When you don't cover yeast dough while it rises, several things can happen that may affect the outcome of your bread or baked goods:
Drying out: Yeast dough contains moisture, and when left uncovered, the dough's surface can dry out. This can lead to the formation of a dry crust, which may impede the dough's expansion during rising.
Crust formation: Without a cover, the surface of the dough may develop a thin, dry crust. While this might not be detrimental to the rising process, it can lead to difficulties when shaping the dough later on.
Slower rising: Covering the dough helps create a warm and moist environment, which is optimal for yeast activity. When left uncovered, the dough might rise more slowly since the moisture on the surface evaporates, slowing down the fermentation process.
Reduced volume: Yeast dough needs to expand during rising, and without proper covering, the surface tension of the dough may dry out and prevent it from achieving its full volume potential.
Off flavors: If the dough dries out too much, it can form a tougher outer layer that may not allow for proper gas exchange during fermentation. This can potentially lead to off-flavors in the finished product.
To ensure a successful rise and better bread or baked goods, it's generally recommended to cover yeast dough while it proofs. You can use a damp cloth, plastic wrap, or a damp kitchen towel to cover the dough and maintain the necessary moisture during fermentation. Additionally, placing the dough in a warm, draft-free area will also aid in proper rising.