Desem (Dutch for "leaven") is a type of sourdough starter made from whole wheat, spelt or other flours (amaranth or kamut) and water, inoculated by wild yeasts and bacteria, traditionally used in Belgium to make healthy, nutrient-rich bread. The starter is grown in a bed of flour at cool temperatures until it reaches sufficient maturity. The term "desem" also describes the loaf made with this starter.