How do you choose green coffee beans?

When a coffee roaster gets a bag of coffee or is testing samples, they don't make a big pot of coffee and sit around drinking it and eating cookies. They follow a standard procedure that all roasters and graders follow to evaluate the green coffee and determine it it's suitable for production. Cupping is more than spitting coffee into a spittoon. It's a intricate procedure that takes years to master.  

The most important piece of cupping equipment is a sample roaster. It's a miniaturized version of a roaster that is fully functional. It holds 8-16oz of green coffee and works basically the same as a large roaster. It’s usually electric and fits on a table top. You measure out a predetermined amount of coffee and put it in the roaster. For cupping ALL samples are roasted to just after first crack. This is the standard. When you cup, there is a full procedure from roast to tasting that must be followed every time.

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If you want to me more precise, you use an Agtron machine and roast the green coffee to a score of 68. An Agtron can identify the color of the coffee.

Once the coffee is roasted it should be used within 24 hours and cooled for at least 8 hours.

After the samples have cooled, they should be kept in air tight containers until cupping. Once you’re ready to cup, you grind the coffee no more than 15 minutes before you’re ready to cup. Measure out 8.25 grams of coffee ground so that the bulk of the ground coffee pass through a standard US size 20 sieve. The amount of coffee used should be measured when the beans are whole. A “cleansing” quantity of beans should be run through the grinder before the real samples. Measure out enough coffee to make 5 cups of the same bean.

At this point you take your first data point. Smell the ground coffee and assign a score from 1-10. Since you’re using quality green coffee, most scales start at around a 6. You should have a standardized form where you can record this data.

The water used should be odor free and not distilled or softened. The water should be heated to 200F and 150mL should be poured directly on to the coffee. The cups should be filled to rim.

After 3-5 minutes have passed, you’re can now take you cupping spoon (kind of looks like a soup spoon but it can hold more liquid) and break the “crust”. The crust is the grounds that float to top of the cup and it traps all the aroma in the cup. You push the grounds to the bottom of the cup and stick your nose as close to the coffee as possible. You take in the aroma and assign this aroma a score (repeat this three times to get you score).

In a cupping session you could be sampling one coffee (five cups total) or multiple coffees (number of coffees X five cups). It is important that you have a cup of warm water on the table so you can cleanse you spoon between samples. You want to have one or two for each tester so everybody has their own.

After you have tested all the samples, wait at least 10-15 minutes before moving on to the next step. If you have many samples, this time has probably passed by the time you’ve made your way around the cupping table. At this point you can now carefully remove the coffee grounds from the top of all the cups. These can be discarded. The cups of coffee must be at 160F before moving on the the next step.

The reason you wait for the samples to get to 160F is that you now have to taste the samples and you don’t want to burn your tongue. If that happens, you can’t properly taste the coffee. This is where the fun begins. You can smell the coffee again. Take some coffee in you spoon and slurp the coffee into your mouth as hard as you can. You want to coat as much of you mouth as you can. The further back the coffee can get, the more you can use your olfactory senses to help taste the coffee. Some people spit the coffee into a spittoon after they taste it. This is up to the taster and how much coffee they sample.

When the samples reach 100F you repeat the process and record your score. Sampling should stop before the samples reach room temp.

When you score the coffee you also have to follow a standard protocol. The categories used are:

  1. Fragrance/aroma- the beans are evaluated first within 15 minutes after grinding and second, 3-5 minutes after steeping by breaking the crust and smelling the coffee. They score for fragrance is a combination of wet and dry aroma.

  2. Flavor- Flavor and aftertaste are evaluated when the coffee has cooled to 160f. Acidity, body and balance are evaluated between 160f- 140f.

  3. Sweetness, Clean cup, Uniformity- these are evaluated when the coffee is reaching room temp (below 100f).

  4. Overall- this is a value given to the overall taste of the cup.

  5. Defects- negative scores are given for unfavourable flavors.

You then tally up all the scores and compare it to for following table:
 

Total Score Quality Classification

90-100

Outstanding

Specialty

85-89.99

Excellent

80-84.99

Very Good

<80.0

Below Special Quality

Not Specialty

To be perfectly clear, this process is not to qualify the roast of the coffee. This process is to qualify the green coffee before you roast it for sale. In the beginning your palate will not be refined. Your analysis will be very binary in the beginning (good vs bad). You have to refine your palate by tasting a lot of different flavors and smelling different smells. These seem like easy tasks but you have to taste and smell like it’s your first time experiencing everything.

Most people won’t ever do this. They don’t have to. They can but coffee from someone who has already taken the time to find and roast the best beans they can find. All you have to do is brew a cup and enjoy.