysial isometric tension was independent of the bathing medium, but the percent relaxation was higher at pH7.4 than at pH5.6, and increased with ionic strength of the media. It is recommended that future measurements of collagen solubility and tests on connective tissue components of post-rigor meat should be carried out in a solution of concentrations NaCl and KCl equivalent to those in 1/4 Ringer's, but at pH5.6, a pH relevant to post-rigor meat.