In baking, the term proofing actually has two applications. With regards to yeast, which is a living organism that can weaken over time, it’s a process that is used to determine if the yeast is still active and capable of leavening bread dough. Proofing is also the term that is used to describe the second (or final) rise of a shaped yeast dough.
To proof yeast – Mix the yeast with warm water (between 105ºF and 110ºF) and allow it to sit for a few minutes. If the yeast becomes creamy and foamy, it is still active. If the yeast does not foam and become creamy it is no longer active and should be thrown out as it will not work properly in the dough.
To proof shaped dough – For the final rise of a shaped yeast dough simply place the dough in a warm, dark, draft free area and allow it to rest undisturbed. Many ovens today come equipped with a PROOF function and it works exceptionally well. If you have an oven that has this feature, take advantage of it when proofing dough.