Beer is made from four basic ingredients - malted barley, hops, water and yeast. Anything else that finds its way into the brew pot is known as an adjunct. And almost everything has wound up in beer from milk to herbs and spices to animal blood to fruits and vegetables. Naturally, chocolate is a favorite adjunct of many brewers.
There are a few different ways to add chocolate to beer. Each will bring a different aspect of the cocoa bean to the beer.
Early in the brewing process, brewers mash the malted barley. Mashing is when hot water is used to excite enzymes in the grain to breakdown some of the starches and proteins in the barley kernel. Adding chocolate at this stage places it deep in the heart of the beer. Little flavor and even less aroma will translate into the pint glass but the chocolate will contribute a deep, earthy quality.
After mashing, the beer is boiled. This is when most chocolate beer brewers add their favorite adjunct. Beer is boiled anywhere from one to two hours. The earlier any ingredient is added the less of the more delicate aspects of that ingredient will be apparent in the beer. So, adding chocolate at the beginning of the boil is much like adding it to the mash. But when chocolate is added during the last fifteen minutes or so it will have a strong presence in the flavor and the aroma of the final beer.
To get the richest, most chocolaty taste in a beer, a brewer will add chocolate to the fermentation or conditioning tank, well after the boil. Chocolate added at this point will contribute huge chocolate aroma to the beer and a significantly chocolaty taste.
Young's Double Chocolate Stout is brewed by adding the chocolate during the boil. The chocolate aroma and flavor are apparent in the beer but not dominating. The chocolate aspect blends with the stout for a balanced, elegant beer.
Rogue Chocolate Stout, on the other hand, is brewed completely without chocolate. It is mashed, boiled and even fermented without touching any cocoa. Finally, chocolate is added in a secondary holding tank where it contributes all of its chocolaty goodness without having any of it boiled or fermented away. The result is a rich stout that tastes and smells as if someone crumbled a brownie into it - except without the soggy crumbs, of course.