BY JULIAN DAMMENHAYN

Are you a production roaster pumping out 100’s of kilos of coffee per week, or a home enthusiast roaster trying to nail a roast for your morning brew? If so, how do you test the quality of your roasts? There are many options such as the widely adopted method of cupping, or of course your classic brewing methods, espresso and filter. Today we pose the question, what is the most effective method for coffee quality control?

Coffee quality control (QC) is a very important part of our weekly routine here at the roastery. We have to make sure that our beans meet the standards of consistency and quality for our customers. To do this we have a number of checks we do to ensure that we are always achieving our goals. Today we will be delving into cupping and espresso as methods of QC, and questioning how effective each of these methods is at varied roast degrees, namely filter, and espresso.
On a weekly basis, we roast anywhere from 30-50 different roasts across 3 different roasting systems, from biggest to smallest, Joper, Diedrich, and Ikawa roasters. Once we have finished roasting for the week, we take a sample of each roast for QC and various tests including weight out, moisture, roast density, and Agron colour readings. All of these tests indicate that everything has gone to plan and we are on the right track to meeting our production goals.

The next logical step is to taste, this can be done in a number of different ways: but which method is best for what? The Industry standard for flavour assessment or quality control (QC) is to ‘cup’ the samples. This involves placing 8.25 grams of coffee per 150ml (optimum ratio) into a bowl and pouring hot (95 degrees) water over it. After breaking the crust and cleaning the grounds from the surface of the cup, you then take a spoonful and slurp away. Cupping has been adopted as very common practice for QC across the coffee industry. This is more consistent than making an espresso, for example, as there as fewer variables involved. Just pour water on it!

Cupping, however, originates from the process of buying and selling green coffee. Importers would cup and assess coffees at origin and give them a score based on their aroma, sweetness, acidity, body, flavour, and aftertaste, this would determine what that coffee is worth (to extremely oversimplify the buying process). This happens many times reassessing the same samples again and again, for this reason, cupping is the most effective way to assess a large number of samples.

Coffee samples are often roasted very light in an open-fronted drum roaster, or more recently in sample roasters like the Ikawa air roaster. This process works very well for this roast degree, but what happens as the roast degree gets darker? As we progress from a light sample roast to a more developed filter roast, then into first and second crack espresso territory, is cupping still the most accurate QC method? 

There are a number of situations that require different QC approaches.

Are you checking for roasting or green defects?

Are you trying to develop a roast profile to better unlock a flavour profile of a coffee?

Each of these areas of QC have different approaches that should be taken into consideration to get the best evaluation of the coffee, depending on the roast degree.

So let’s start with filter: Being the lightest roast degree, cupping is an accurate QC method for both of the QC situations above.

You can see flavour shifts from the cup to the brew, but mostly they will be shades of one another unless your brew method and cupping protocols are extremely different. Say for example if you are brewing with an extremely coarse grind, you may have a much thinner bodied acidity-driven cup, with some lighter flavour notes than the cupping bowl. We cup all of our filter roasts and brew each roast throughout the week, not only because they are tasty, but we also get a good idea of what is going out to our customers and how they can optimize it.

Let’s move on to espresso: this is where your intent of your QC must be clear. For example, every week we cup all of our production roasts, a quick pass of one cup of each sample. This is just to double-check that nothing has gone horribly wrong, whether it be roasting or green defects. This quick pass in conjunction with the roasted coffee measurements leaves us with no doubt that we have done our job correctly. If for any reason the measurements of a coffee are out of the normal range, or a coffee sticks out as not tasting like it normally should in the cup, this is when we would dial it in on the espresso machine. Making espresso is the final step in assessing for faults, and will tell us if we have to make any adjustments, big or small. 

When looking at flavour modulation of espresso, we always put the coffee through the espresso machine. Even though it can be time-consuming dialing in each coffee, cupping does not give a close enough approximation of how a coffee will taste once ground fine and slammed under 9 bars of pressure, whether it’s at the roastery or in a café setting. If you rely on cupping too heavily when looking to develop roast profiles, you can end up with coffee that tastes great on the cupping table, but not so great as an espresso.  It may also either be insoluble through the espresso machine, or the flavours you are tasting in the cupping bowl may not be there in your espresso. As a very general rule, we have found that the darker the roast, the more cupping starts to give an inaccurate assessment of what the final product’s flavour characteristics will be as espresso. If you are aware of YOUR roasting style and learn how YOUR espresso roast tastes on the cupping table, you are able to make educated assumptions of how they will translate across, even more so if you have taken a lot of roast measurements to reference, but these factors can vary from origin to origin, and process to process. 

In summary, we think cupping is a great means for highlighting roasting or green defects or assessing your filter roast flavour profiles. However, for espresso, we would recommend evaluating most of your flavour developments through the espresso machine. As the roast degree gets darker, the cupping bowl notes may not always translate over to the machine, potentially giving you a false direction when developing a roast profile. It is also extremely helpful to take as many measurements as possible, as these can be very telling of faults. This is only our observation on our roasting style and may be different for different roasters approaches and machinery, but we hope you too can find it useful along your coffee journey.

Note: If you have any insights into QC or any other questions, don’t hesitate to share either in the comments below or on one of our social platforms!