Improve Your Coffee Roasting Using Green Size Screens (Sieves)

Should coffee roasters worry about BEAN size?

What is the difference between grades and sizes?

As a specialty coffee trainer and quality control consultant, I wish I could say that proverbial lead in that, “I always have clients ask me…” Sadly I can’t say that anyone is asking. Perhaps many roasters understand the importance of coffee sizing when it comes to roast impacts:

• The size of coffee beans directly correlates with the surface area available to absorb heat during the endothermic roasting stage (before first crack). Thus larger beans roast at a different rate than smaller beans - maybe faster, maybe slower.

• The size of green coffee is indirectly related to coffee density - a common idea that most all roasters prescribe to the adage that “higher density coffee = better coffee”. No entirely true, in defense of low elevation coffee growers.

• The size of coffee beans affects the way a roaster should blend for even distribution in the bag and in the espresso hopper where consistency between brews and shots is critical to clients.

Find dramatic improvements in roast quality using green sizing screens (sieves)

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Before we get too deep into sizes and quality, let’s take a moment to consider where various coffee bean sizes come from. Coffee cherries from the same tree and branch grow along the stem of that branch. The coffee plant transfers nutrients up from the roots, through the trunk and out the branches. Those cherries closest to the trunk will naturally get water and nutrients before those at the end of the branch. If the soil is rich in nutrients and everything the plant needs to be happy, then the produce is abundant with less variance. If the plant is strained those cherries closer to the trunk may get nutrition first, while those further down the branch are lacking. I am not an agronomist or growing expert, but I am a farmboy and you can see how the logic holds that some coffee will be larger, some smaller, and all may potentially differ slightly in the organic composition in fruit and seed.

Aha! Where are most peaberries found?

At the end of the branch where the fruit can only support one seed rather than two!

As I said in my video, there may have been a time where it was reasonable to believe “bigger beans are better beans” and give monikers like “AA” or “AAA” or “Supremo” which insinuate a quality measure. However, today we enjoy a modern era where technology can be held in the hands of farmers and growers. Science, data and communication tools can relay growing and harvest conditions between farm, mill and warehouse for roasters to benefit. It is now time for roasters to recognize (and benefit from) the great advances at origin.

Furthermore, roasters may be willing to pay just as much, or more, for Kenya AB or for a Central Segunda lot, if roasted effectively. We can reward growers and producers for ALL of their coffee when we recognize and appreciate what each size can do!

GOAL #1 = Promote more strict coffee sizes protocols for roasters.

I believe that roasters should do their part to own screens and build them into a quality control program. Most “specialty coffee roasters” are going to great lengths to monitor quality and roast for nuances with a goal to Wow! their customers. However, they may find that one VERY EASY giant step forward is to roast the 17-18’s separate from the 15-16’s. That subtle size difference causes a variance in roast development … i.e. the nuances of fragrance, aroma, sweetness, acidity, body, mouthfeel, cleanness, and cupping score!

GOAL #2 = Promote dramatic gains for coffee Producers.

How can coffee producers recognize dramatic gains from strict coffee sizing? When roasters take the first step to understand that an 18 screen size (18/64th inch or 7mm) roasts, cups and blends very different from a 15 screen size (15/64th inch or 6mm) then they will begin to value coffee of all sizes for it’s specific use.

I encourage growers to sort coffee strictly, label clearly, offer documentation and sell it at a premium using universal language SUCH AS:

This is a 98% strict screen size 15-16 (6.0-6.5mm) triple sorted clean coffee.

This is a 98% strict screen size 19-20 (7.5-8.0mm) clean shaken natural coffee.

When roasters value 15’s then they will pay growers more appropriately for those once considered inferior beans. Roasters love to tell customers about farms and regions and Meters Above Sea Level (m.a.s.l.) but the truth of the matter is that many times these coffees are coming from farm regions, at various elevations, from various farms. When growers bring them to the central processing station they get blended together.

Perhaps roasters could be proud to share, “We support underdogs and to prove it roast the most delicious small bean coffee. We like to buy the small beans to help the growers, and personally we enjoy their nutty floral qualities!”

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More could be said, I’ll step off of my soapbox. What questions or disagreements might you have? I’d love to learn from your perspective and keep the conversation going towards great understanding, improved quality control and more fair recognition for ALL coffees produced by growers.

Thanks for reading! (and watching)

Find roasting and cupping gains by using green coffee screens (sieves).

Coffee Community - Thailand Special Anaerobic Natural Process

A big shoutout to Tanasak and his team at CY Coffee for this most amazing coffees I have EVER had from Thailand!

Thank you!

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Washed Coffee,
Special Washed,
Super Honey, and
Anaerobic Natural Processed!

If you’re ever in Bangkok, Thailand be sure to look up CY for a fantastic coffee experience. Located at: 12 Sukhumvit Soi 10, Bangkok. Thailand

 

Wow!

I offer a deeper look into each of these coffees, their measures, moistures, densities, roasts, ROESTs and cupping with QC feedback. More good stuff to come! CY Coffee from Thailand was one of three that were QC’d in tandem. Tune in to all 3 and see separate posts for specific photos and details in this blog.

Thanks for watching and growing with me!

IF THIS WAS A WORTHY READ, PLEASE CONSIDER SHARING AND LIKING.

THANK YOU!

ADAM

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PART - 1

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PART - 2

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PART - 3

Welcome to the Community!

Join Email for Discounts: http://eepurl.com/cZU5R1

Enjoy the Playground!

Find SCA Training: www.howtocoffeepro.com.

END 😃

How to Grade Green Coffee - Size, Defects, Scoring Quality.

How is green coffee graded?

What is a coffee quality score?

And, what grading criteria do we USE?

We’ll answer these 3 questions and more in the following discussion. For some coffee fans, this may feel like information overload. For other coffee pros, this may be a good primer to whet your appetite for the SCA Green Coffee Foundations course. More to come.

Coffee is “green” before it is roasted.

Coffee must be roasted before we can brew and enjoy it.

If you are a coffee roaster, then you have probably been solicited by green coffee sellers. They promise a beautiful crop and offer to send or drop off samples free of charge. They ensure you that this green coffee is off high quality at a great price.

However, it is very common that you may receive a 100g-300g sample which was cleaned by hand, to help you (the green buyer) to have a great first impression. This would in turn lead you to consider buying on the basis of a non-representative sample. After all you’ll be getting the real deal, from a 60kg bag.

As a roaster you may be convinced - this coffee is great! It’s clean and tastes great. “Give me 10 bags!” However, months later when the 10 bags roll in strapped to a +600kg pallet you may find that the coffee looks less clean. We’ll talk about “clean” and “defects” soon.

This may be a dramatic (I hope as a roaster you have had many positive experiences), but it does happen quite often that samples do not represent the actual product. So let’s consider what variables contribute to creating our Green Coffee Grading Scale. As a buyer, it’s essential we are on the same page as our seller.

When Grading Coffee on a Scale:

1. We grade by size

2. We grade by defect count

3. We grade by cupping scores

4. We grade by other criteria (elevation, etc.)

   Together - we harmonize for common language

Size Matters, Or Does It?

Let’s talk about coffee size ratings and how they can easily lead our judgement astray. There are 2 major principles at work here when discussing size of coffee beans. One is much more important for final quality than the other. However, valuing (pricing) the coffee may not correlate in the end.

First, coffee beans should be sorted, shaken, sifted according to size. As a specialty coffee buyer, we seek a homogenous size when purchasing. A beans size should be as close as possible to it’s neighbor. Small beans are all together, medium beans are separated, and so on.

We measure size with coffee screens. Each size on a coffee screen is an incremental measure - the size of a hole in the screen. Those increments increase stepwise by 1/64 an inch. The most common screen sizes (diameters of holes) range from 10-20. Stated another way, super small beans fall through 10/64 inch (4mm) diameter holes while super large beans are suspended (not falling through) holes with a 20/64 inch (8mm) diameter. We would grade those small beans “screen size 10” while we grade the large beans “screen size 20+”. The graphic below offers some clarity and breakdown with conversions for various countries.

As you can see above (we are not to the 2nd point yet) there is some language introduced which could be misleading. Calling super large beans “AA” or “Supremo” sounds much better than a “B” or “Terceras”. Many taste tests have been done and we cannot conclude that large beans taste better (or worse) than small beans. More on that soon.

The second point, is about homogeneity. A coffee roaster wants their coffee to taste as good as it can, no matter where it comes from or how large the bean is. An essential part of roasting great coffee is consistency of roast development. Imagine roasting large items (beans) with very small items (beans). The large will roast at a different speed than the small and require different amounts of heat. When one is properly roasted another will not yet be ready. When the other is finally roasted properly, then former will be overdeveloped or burnt. This is an unfortunate and common phenomenon when large and small beans are all mixed together. There is also much more to be said about blending for espresso, but that will be left to another discussion entirely.

Defects Matter!

The best coffee is clean coffee. So how do we understand what is clean or “dirty”? Defects come from several key areas. One is pre-processing - something resulting from the farm and from nature. Another is during processing - something from mishandling or missteps in the process of removing seed from fruit. Another is during storage - before the coffee ever gets to a roastery (or heaven forbid in your roastery) while it’s sitting in the bag, on a truck or in storage.

Defects are also broken down into 2 categories: Primary and Secondary Defects. Primary defects will knock your coffee out of “specialty” status with just 1 or a couple present. If your coffee has a few Secondary defects it may still qualify as “specialty” but you can’t have too many or it will again fall out of “specialty” status. It’s a simple chart to follow, but the challenge is personally delineating what defects constitute and to what severity each is. This is where working with a professional or getting some basic training in Green Coffee comes in helpful.

Insert plug with link for Green Coffee Foundations course : )

Cupping Scores (should) Matter!

It could surprise you that traditional coffee grade metrics are not based upon cupping scores. I can see a valid argument for and against this. We’ll look at both perspectives.

“Cupping” is a coffee term where we run quality control on a batch of coffee. It’s also super cool and super nerdy for many specialty coffee pros. Imagine a bunch of professionals dipping spoons into community bowls slurping and spitting with expressions of Mmmm… Ohhhh… while making notations on clipboards.

The notes we take in cupping constitute a score where 100 points are possible. No one ever scores a coffee a perfect 100. The most rare and beautiful coffees score in the 90s. Good coffees (and the majority of specialty) fall within the range of 82-88. However, when a coffee scores below 80 points, we must remove “specialty” classfication for it. Below 80 coffees are considered “commercial grade”.

Coffee Cupping Scores are comprised of:

• Fragrance (quality and intensity)

• Aroma (quality and intensity)

• Acidity (quality and intensity)

• Body (quality and intensity)

• Flavor (quality)

• Aftertaste (quality)

• Balance (quality)

• Sweetness (yes/no presence)

• Uniformity (yes/no)

• Clean cup (yes/no)

• and an Overall rating (quality)

What does it mean, to not be clean?

If a coffee is not uniformly clean, then there is a “Taint” (minor infraction) or a “Fault” (major infraction). If a coffee has a Taint it is penalized -2 points for every cup with the taint. Many small human errors within the supply chain can introduce taints. The coffee may still be enjoyable and a common consumer may not notice the Taint. If discovered, the coffee may still be considered “specialty” with above 80 points, but the critical question becomes: “can we remove or resolve this taint?” Unless it’s a roaster error, there is little you can do to remove the taint. At that point, many tainted coffees will be dark roasted to cover up slight taint.

A “Fault” will be much more severe. Faults dominate your impression and the cup. They cannot just be roasted out or masked. These coffees will often be sold for commercial and instant coffee use or they may be flavored with chemicals and syrups to mask the extremely unpleasant character they have taken on.

A coffee with soft or subtle traits (following) may be called a “taint” while those with dominant and overbearing traits listed below would be classified as a fault. These include:

• Fermented or Mouldy

• Musty or Rioy

• Earthy or Potato or Raw Peanut

• Unripeness or Greenness

• Hard or Astringent cup

• Woody or Pulpy

• Rubbery or Petroleum

• And more.
  

Pulling it all together.

The coffee industry has the benefit (and at times encumbrance) of long tradition. Coffee growing nations and practices are disperse and disparate across the world. As a result various practices and standards have evolved. While we have learned from one another, we also have formed regional, national and cultural habits around coffee. One of those key factors includes coffee grading and quality measures as they have evolved through language and time.

Due to the wonderful diversity in coffee around the world, we should never judge a fine Chinese coffee from Pu’er in the same manner as a fine coffee from Sumatra, Indonesia. While some aspects will correlate, many will be entirely different. Likewise to judge a Panama Geisha on the same scale as a Kenyan coffee using only one metric is foolish.

If you want to buy a coffee to roast for other people, let’s consider the bigger picture. What are their needs and desires. How can we best serve them?

What qualities will they love in this coffee?

How will they use this coffee?

What price is appropriate for them?

If this was a worthy read, please consider sharing and liking.

Thank You! ~ Adam