The salinity of the brine solution varies from 5% to 10% depending on whether the fish to be salted is lean or oily. The immersion time also varies, depending on the thickness of the fillet, but is around 15 to 20 minutes. Afterwards, it is necessary to desalt the fish for 10 minutes, by soaking in fresh water.
Next, the fillet is vacuum packed, with some oil or butter and seasonings. It is then cooked in a water bath, first at 83°C, then at 56°C. The juices (cellular water and the products of collagen hydrolysis and protein coagulation) given off by the fish during cooking can be reabsorbed into the fillet thanks to the elasticity preserved by the actin and myosin. As a result the fillet gains in flavour and texture. This reabsorption is made possible by lowering the temperature of the product to less than 10°C in less than two hours using a graduated cooling process in 3 steps: room temperature, 18°C and in water with ice.
The fillet, in its vacuum packaging, can then be stored in a cool place before being reheated at the moment of serving.