Have you ever taken a sip of beer and thought, this smells like chocolate - but then checked the label and saw no mention of actual cocoa? You’re not imagining things. Many dark beers, particularly stouts and porters, have rich, chocolatey aromas even though they don’t contain any chocolate.
So what’s going on? The answer lies in the magic of malt, heat, and brewing science.
If you’re curious about the science behind beer flavours and want to take your knowledge further, check out our WSET beer qualifications. At the end of our beer courses, you’ll gain a globally recognised qualification.
Malt: the backbone of chocolate aromas
Beer gets its colour and many of its aromas from malted grains – mainly barley – that has been soaked, germinated, and then dried in a kiln. The temperature and length of time used during kilning determine the final colour and flavour of the malt.
Malt can be broadly divided into two categories: base malts and specialty malts. Base malts are lightly kilned and provide the foundation of a beer’s body and fermentable sugars, contributing subtle aromas like bread, crackers, and light honey. Specialty malts, on the other hand, undergo a higher degree of kilning or roasting to develop deeper, more intense aromas, ranging from toasted nuts and caramel to coffee and chocolate.
The role of dark roasted malts
The chocolatey notes in stout come from dark roasted malts – malted barley that has been roasted at very high temperatures to bring out bold flavours. These malts are not dissimilar to coffee beans or cocoa beans, which develop their complex flavours through roasting.
Chocolate malt and black malt are both significant contributors to the chocolate-like aromas found in stout, but they also bring additional roasted characteristics. Named for its deep brown colour, chocolate malt delivers rich cocoa notes, but it can also introduce coffee and toasted aromas depending on how it is used. Black malt is roasted even darker, contributing bolder coffee and burnt toast notes alongside hints of dark chocolate. Roasted barley, an unmalted grain roasted at high temperatures, is distinct from these malts and is a key ingredient in Irish stout. It creates an even stronger espresso-like bitterness, adding a dry, roasted edge that defines the style.
These malts do more than just impact flavour – they are also responsible for the deep brown-to-black colour that defines the stout style.
The Maillard reaction: the secret to stout’s flavour
Ever wondered why toasted bread, seared steak, roasted coffee, and dark beer share similar rich aromas? That’s thanks to the Maillard reaction – a chemical process that occurs when amino acids (proteins) and sugars interact under high heat. This reaction is responsible for many of the deep, caramelised aromas we associate with cooked foods, from the golden crust of freshly baked bread to the roasted notes in coffee beans.
During the malting process, the Maillard reaction plays a crucial role in shaping the final character of dark beers. Temperature, time, and moisture levels all influence how this reaction unfolds. High temperatures, combined with controlled moisture levels, allow the process to develop hundreds of complex aroma compounds, many of which contribute to the chocolate, caramel, and coffee-like notes found in stout. The longer and hotter the roasting process, the deeper and more intense these flavours become.
Other factors that enhance chocolatey perception
While malt is the primary source of chocolate-like aromas in stout, other brewing techniques can further enhance the effect. Yeast esters, for example, can add subtle fruity aromas that complement the chocolate and roasted malt character.
How a stout is served can also influence how we perceive its flavour. Many stouts, particularly Irish stout, are nitrogenated – meaning they are infused with nitrogen gas in addition to carbon dioxide (CO₂). The key difference is that nitrogen bubbles are much smaller than CO₂ bubbles, creating a smoother, creamier texture with a thick, velvety foam.
This creamy mouthfeel helps to soften the perception of bitterness, making the beer feel rounder and more balanced. Think of the difference between black coffee and one with steamed milk. The milk doesn’t necessarily add sweetness but changes the texture, reducing the harshness of the coffee’s bitterness. In the same way, nitrogen in stout blunts the intensity of roasted bitterness, allowing the chocolatey malt flavours to come through more smoothly.
Barrel ageing can also introduce additional layers of flavour. When aged in bourbon barrels, for example, a stout can develop notes of vanilla, caramel, and coconut, which complement the chocolatey malt character already present in the beer.
Classic stout styles with chocolatey notes
Different stout styles showcase chocolate aromas in their own way. Irish stout, known for its roasted coffee and dark chocolate notes, owes much of its flavour to the use of roasted barley. Oatmeal stout, brewed with a portion of oats, has a silky texture that makes the chocolate-like character feel richer and smoother. Milk stout, sometimes called sweet stout, contains lactose – an unfermentable milk sugar that enhances residual sweetness and brings out chocolate and caramel flavours. Imperial stout takes things up a notch with high alcohol content and intense malt complexity, often displaying pronounced dark chocolate and dried fruit characteristics.
Next time you sip a stout...
Next time you pour a dark, rich stout and catch that unmistakable whiff of chocolate, you’ll know it’s not from added cocoa – it’s all in the malt and brewing procedures.
Want to test it for yourself? Try tasting a classic Irish stout, an oatmeal stout, and an imperial stout side by side and see how the chocolatey notes differ. Cheers!
Whether you’re just starting out or already know your porters from your stouts, our courses are designed to empower you with the knowledge and skills to navigate the world of beer. From professionals looking to sharpen their skills to enthusiasts eager to dive deeper, our courses equip students with the skills to evaluate, describe, and recommend beer with clarity and confidence. Find your nearest course provider now.
This blog post was written by Josh Beamish, Digital Marketing Manager at WSET and a WSET Diploma student. A longtime fan of Australian wine and Italian Nebbiolo, his holidays often revolve around visiting wine regions. When he's not exploring the world of wine, he enjoys craft beer and a perfectly balanced Negroni.
