Until 1817, porter was a brown beer, as amber and brown malt were the easiest and cheapest available brewing grains. It was then that Daniel Wheeler invented a method to create “patent malt,” black, roasted, malted barley that could be used in small quantity to get the desired color in porter and stout without using as much of the harsher brown malt.
Pale malt was also becoming more available, and porter and stout recipes began to reflect this. In Dublin, brewers used grist of pale and patent malt only, whereas in London, brewers kept a good measure of brown and amber malt in the grist. The latter made for more complex, less-attenuated ale, a recipe that approximates all of today’s stouts outside of Ireland.
These brews were heavily exported, the strongest of them favored by the Imperial Court of the Russian Czar (it is believed that Catherine the Great fell in love with strong stouts on a trip to England in the late 1700s). Barclay Perkins, a porter brewer from London, had by this time established itself as a major player in the export of porter and stout into the Baltic regions, virtually monopolizing the Russian market. It was Barclay Perkins’ strongest stout that was sold to the Imperial Court, and gave birth to the style known as imperial stout.
Between the base of pale malt and roast, brewers use nearly every type of brewing and specialty malt to add body, flavour and aroma as they see fit. Munich, caramel and chocolate malts are commonly used to create a dessert-like brew, with notes of bittersweet chocolate, dark dried fruit, coffee, liquorice and burnt sugar in the flavour and aroma. High protein grains like oatmeal, rye and wheat may be used to add a bit of smoothness and head retention. A creamy, hearty mouthfeel and fullness are key to offsetting the high alcohol content, usually well upward of 9% abv. Imperial stout should be neither too dense, nor too thin.
Hop profile can vary widely, and American version otherwise style tend to be noticeably more bitter than English examples. A stiff dose of bittering hops can complement the roasted edge rather than take it overboard.
If it is truly an American version you want, showcasing that aggressive, resinous Northwestern hops character, then try Stone’s Imperial Russian Stout. In fact, there are so many stellar examples that it is hard to choose, but insanely fun to explore. Most hold up well over the long haul, so cellaring only makes the variety even more stunning.
To many, imperial stout is the absolute apex of the brewing arts, and unlike a lot of coveted brews, examples are usually lurking about nearby.