November 19, 2019

How to Ensure Consistency When Cupping Coffee


What good are your cupping notes if the coffees on the table haven’t been extracted to the same degree?

Cupping is an indispensable tool for anyone wanting to buy, sell, or roast coffee. It’s used to compare lots, identify profiles, spot green and roast defects, make purchasing decisions, and determine farming and roasting methods. 

This makes accuracy and consistency in cupping sessions crucial. To find out how best to achieve this, I spoke to Danny Pang from Technical Sales at Marco Beverage Systems, who has been an international judge in Cup of Excellence competitions, and the team at Common Man Coffee Roasters in Singapore.

Lee este artículo en español Cómo Garantizar la Consistencia Durante Una Cata de Café

Coffee cupping at the 2018 Honduras Cup of Excellence. Credit: Marco Beverage Systems 

Why Is Consistency in Cupping Important?

“When you make any business decisions, having accurate, consistent information is always key,” says Matthew McLauchlan, Executive Director at Common Man Coffee Roasters.

The mineral composition of the water and its temperature, the number of fines and boulders in the ground coffee, variations in roast method, and even the local temperature can affect a cupping session’s accuracy. This will leave you working with unreliable data.

“What we want to do is be able to analyze or evaluate the coffee itself, and to do that, we have to first standardize as many or all of the other variables within that brewing process that we can, to ensure that when we’re tasting or comparing samples, the only difference in those samples is the coffee itself,” Matthew continues. 

You might also like How to Limit Water Temperature Variation For Better Coffee 

A cupping assistant pours hot water into vessels. Credit: Marco Beverage Systems 

Variable 1: Water Quality 

The mineral composition and hardness of the water not only affect how the water tastes but also the extraction of the ground coffee. As such, cupping coffee in different locations can result in different scores and profiles, unless the water quality is controlled.

“In terms of the water standards, obviously that is a hugely important variable because water makes up such a massive proportion of the brewed coffee that you’re tasting,” Matthew says. 

SCA cupping guidelines state that water should be “clean and odor-free, but not distilled or softened.” Ideally, it should have a TDS of 125–175 ppm. 

You should know the quality of your water. Danny says, “To ensure that the water is used consistently across all cuppings, water from one source is tested with the water test kits and when it meets the requirements, it is used as the only source for cupping throughout the cupping sessions.” 

Matthew also tells me that sometimes roasters even bring their own testing packs to cuppings, which can include refractometers to measure TDS. 

Don’t forget that a source’s water quality can change. Danny recommends checking it weekly if you’re using it for cupping.

Honduran cupper Juan Carlos Guerra watches as water is poured onto coffee samples. Credit: Marco Beverage Systems 

Variable 2: Water Temperature 

According to the SCA, water should be approximately 200ºF/93ºC at the moment it is poured onto the coffee grounds. Controlling this, however, can be tricky.

It is important to use equipment that offers temperature precision and stability. Matthew tells me they use a Marco PB10 water boiler “built around stability for temperature.”

Another issue can be the loss of temperature due to contact with air. Matthew recommends dosing the water into the cups as quickly as possible and minimizing the time between each cup.

Danny says that during Cup of Excellence sessions, this issue is addressed by using large water kettles. “Hot water off the boil is poured from a kettle that holds up to four liters and poured into as many as 20–22 cups from one end of the table to the other, filled to the brim, all in one and a half minutes approximately.” 

The kettle shape is important, and Danny advises against using gooseneck ones. “The comparison between coffees would definitely be unfair, with the first cup receiving the hottest water, and the last cup receiving the coolest water, because goosenecked kettles cause a tremendous loss of heat during pouring as they increase the surface area of water in the gooseneck.”

Precision matters. A few seconds lost here, or a half-degree difference in temperature, might not sound like much but it can affect the extraction of the coffee. Matthew says, “It’s key to ensure that the samples on the table remain consistent and that the analysis of each sample is really just about the coffee and not necessarily about a difference in brewing temperature.” 

An EcoBoiler from Marco Beverage Systems on display at a roasting competition in Indonesia. Credit: Marco Beverage Systems

Variable 3: The Roast

If you are comparing the potential of green coffees, as opposed to evaluating potential roast profiles, it’s important to minimize discrepancies caused by the roasting or degassing. Your roaster should be aware of SCA protocols for sample preparation, including the measurements of the roast level, the rest time, sample storage conditions, and more.

Comparing the roast levels of ground coffee samples ahead of cupping them. Credit: Marco Beverage Systems 

Variable 4: Grind Size 

“Grind size is probably the trickiest one to try and follow an international standard on, just because it tends to be one that’s a little harder to try and quantify,” Matthew tells me. 

While a water dispenser can give you water heated to the exact degree, and you can measure roast profiles on a variety of scales, grind size is a little more difficult. However, it is crucial to get the correct grind size and limit fines and boulders as much as possible. Pay attention to grinder quality and use tools such as sieves to ensure consistency.

SCA protocols state that coffee samples should be weighed as whole beans and ground no more than 15 minutes before infusion. The grind size should be slightly coarser than what is typically used for drip brew, with 70–75% of particles able to pass through a US Standard size 20 mesh sieve. The SCA recommends that at least five cups from each sample are prepared in order to evaluate sample uniformity. 

Be aware of the potential for contamination in the grinder, too, due to grounds left behind from previous coffees. The SCA recommends that before grinding the cupping sample, a small quantity of the same coffee should be ground and discarded. This will mean that any stray grinds should at least be from the same coffee.

A Honduran cupper evaluates coffee aroma. Credit: Marco Beverage Systems 

Variable 5: Processes 

Repeatability goes hand in hand with consistency, and having strict processes will help you achieve it. As Matthew tells me, “Say, you get halfway through the cupping table and then you let it cool down for three minutes because you have to go take a phone call and you keep pouring. Obviously, a lot of the cups will already start brewing, so you have some over-extracted and under-extracted samples.” 

Yet even much smaller variations can impact the repeatability of your results. Danny tells me that cuppers should: 

  • Break the crust in three stirs, without being so vigorous that the agitation could impact extraction. 
  • Remove the broken crust without digging the spoon into the cup and so causing significant agitation. 
  • Rinse the spoons in clean water and dry their edges after each slurp to minimize cross-contamination between samples.
  • Stay silent during the sessions to avoid influencing someone else’s opinion or simply distracting them. 

A cupper breaks the crust on samples. Credit: Marco Beverage Systems

Variable 6: Cuppers

A trained team is key to standardization. “Having experienced cuppers will enable the team to be well-calibrated, leading to more effective communication and consistent scoring,” Colin and Tam, part of the Roast Team at Common Man Coffee Roasters, tell me. 

However, this is also the variable that can be the hardest to control. Danny tells me that cultural experiences may mean that cuppers’ references points are different when it comes to food and taste. 

To counter this, cuppers for competitions such as the Cup of Excellence must meet certain requirements. “The cuppers not only must have the necessary prerequisite of cupping experiences in terms of years, but they also need to be currently and regularly cupping, and to add to this, attend a few rounds of calibrations for each event that they are cupping at,” he says. 

For producers and roasters, it can be worth training the team together and also having tasting sessions of the fruits, spices, and other foods commonly used as references. This is particularly relevant if you have teams in different countries. If your cuppers in Asia are used to dragon fruit and yuzu, it may benefit your European team to also be familiar with these fruits. You could also consider calibration exercises such as comparing how they cup samples of the same coffee.

Preparing a cupping of Honduran coffees. Credit: Marco Beverage Systems 

When cupping forms the basis for significant business decisions, from coffee purchases to roast profile development and identifying micro lots for experimental processing, it’s important to get it right. You need results you can trust. 

So, quantify as many processes as possible. Train your team. And pay close attention to the roast, grind size, and water quality and temperature. The effort will pay off.

Feature photo: A cupper evaluates coffees at the 2018 Honduras Cup of Excellence.

Please note: This article has been sponsored by Marco Beverage Systems.  

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