I cracked open a can of Doan’s Craft Brewing Rye Stout the other day, and asked my wife Stephanie if she wanted a glass. I poured some out so she could taste it, and it was definitely not the right fit at the time, specifically because it was too bitter. She normally likes bitter beers, particularly those with huge hop presence. Doan’s Rye Stout is not the most hop forward beer. This got me to thinking about the two different ways that bitterness can be imparted in a beer. The most common method, via the addition of hops during the boil phase of brewing, is the one I think most people are familiar with. But there’s a second method that often gets overlooked, and that is via roasted malts, contributing a bitterness similar to that of coffee.
So what’s the difference? Let’s look at how each type of bitterness occurs in the first place.
Hops are bitter because it is a benefit for a plant to be bitter; most toxic compounds in plants are bitter. As a result, herbivores and omnivores learned to avoid anything with bitter flavours. When it comes to plants that aren’t toxic, over the millennia, evolution has selected for plants containing bitter flavours, as they trick animals into avoiding them!
Humans evolved with this same response, and as every craft beer fan has likely experienced, many people still don’t enjoy any bitterness in food or beverages, particular us North Americans with our sugar filled, ultra-processed foods. It turns out that this is to our great detriment, as consuming food or beverages with bitter compounds triggers a cascade of positive effects on our digestive system.
In malts, the bitterness is not contained within the grain itself. In fact, the barley that is used has been selectively bred over the years to lack bitterness, and instead be chock full of sugars and starches. So how does it get bitter? Browning. The Maillard reaction, responsible for the browning of food during cooking is also responsible for the majority of a beer’s colour and flavour. This browning process releases hundreds of aromatic compounds, many of which contribute aromas like caramel, bread, toast, chocolate, or coffee. Browning also creates odourless compounds called melanoidins, and these are what contribute bitterness and roasted/burnt flavours to beers containing heavily roasted malts.
In terms of flavour differences, you will pick up most of the difference via referential cues. If a beer contains a large amount of aromatic hop compounds, your brain’s conclusion will be that the bitterness is contributed by hops. If a beer contains a lot of Maillard based aromatic compounds, your brain will conclude that the bitterness is from roasted malts. At the end of the day, if you were to isolate bitter melanoidins and hop alpha acids, stripped free of their aromatic counterparts, and ran a blind taste test, you probably wouldn’t be able to tell the difference. Useful right? But at least now you can be *that person* at the next bottle share.
Image credit: GolemXIV via Wikipedia.org