Fat

Fat is not filler. It carries the fat-soluble flavour compounds, it gives cured meat its melt and its mouthfeel, and in a ground product it holds the whole structure together. Good charcuterie fat is firm fat, which is why hard pork back fat, the dense dorsal fat off the pig's back, is prized over soft belly or the greasy intermuscular fat. That firmness comes from a higher proportion of saturated fat, so the pig's breed, its diet and the cut all show up in how the fat behaves.

The ratio of lean to fat is one of the defining choices in a recipe. Too little fat and the product dries hard and eats dry; too much and it turns greasy, slow to dry and prone to a rendered, oily surface. A common working range for dry sausage is roughly a fifth to a third fat, though it varies widely by tradition and product, and whole-muscle cures rely on the fat cap and marbling already in the cut rather than on any added fat.

Fat's enemy is heat at the grinder. Warm, soft fat smears rather than cutting cleanly, coating the lean in a film that blocks bind and blocks drying, the fault known as fat-smearing. The defences are simple: keep the fat cold or part-frozen, keep blades and plates sharp, and work quickly. Over the longer life of a cure, fat is also where rancidity begins, since it is the fat that oxidises, so fat quality and how the finished product is stored decide how well the flavour holds.