The science of confit

Question

In recent weeks I have made both duck leg and pork belly confit with rich tasting and great texture results. I want to experiment with this technique further but to do so, and avoid wasting meat and fat, I'd like to understand the science behind the technique.

In particular what makes the result of confit so different to the result of braising for the same period at the same temperature?

Do different fats have different effects on the meat (other than the flavour they impart through the flavour of the oil). For example will a fat that is liquid at room temperature (olive oil etc) result in a different type of confit to cooking it in lard or duck fat?

What are the characteristics of meat that suit it to confiting? Is there a particular fat content or other factor that determines the success of this method?

Answer 1

The slow cooking give confit meat its texture and the storage time allows further reactions and dissolutions to take place. The traditional reason solid fats have been used for a confit is for preservation: once the fat cools it "seals" the meat. Today we can refrigerate, so many restaurants now make their confit with liquid oils.

Myhrvold has demonstrated that he can reproduce the duck confit by using a steam and air mixture to cook the duck leg and then flavor its surface with oil.

There are several processes competing when we heat meat to cook it:

• The collagen needs to melt and gelatinize. There are different types of collagen, each denaturing in different temperature ranges. As the meat is heated, collagen starts to shrink at about 40°C/ 104°F and by 80°C/176°F all of it is gelatinized. Different animals have different types of collagens and the right temperature could be anything between 60°C/140°F and 80°.
• The elastin, which exists in smaller quantities than collagen, will shrink with temperature and make the meat tougher.
• As the many molecules contract, they squeeze water from the meat, making it feel tougher.

So if you are going to develop a recipe, you will have to experiment. As a guide, the more collagen, the higher temperatures you will need. The amount of collagen goes up with the age of the animal and how much weight (stress) the muscle needs to support.

The reason confits are made by immersing the meat in oil may be that the oil makes it harder for the meat to loose its water, but I speculate.

Cooking for Geeks is one of the few places I found discussing the science of confit. Maybe Myhrvold's slim tome will have a section on it.

Answer 2

The low temp & long cooking will enable the enzymes in the product to work for a longer amount of time, therefore rendering the meat more tender. Look at McGee for more info about enzymes.