Thickening – Potatoes

Thickening sauces and soups can be accomplished by a variety of ingredients but most rely on a starch. Even though starches such as flour and potatoes are mostly carbohydrate, they also have proteins that, when heated, interact with liquid to thicken them. Most cream soups begin with a roux and milk. With chowder, it is primarily the potatoes that act as the thickening agent.

Russets or long white potatoes work best because of the higher starch content. These potatoes also don't hold together as well when heated and, as they breakdown, make for a thicker soup.