Caffeine is a key component of coffee. As the coffee cherries grow, it acts as a natural repellent against insects, and, once the beans have been roasted, ground, and brewed, offers stimulating effects that make it a favorite pick-me-up for millions around the world.
The caffeine content of a single cup of coffee varies depending on a number of factors, such as variety, growing conditions, and brewing method. For example, the average espresso contains around 60 mg of caffeine, compared to an estimated 96 mg for filter coffee.
However, one of the common misconceptions that continues to exist around caffeine and coffee is the influence of roasting. While some believe that the bitter taste of dark roasts indicates higher caffeine levels, others suggest that roasting “burns off” caffeine molecules.
To understand the differences between caffeine content in light and dark roasts, I spoke with the owner of Hoccino Coffees, Bruno Danese.
What is a “light” and “dark” roast?
“Light”, “medium”, and “dark” are broad terms used to describe the roast profile of coffee beans.
During roasting, decomposition of chlorophyll changes the bean colour from green to yellow. As the roast progresses, chemical reaction continues to deepen the bean colour, from yellow to increasingly darker shades of brown.
Thus, the terms light, medium, and dark indicate the development of the beans, offering a rough idea of the stage at which they were dropped from the roaster. The ambiguity of the terms, however, means that what seems like a light roast to one person, may be a medium roast to another.
To better distinguish roast profiles, the colour of the beans are often used in conjunction with other factors, including size, weight, moisture content, and characteristics, such as acidity and mouthfeel.
Bruno is the owner of Hoccino Coffees, a café and roastery based in Obihiro, Japan. He tells me that, for him, light and dark roasts can be determined by three main measurements: roasting time, end temperature (or drop temperature), and flavour profile.
“Light roasts will be roasted for a shorter period of time and will usually have a much lower drop temperature than dark roasts,” he explains. “Light roasts, if roasted well, tend to highlight its acidity and preserve more of the origin’s traits – so you can accentuate what the coffee actually tastes like.”
The presence of oils on the surface of the beans is another useful indicator of roast profile.
This is because, as a roast goes on and the outer layer of the beans become more porous, causing oils deep within the beans’ structures to gradually migrate to the surface. The longer the roast lasts, the more oils appear. Therefore, dark roasts tend to be oilier than light roasts.
How does roast profile affect caffeine content?
Caffeine is present, to varying degrees, in all arabica and robusta coffee varieties. In green beans, it accounts for approximately 1% of the total weight, contributing much of the coffee’s bitterness and stimulating properties.
Despite a widespread belief that caffeine levels change when beans are roasted, Bruno tells me that this is actually a misconception.
“The amount of caffeine per coffee bean does not change regardless of whether it’s light or dark roasted,” he says.
“The difference in caffeine content comes into play when you move from roasting to measuring. Basically, it depends on whether you measure coffee by weight or by volume.”
The reason for this is that during a roast, the size and weight of the beans alter considerably.
The longer they are exposed to heat in the roasting chamber, the more they lose moisture content and the lighter in weight they become.
According to some estimates, roasting until the beans are dark and oily can cause the coffee to shrink by more than 20%. At the same time, bean size increases.
Therefore, if you prepare coffee by weighing the beans, you will get more caffeine from a dark roast because more beans are used to make up the desired weight.
On the other hand, if you measure by scoop (or volume), dark roasted coffee will have lower caffeine because fewer beans are contained in a scoop due to their larger size.
But that’s not all – Bruno explains that it also comes down to the solubility of the beans.
“Dark roasted coffee is more soluble than light roasted coffee,” he says, “which means it’s easier to extract flavours, caffeine, and other compounds from the coffee. So, extraction yield tends to be higher with dark roasts – but caffeine content stays the same.”
Packaging for light and dark roasts
Sometimes, coffee roasters may choose to have distinct packaging designs for their product based on the roast profile of the coffee. Bruno says that the need to do so would depend on the concept of the business.
“For me, I don’t need it at my cafe because most of my coffee is roasted within a similar range,” he tells me, “so I don’t need to identify them and my customers know what they are buying since they expect the roast level to be very similar.
“But if you offer coffee at a wide range of roast profiles, I think it would be interesting to have different packaging. Having said that, we do offer a dark roast coffee that goes in a separate packaging.”
One of the most common and effective ways to organise different roast profiles is with the use of colours. For example, Starbucks’ dark roast comes in a purplish-black packaging, while their blonde roast (lightly roasted beans) comes in gold-toned packaging.
Bruno says that roasters may also consider using packaging design to inform customers about the differences between roast profiles.
“On the bag of our dark roast coffee, we include an explanation on the differences between dark and light roast,” he says. “We’re always trying to offer some educational content for our consumers – that is important for us.”
Furthermore, if caffeine content is a concern for consumers, especially for those who are more sensitive to it, he makes sure to share his experience and knowledge to keep consumers informed.
Having said that, he says he’s not likely to over-emphasise caffeine content on the packaging because “coffee offers much more than just caffeine”.
While caffeine is a stable compound, flavour and aroma in roasted coffee are extremely sensitive to external factors, such as oxygen, moisture, and heat.
Therefore, it is of utmost importance to protect coffee, whether light roast or dark roast, with quality packaging.
At MTPak Coffee, we offer a range of sustainable packaging for specialty coffee roasters. Our coffee pouches are fully customisable and you can choose from a variety of features including packaging design, resealable zippers, degassing valve and more.
With our high-quality bags, your coffee will remain fresh for longer and your customers can enjoy all of its unique characteristics.