Muscle Structure

Meat is roughly three quarters water, a fifth protein and the rest fat and minerals, and almost everything a curer does is an argument with that water and those proteins.

The structure is nested. Muscle fibres are long cells, bundled into groups, and each level is wrapped in a sheath of connective tissue. Inside the fibres are the myofibrils, and inside those the contractile proteins, actin and myosin. The water sits mostly within and between the myofibrils, held there by the protein structure rather than pooled loosely, which is why fresh meat feels moist rather than wet.

The proteins fall into three groups that behave completely differently, and this is the distinction worth carrying. The myofibrillar proteins, chiefly myosin, dissolve in salty water and are the ones that matter for binding: extract them and they set into the matrix that holds a sausage together. The sarcoplasmic proteins are water-soluble, live in the fluid between the myofibrils, and include the enzymes and the pigment myoglobin. The stromal proteins are the connective tissue, mainly collagen, and they dissolve in neither, which is why gristle stays gristle in a raw cured product and only becomes gelatin under long moist heat.

That last point decides how cuts are chosen. A working muscle carries more collagen and more myoglobin, so it is darker and tougher and better suited to slow cooking or fine grinding; a supporting muscle like the loin is pale and tender and has little of either. Neither is better, but a cut used for the wrong job disappoints predictably: collagen in a dry-cured salame stays as chewy threads, since nothing in that process ever converts it.

Water-holding capacity is the property that governs yield and texture, and it depends on pH. Meat is at its least able to hold water near pH 5.2, close to where normal pork settles after slaughter, and both salt and higher pH improve it. This is the mechanism behind two familiar faults: PSE meat, which has dropped its pH too fast while still warm, is pale and leaks badly and makes poor cured products; DFD meat, which never dropped far enough because the animal was stressed and depleted, is dark, sticky and high in pH, holds water well but spoils faster and is the wrong material for a long cure.

Fat structure matters as much as fat quantity. Fat in firm, saturated sheets, such as pork back fat, cuts cleanly and stays as distinct particles in a slice. Soft, oily fat smears at the grinder, coats the lean and blocks the bind. The difference is chemistry rather than handling, which is why fat is selected rather than merely trimmed.