The extraction of soluble proteins aids salt swelling of pork meat

Abstract

The salt-induced swelling of meat is an important phenomenon in meat processing. Existing theories of the mechanism of fluid uptake by meat in NaCl solutions focus on myofibrillar proteins, especially myosin, but the role of sarcoplasmic proteins in salt swelling is unclear. This study clarifies the role of these soluble proteins. Experiments on the weight gain of blocks of porcine longissimus muscle show that multiple changes of fresh saline result in greater swelling and that enclosing meat blocks in dialysis tubing to reduce egress of soluble proteins decreases swelling over a 7-day period, compared to muscle blocks simply suspended in an excess of 3% NaCl. A hypothesis is presented that explains these findings, by proposing that sarcoplasmic proteins, which carry a net positive charge at rigor pH, balance out the Donnan osmotic effect of the myofibrillar proteins actin and myosin, which are reported to carry a net negative charge at the rigor pH of pork meat in the presence of salt. This hypothesis also explains why sarcoplasmic protein denaturation/precipitation may affect the weight uptake in salt-treated meat.

Keywords

• myofibrillar proteins
• saarcoplasmic proteins
• water-holding
• mechanism of swelling