Salt removes moisture from food primarily through a process called osmosis.
Understanding Osmosis
Adding salt to food creates a higher concentration of salt on the food's surface compared to the inside. Water naturally moves from areas of low solute concentration (less salt) to areas of high solute concentration (more salt) to equalize the concentration. This movement of water is osmosis. The water within the food cells moves outward, towards the higher salt concentration, resulting in a drier food surface. [Adding salt to food triggers a process of osmosis, which causes water to flow from an environment with a low salt concentration to one with a higher concentration. In this way, salt removes water from food, inhibiting the growth of micro-organisms.](Reference 1 & 7)
The Extent of Moisture Removal
It's crucial to note that the amount of moisture removed by salt varies. While salt does draw out moisture, it's not always a significant amount, depending on factors like the type of food, the amount of salt used, and the duration of contact. [However, salt does not create this moisture loss to a considerable degree in many cases. Roasts, for instance, may be salted before cooking if…](Reference 2) For example, a small amount of salt sprinkled on a roast may not considerably dry it out.
Practical Applications and Examples
- Preservation: Salt's ability to draw out moisture is a key mechanism in food preservation. By dehydrating the food surface, it inhibits the growth of microorganisms responsible for spoilage.
- Curing: In techniques like curing meat, a controlled amount of salt is used to draw out moisture, and salt also contributes to flavor development.
- Surface Drying: Salting food before cooking can create a slightly drier surface, which can help in browning and crisping. [If you put salt on food, you create an area on the surface of the food that water likes to stick to. So the water molecules moving around near…](Reference 3)
Contrasting Brining
It's important to differentiate this effect from brining. Brining involves submerging food in a saltwater solution. In this case, the food absorbs water, rather than losing it, resulting in moister food after cooking. [So if you put a 100gr piece of meat in saltwater it will absorb about 10g of water. It will leave the meat salty, but more tender.](Reference 4)
The "Salt Pulling Moisture" Misconception
While the image of salt "pulling" moisture is a common way to describe the process, it's more accurate to say that salt creates a concentration gradient that causes water to move. The water is already there; the salt simply facilitates its movement. [The salt only pulls out a small amount of moisture and other proteins. Then when you do a reverse-sear the proteins form a crust that then seals…](Reference 5)
