Thickening Agents: Oils

Sauces can also be thickened without heat by increasing the presence of fat droplets, which are bulky and more slow-moving than water molecules. Cream and milk act as thickeners because of their fat content. Water and oil do not mix, so sauces thickened like this require an emulsifier (see emulsion). Common emulsifiers are the lecithin in egg yolks, denatured proteins like gelatine, or ground animal or plant tissue, which contains an abundant quantity of emulsifying phospholipids. These sauces also require precise proportions of fat and water to remain stable.