As you read in the discussion of molecular gastronomy , chefs at the forefront of modern cuisine are exploring and inventing new techniques in food preparation and presentation. One category of new techniques is the use of nontraditional thickeners or binding agents for sauces.
Hydrocolloids
A colloid is a mixture in which one substance (called the dispersed phase ) is evenly mixed throughout another substance (called the continuous phase ). Many colloids are familiar to us. Milk, for example, is liquid water in which milk solids and tiny butterfat globules are evenly mixed. Foams are colloids in which air bubbles are evenly distributed throughout a liquid. Smoke is a colloid of soot particles mixed in air. Emulsions such as mayonnaise are familiar colloids from the kitchen.
A hydrocolloid is a colloid in which the continuous phase is water. The presence of particles mixed throughout the water changes the water’s characteristics. For example, gelatin is a hydrocolloid familiar to all chefs. In this product, strands of proteins are mixed in water. Because these strands bind to each other, even a small amount of gelatin is enough to turn water from a liquid to a soft solid, called a gel. Another familiar example of a hydrocolloid is a sauce thickened with starch. The strands of starch change the water base from a thin liquid to a thicker one.
When chefs who practice molecular gastronomy use the word hydrocolloid to describe unusual thickeners and jelling agents, such as sodium alginate and other gums, it makes them sound especially scientific and mysterious. But remember, chefs have been using hydrocolloids their entire careers. They just haven’t called them that.