Coffee is a staple beverage for millions of people worldwide, consumed in endless scenarios: catching up with a friend, powering through an intense study session, or simply kickstarting the day.
From the classic drip coffee and trendy cold brew to the precision of the French press and the intensity of espresso, there are countless ways to make the perfect cup of joe. The key difference between each brewing method is how the water interacts with the coffee grounds and the time it takes to brew.
Drip coffee involves hot water slowly passing through ground coffee beans, while French press requires steeping the grounds in hot water before pressing them through a filter. Espresso machines work by forcing water through finely ground beans at high pressure, creating a concentrated shot. Pour-over coffee takes the drip method up a notch, offering better control over the brewing process, while cold brew involves steeping grounds in cold water for an extended period, resulting in a smooth, low-acid brew. Last but not least is instant coffee, which is made by drying roasted coffee into a powder or crystals. Instant coffee is the quickest and easiest alternative; all you have to do is pour hot water over the powder—and voilà , a ready-to-drink cup of coffee.
But behind that comforting cup lies an intricate world of chemistry, one that not only affects flavor but also introduces potentially controversial compounds like acrylamide.
So, what exactly is acrylamide, and should we be concerned?
Acrylamide is an organic compound (C₃H₅NO) formed primarily through the Maillard reaction, a chemical reaction between amino acids and reducing sugars that occurs when foods are heated above 120°C. In addition to giving many foods their browning and flavor, this reaction also produces acrylamide, particularly when the amino acid asparagine is present. Acrylamide is found in baked goods, fried foods, and coffee.
In the case of coffee, roasting the beans at high temperatures causes the asparagine present to react with sugars, forming acrylamide. The process of making instant coffee concentrates acrylamide even further. Because instant coffee is brewed and then dehydrated (by freeze-drying or spray-drying), this water-soluble compound becomes more concentrated in the final product.
Studies have shown that instant coffee can contain up to twice the acrylamide levels found in regular brewed coffee. High doses of acrylamide may be carcinogenic according to animal studies, prompting organizations like the International Agency for Research on Cancer (IARC) to classify it as a "probable human carcinogen."
But before throwing out that jar of instant coffee, it’s important to understand the context and numbers.
While some toxicology studies on animals have shown that large doses of acrylamide can cause cancer, the key phrase here is large doses. The levels of acrylamide that humans typically consume in a normal diet are far lower than those used in animal studies. The acceptable daily intake of acrylamide varies between agencies (from 25 to 195 micrograms) and is primarily based on guesses. Health Canada has estimated that the average adult consumes between 0.3 and 0.4 micrograms of acrylamide per kilogram of body weight per day.
So how much coffee would you need to drink before acrylamide becomes a problem? Let's do the math. A cup of instant coffee contains roughly 10 micrograms of acrylamide per liter. To reach the lower bound of the most conservative acrylamide exposure recommendations (about 25 micrograms per day), you'd need to drink around 2.5 liters of coffee—about 10 cups. For most people, that's an absurd amount of coffee to consume in a single day, meaning that the occasional cup of instant coffee is unlikely to pose a serious health risk.
It is also important to note that extrapolating data from toxicological studies in rodents to assess the health implications of acrylamide in humans may not be entirely accurate—after all, we are not rodents. Human epidemiological research has shown a general lack of association between exposure to dietary acrylamide and the incidence of different types of cancer.
And if you need yet another reason to hold onto your beloved coffee, I recommend reading this article on the many health benefits linked to moderate coffee consumption.
With so many types of coffee and so many factors at play, one might wonder: which is the best type of coffee to drink? For me, instant coffee is the go-to! Many dismiss it as inferior, but it has its merits. It’s quick, easy, and affordable, which is ideal for the average university student. The slight increase in acrylamide might seem like a downside, but as long as it's consumed in moderation, there's no real cause for concern. As Paracelsus wisely said (and Dr. Joe Schwarcz constantly reminds us), it's the dose that makes the poison.
Hosna Akhgary is a BSc candidate at ÎÛÎÛ²ÝÝ®ÊÓƵ University, majoring in Pharmacology.
Part of the OSS mandate is to foster science communication and critical thinking in our students and the public. We hope you enjoy these pieces from our Student Contributors and welcome any feedback you may have!
