Does Roasting Coffee Beans Smell Bad?

Store-bought coffee beans can be a lifesaver. These offerings can make the process of making a cup of coffee much more accessible but still authentic and fresh enough not to be considered instant coffee.

However, when they roast them on-site or when you get home, you may notice that stinky smell. Why does it smell that way, and does roasting coffee beans smell (really) that bad?

When coffee beans are rotten, roasting them will smell awful. Good quality beans should not smell rancid when roasting, although some may find the smell of roasting coffee beans unappealing. Typically coffee lovers love the smell of quality beans roasting.

Although coffee is primarily an experience to the tongue, the nose and your sense of smell carry practically half of that experience. In this particular article, we will explore the exciting topic of the land of aromas in coffee.

Why Does Roasting Coffee Smell Bad? The Rancid Science Behind The Stench

Well, it doesn’t have to smell bad. Good coffee smells excellent, and rancid coffee smells rancid. However, roasting coffee can still smell pretty repulsive, and that’s because of a roasting method employed when buying cheap coffee beans.

If you are not aware of the differences between the three significant roasts yet (light, medium, dark), light roasts are often done when the roaster wants to preserve the coffee bean’s intricacy and origin flavors. 

When the beans are of bad quality, the tendency is that most roasters will overcook or burn the beans to hide their poor flavor profile and instead make them plain bitter, oily, and have them retain their smoky aroma.

So what happens during the roasting process, and why does burning coffee beans result in that extremely rancid smell? Well, it all boils down to chemistry.

When the heat is too high during the roasting process, what happens is that the cellular structure around the coffee bean breaks at a faster and more destructive rate.

This process would also imply that the oils are degraded and oozed out while the stored fats turn into fatty acids. Moreover, instead of producing a sweet aroma of caramel, the sugars carbonize, like burnt charcoal.

Have you tried caramelizing sugar? At first, it produces a waft of sweet aroma. When the heating process is prolonged, instead of the fragrant smells, a bitter, choke-inducing cloud appears, along with a pretty burnt smell. 

So remember, when the coffee smells rancid or rotten, it probably is!  Roasting coffee shouldn’t smell bad. And it might even be harmful, so read on to find out how.

The Dangers Of Inhaling Roasting Coffee

Although many have observed the repulsive smell that most bad coffee beans make when they are being roasted, not many people are informed that there are real dangers to inhaling the scent of roasted coffee beans for an extended amount of time.

And no, I am not talking about a one-time occurrence either, and the truth is that there is a potential danger when it comes to constant inhalation of the aroma of brewed and or brewing coffee beans.

Harmful Chemicals Found In Fumes Of Roasted Coffee

• diacetyl (also known as butanedione)
• acetyl propionyl (also called 2,3-pentanedione)

When appropriately roasted and are sourced accordingly, coffee should have a pleasing aroma that boosts you up every morning. However, in a report by the Milwaukee Journal Sentinel, there seems to be a presence of harmful compounds in roasted coffee, such as diacetyl (also known as butanedione) and acetyl propionyl (also called 2,3-pentanedione).

Although most diacetyl and acetyl propionyl problems arise from their artificial butter flavoring form, these chemicals can occur naturally during the roasting process.

The Food and Drug Administration or the FDA has approved both of these products as safe for ingestion. So chill out and do not go and throw your coffee packets just yet. However, when these products are inhaled for long periods, they can cause detrimental damage to your lungs.

The Coffee Drinker Is Safe

Although it would be pretty tempting to abandon ship and leave the coffee train already, especially since your health is on the line, you probably are not at risk. In addition to that, if you are a regular coffee drinker that buys coffee in cafes or makes only one to two cups of coffee every morning, then no, you are a hundred percent not at risk.

Most reports by the CDC are concerned with the health and safety of the workers who roast, grind, or package coffee on an eight-hour basis for five days a week.

Moreover, there have also been reports that although baristas have a higher risk, they won’t be too affected if their working space has proper ventilation. So don’t leave just yet! Coffee is still your best friend, and you shouldn’t be too scared of giving yourself your daily fill of caffeine.

Lung Attack: The Consequences Of Constant Exposure

There have been real-life recorded consequences of over-exposure to these flavorings. In a news report by Sentinel Source, workers in a popcorn factory have shown deterioration in their lung health and untimely deaths.

The flavorings in question are the butter flavorings naturally found on roasted coffee beans: diacetyl and acetyl propionyl.

The horrible thing about this is that these deteriorations in lung health are irreversible. In another report, five workers in a coffee processing plant in Texas were diagnosed with bronchiolitis obliterans, a severe lung disease, and is potentially fatal.

How Will I Know If The Coffee I Am Drinking Is Nasty And Or Rancid?

The physical appearance of rancid and non-rancid coffee is hardly distinguishable, so better give up on that. However, your nose can be a huge help in these situations.

Grab a small bunch of these beans and smell them. If there is that aromatic fragrance, then probably, your coffee is good to consume. However, if it has a not-so-good aroma, leave it and get yourself a fresh batch!

For brewed coffee, the consensus is for you to taste a tiny bit of the cup. Leave it for an hour, and when it tastes extremely bitter, yet sour at the same time, what you’ve got there is probably rancid coffee.

How Will I Know If The Coffee I Am Drinking Is Old?

Ground coffee can only last for three to five months, so anything more than that is probably rotten. Moreover, if your coffee is a few months old, it is perhaps not as delicious as fresh coffee and may taste old.

However, if the package has been opened, be sure to make use of it as quickly as possible, as it will deteriorate faster (in a span of a few weeks).

How Long Will My Cup Of Coffee Last?

Many factors can affect how long coffee can last. Of course, there is always the question of whether the beans used for brewing are fresh. Coffee in of itself lasts for three to four days in the refrigerator, but leave it for an hour outside, and your cup will already turn stale. 

However, when considering how long a cup of coffee lasts, you should also consider the ingredients mixed with your cup. For example, lattes last significantly shorter when compared to Americanos. Because lattes have a significant amount of milk in them, they get bad pretty quick.

Because milk is pasteurized, it can last for a long time. However, when opened, milk boxes last for only three to four days, and they even deteriorate faster when exposed to open air. It would be best not to drink that latte anymore when there is a sour aroma or taste developing (especially curds).

Key Takeaways: Summary

Roasting coffee shouldn’t smell, and if it does, there certainly is something wrong with your coffee beans. If the resulting cup of coffee is sour yet bitter simultaneously, the coffee beans and or the cup of coffee might already be rotten.

Although roasting coffee should smell aromatic, that does not mean that you should inhale it for long periods. If you are a roaster or a barista, make sure you wear face masks and have proper ventilation. Roasting coffee produces compounds and chemicals that have detrimental effects.

Frequently Asked Questions

Does Roasted Coffee Smell Like Toast?

Although fragrant chemicals exist in green coffee, they are not discernible until the beans begin to secrete moisture and caramelize. A grassy fragrance will emerge halfway through the procedure as the beans start to yellow, and as the beans tan, they will smell like toasted bread.

What Does It Mean When Coffee Smells “Grassy”?

The “grassy” smell in coffee is a smell often attributed to coffee that’s just started roasting and is still to achieve the first crack. 

What Does A Good, Freshly Roasted Coffee Smell Like?

Good, freshly beans will give off a sweet, fragrant aroma, especially as they run through the first crack. However, coffee beans roasted for longer will have a brown sugar smell, and keep it there, and it will smell like burnt rice.