Roasting Coffee Beans Twice? (Here’s What You Need To Know)

My relative once owned a small café on a quaint side of town, and what they would often do is buy pre-roasted coffee beans and roast them again once before serving them.

I thought it was pretty standard, but in hindsight, I realized that such a process was just so different (not wrong per se, but different). It seems that you are here for the same question as well, asking if it is possible to roast coffee beans twice.

Anyone can roast coffee beans twice, but not everyone does it, and in fact, it rarely happens because double roasted coffee, or coffee using beans roasted twice, will negatively compromise flavor.

Of course, all of this is subjective, and no one can honestly say which is better; after all, the said relative of mine still has regular customers to this day. However, in this article, I will help you determine what double roast coffee is and if it is a good fit for your taste.

What Is Double Roasted Coffee?

Double roasted coffee is such a rare occurrence that rarely anybody talks about it. As such, it may be hard for you to find some resources that can truly define what double roasted is. 

However, the truth is that double roasted coffee is defined precisely like how it is named. Essentially, it is coffee roasted twice, and it can take on many forms as well. There are specific variants, such as triple roasted coffee, which is coffee roasted thrice (obviously).

Double roasted coffee can be a combination of two roasts: a medium roast and a dark roast or a medium-dark roast and a light roast. However, the most common type of double roast happens when someone roasts beans too lightly, causing them to re-roast said beans to utilize their bitter taste notes.

Why Not Roast Coffee Twice Or More?

The roasting process is an essential step into defining the coffee’s taste. This process can make or break a cup, and you might be disappointed that even the finest of coffee beans will go to waste if not roasted properly.

Think of it as eating Kobe beef (the most expensive beef on Earth), but the chef has made it so that it is undercooked; it would not taste good, would it?

One of the essential things that can happen during roasting is the Milliard reaction, which comes around the first crack of the roasting process (named the first crack since, during this process, the beans break open, producing an audible “crack”). 

This reaction is one of the primary reasons why double roasting is a frowned-upon practice among baristas.

Reasons Why Roasting Coffee Beans Twice Is NOT A Good Idea

• The Millard Reaction problem
• Aroma compromise
• Acidity is down
• Flavor is muted

The Millard Reaction

If you have ever grilled meats before, fried onions, or have baked bread; then there’s a good chance that you have witnessed a Millard reaction in action. The Millard reaction is a non-enzymatic reaction due to amino acids and sugars, causing bread, meats, onions, and coffee beans to brown.

What is impressive is that this reaction causes these foods to develop their flavors, like when onions develop their umami flavor or when your coffee beans develop their distinct aroma, the floral notes, the sweetness, and acidic compounds.

What makes roasting so crucial in the first place is that the Millard reaction creates a beautiful burst of aroma and flavor during the first roasting, a key component where you can experience your coffee at its finest.

However, during the second roasting, or when you roast your coffee beans twice, what happens is that most of the time, the Millard reaction does not occur again.

So instead of theoretically redeveloping the coffee bean’s flavors by re-roasting, what happens instead is a pain-staking process of your coffee turning into burnt charcoal.

Flavor, Time, and Bitterness: A Love Triangle

Now that we have talked about the Millard reaction let us talk about one of (if not) the most essential qualities when it comes to determining whether roasting coffee beans twice is a good idea for you (or not), and that is the flavor of the coffee. After all, what’s so good in a horrible tasting coffee?

According to a study conducted by Münchow, Morten, Steen, and Giacalone, there is a positive correlation between the time it takes to roast coffee (i.e., double roasts) and the bitterness levels of the said coffee.

What positive correlation means in this context is that whenever you increase the amount of roasting, you also increase the prominence of bitterness.

With that in mind, it means that when you find your coffee not bitter enough for consumption, double roasting is a pretty good option. In addition to that, if you have under roasted coffee and are thinking that it would be beneficial for your coffee to be more bitter, double roasting is a viable option for you!

However, be careful when double roasting medium roast and dark roast coffee, and when you find medium and dark roasts “too bitter,” stay away from double roasts as much as possible.

Another thing to notice within the said study is that the proponents also noted how an increase in roasting time was indirectly proportional to sweetness, fruitiness, and overall complexity. If you genuinely like complex flavors within your coffee, then double roasting is not for you.

Expect Acidity To Go Down

Most non-aficionados of coffee like to believe that what defines coffee as “coffee” is the bitter flavor and maybe some hints of sweetness.

Still, in reality, what makes “coffee” the coffee you know is acidity, and how without it, your cup of coffee would be like bitter gourd juice roasted to near burning levels. 

Acidity is the lifeblood of coffee, and the best cups of coffee in the world are acidic, as with acidity comes all the mellow, exquisite flavors you come to expect. 

According to a study, researchers have found out how the correlation of citric flavors (acidity) and aroma (the smell) are direct and indirect with the roasting time and temperature.

To understand it better, let me put it this way: the acidity of coffee, along with its flavors, and aroma decrease drastically along with longer roasting times, especially on double roasted coffee.

However, keep coffee roasted to a lesser extent (in time and temperature), and you will notice a significant increase in the aroma and citric flavors.

Frequently Asked Questions

What Happens To Oil When You Double Roast Coffee?

 Oil increases as you roast the coffee longer. In theory, this would mean that double roasted coffee is very oily. In certain situations, that would be true, but most of the time, the oil will not exist and what would retain is a very stale flavor of a month-old coffee.

What Is The Difference Between Sour And Acidic Coffee?

Sourness is the reason why acidity gets such a bad reputation. Acidic coffee does not mean that the coffee you will be drinking will be like stomach-wrenching vinegar. However, the reality is that acidity does not equate to sourness.

In actuality, acidity is more than sourness, and it comes with a long list of flavors that blend so well with it. An example of these said flavors is sweetness and the citrus, nutty flavor of the coffee.

What Is The Correlation Of Roasting Time And Other Variables That Qualify A Cup Of Coffee As Good?

Concerning stringency, body, bitter flavor, burned aroma, and residual, typical, and burned tastes, there has been a direct correlation to roasting time. This data implies that burnt tastes, bitter flavors, and stringency increase when roasting time and roasting temperatures increase.