Lipid Oxidation
Also known as Autooxidative phenomena, Of cholesterol, Of phospholipids, Off-flavor, Polyphenols, Protein oxidation, Tocopherols, Vitamin-E, Warmed-Over-Flavor, Oxidation, Autooxidation, Autoxidation, Lipid autoxidation
The spoilage of fat by oxygen, the chemistry of rancidity. Unsaturated fats react with air to form the stale, painty off flavours that ruin a cure, which is why fat quality and oxygen control matter.
Lipid oxidation is the slow burning of fat by oxygen, and it is the chemistry behind rancidity. The unsaturated fats in meat react with air to form peroxides, which break down into the aldehydes and ketones that taste and smell stale, painty or cardboard-like. It is the most common way a well-made cure goes wrong over time.
Several things speed it: soft, already-oxidised fat from a poorly finished animal, exposure to air and light, warmth, and salt, which is mildly pro-oxidant. This is why Meat Quality insists on firm, fresh fat, and why the choices around fat are not only about texture but about how long the product will keep.
The curesmith's defences are largely about denying oxygen and adding antioxidants. The noble mould coat shades the surface, vacuum packing removes air, and ascorbate and many spices are antioxidant. The same process, run backwards, is why those tools exist.
Autooxidation is the engine of rancidity. Once a free radical forms on an unsaturated fat, it reacts with oxygen and then attacks the next fat molecule, making a new radical, so the reaction feeds itself and accelerates. It runs faster with more unsaturated fat, more oxygen, warmth, light and traces of iron or copper. The whole defence against rancidity, antioxidants, cure, vacuum, cool and dark, is really about interrupting this one chain.
Temple element. Pillar, Meat Quality