The main ingredients of a sausage are meat, fat, binding agents and water. There are three stages involved in preparing them: mincing the meat and fat, mixing the different ingredients together and filling.
Filing is where the mixture is put into the casing. Natural casings are the intestines of pigs, cows or lambs, and artificial casings can be synthetic or cellulose-based.
The fat is incorporated into the meat during mincing and mixing. To ensure consistency, the food-processing industry often uses milk or soya protein powder extract and eggs as binding agents. Alginates, a substance extracted from seaweed, are also excellent binding agents. Water plays a key role as a gelling agent in sausages. It is generally added during the mixing stage, in the form of ice.
Alongside the main ingredients, there are curing salts, such as sodium chloride or sodium nitrate, which play the same role as in other cured products. Sugar is also a common ingredient, incorporated in the form of sucrose or glucose.
Herbs and spices are key ingredients used as flavouring agents.
Fermented sausages are generally produced by introducing microorganisms in the form of lactic acid bacteria which trigger fermentation.