Baker's Purchase is a term used in the baking industry to refer to the purchase of ingredients such as YEAST, flour, sugar, and other items necessary for baking. YEAST is one of the most important ingredients in baking, as it helps dough rise and gives baked goods their desired texture. YEAST is a single-celled organism that is available in both dry and liquid forms. It is often sold in small packages or jars and can be stored in a cool, dry place for up to two years.