Autolyzed yeast (AY) is an ingredient that comes from the breakdown of the yeast Saccharomyces cervisiae, also known as Baker's yeast. It is a food additive used to improve the flavor and nutritional value of many food and bakery products.
Eggs, according to multiple sources, have a great ability to leaven or puff up foods when air is beaten into them,2, 3 and that they aid in leavening overall in baking applications. Whole eggs and yolks can also trap and hold air that expands during heating, leavening cake batters and other baked goods.