Green Coffee Screens and Why Roasters Care

green coffee sizing / grading screens

available now at: LINK to screens

This is a repost of a former blog, including a new YouTube video below and limited availabilty of hand crafted wooden coffee sieves made in Vietnam. Get yours while they last!

—— former blog post follows ———

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.

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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

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 Improve Coffee Sensory Skills

How do we find “Flavor Notes” in coffee?

Distinguishing: fragrance, aroma, taste and flavor.

How do I improve my sensory skills?

These are 3 of the most common questions I am asked, in and out of the coffee classroom. In this post, we’ll answer these 3 questions while expanding the 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 Sensory Skills Foundations course. Either way, we will learn and grow together!

Read to the end for my in depth YouTube explanation of the Counter Culture Flavor Wheel!

Humans are the “tool” used to evaluate flavor.

Yes, that’s right. Your nose and mouth work in coffee science.

All scientific inquiry (coffee tasting will be our study) begins with asking a clear question. Our question: “What is the flavor of this coffee?” For coffee professionals “flavor” is a loaded word. It encapsulates fragrance (the dry coffee smell) with aroma (the wet coffee smell) with the taste (how the coffee drinks).

Since the human nose, tongue and mouth are the “tools” used to perform this experiment we must understand that the signals produced and translated by your unique nervous system will be subjective in nature. You have a unique upbringing, with unique exposure to food and drink with myriad fragrances and aromas. You have learned to interpret those signals with language. You personally enjoy some fragrances, aromas and tastes in a different way than another coffee fan or professional does. If performed alone, your sensory perception is less trustworthy given these subjective (even unconscious) biases.

Statistical value and strength is added when multiple people smell and taste the same coffee and find agreement about its attributes. A more robust study, provides a greater degree of trust in the results. By sampling coffees across a group of people, we can reduce or remove the individual biases attributed. That’s a good thing and brings us closer to objective measurements. Remember coffee is loaded with countless subtle characteristics. While, we can’t fully declare that there are wrong sensory conclusions, we can identify that some conclusions are less prominent and that others are dominant.

PS. Research has often shown that women are more sensitive to sensory cues. So it benefits your study when the gals and guys together are brewing, cupping, and sharing sharing feedback over the same coffee!

What am I sensing?

1. Olfaction = Smell: the “nose” at work

2. Gustation = Taste: the taste buds at work

3. Taction = Touch: the tongue at work

   We put it all together for a Tasting Note!

Olfaction is Smell

When we bring a dry cup of coffee close to our nose, we begin to smell it’s sweet, floral, fruity, nutty, roasty character. The volatile chemicals bursting from the fresh roasted grounds enter our nose and reach the olfactory bulb. This bulb is filled with sensors that interpret the chemical signals and send electrical pulses to our brain and nervous system. This is how we recognize the difference between peanut butter and smoke or strawberries and fresh cut grass. Each gives off a unique aromatic chemical compound.

Most commonly we think of orthonasal olfaction - smelling things in front of our nose. But another aspect we must bear in mind is retronasal olfaction. When you swallow your coffee, a burst of air rebounds on the back of your tongue and in your throat for a second gust of aroma. That’s why kids who don’t like to eat their vegetables hold their nose before biting and don’t let go until they have swallowed.

Guess what! Those same chemicals are present, roasted into being or roasted (transformed) out of our coffee at various stages. They may emerge only when ground super fresh and disappear after sitting for a few weeks in the bag.

Pro tip: coffee does not taste like strawberries, it tastes like coffee. But some coffee sure has a strong fruity aromatic resemblance with strawberry!

Credit to Wine Folly for this easy diagram. Thanks! https://winefolly.com/deep-dive/science-of-wine-tasting/

Gustation is Taste

“Taste” is a rather broad term. Here we bring it back to its most basic form. The human tongue is a rather simple tool. Used mostly for survival in the process of consuming foods. The sensations of the tongue distinguish (from least sensitive to most): Sweetness, Saltiness, Sourness, and Bitterness. Let’s break these down..

The least sensitive sensation of gustation is sweetness. Many people are able to consume copious amounts of sugar and sweetness without their brain giving warning signals. We neither fear it, nor tire too easily of it.

The next gustatory sensation that is a bit more sensitive is saltiness. While we do enjoy salt (in the right proportions) we cannot tolerate spoon fulls of it, like we can sugar. Too much salt wears down the tongue and causes some adverse side effects if consumed over long periods of time.

Even more sensitive is sourness. This taste sensation begins to turn on our warning lights. As we gustate old-spoiled milk (which was once fresh and sweet) that has become sour we immediately spit it out. Something tells us - this is wrong! Spoiled foods go sour. Drop a splash of white vinegar in your friends water and see what they say. Try again with a pinch of sugar and they likely will not notice.

Humans are most sensitive to bitterness. The last taste is very common to coffee. When someone slides you a REALLY dark roasted coffee you immediately think, “wow! that’s bitter”. Bitterness is present in carbon. Carbon is dangerous for us and many claim it is carcinogenic… thus avoiding grilled foods. Slide a black cup of coffee to a toddler (let’s just imagine ; ) and they’ll immediately spit it out. Bitterness is the taste of caffeine, which is a drug that kids do not accept by taste. Almost every drug from the pharmacy tastes bitter because the chemicals in them are dangerous. Eat a jar of sugar and have an upset stomach. Please don’t eat a jar of pills (or even coffee beans).

Gustation is very very simple. Lao Tzu, in “The Art of War” understood this 2,500 years ago,

“There are not more than five cardinal tastes (sour, acrid, salt, sweet, bitter), yet combinations of them yield more flavors than can ever be tasted.”

PS. “acrid” is like a harsh salt taste. Perhaps this was also an attempt at naming “umami”?

Taction (Tactile) is Touch

The final part of our equation is found in your sense of touch. When we bring the coffee to our lips we feel it’s temperature. This can be pleasant, painful, or disappointing. Next, if it’s not too hot, we feel the coffee on our tongue. It may be heavy (like cream or milk) or it may be light (like tea or water). Perhaps the feeling of the coffee is somewhere between (smooth, rich, silky). We call this mouthfeel and it can be an important attribute on tasting notes or descriptors.

The coffee may coat your tongue in a sticky manner creating a long lasting flavor sensation. Does the flavor linger long or disappear? As you swallow (gustation carried through) the coffee then you may have this combined sensation of aftertaste. This is in part a retro-nasal action, but it is also in part the tactile sensation of your tongue, mouth and throat being coated with coffee.

Pro Tip: when we aspirate and slurp our coffees we accomplish 2 important things.

One - we vaporize the aromas in the coffee for more olfactory stimulation.

Two - we spray the coffee across the mouth for greater taste and tactile sensations.

Now you go try!

Click on image to download from Counter Culture.

How to grow in sensory skills!

If you made it this far, good work. You likely want me to get to the good stuff and tell you the quick and easy way that you can master the art of sensory perception in coffee. Right?

I wish it was as easy as a simple lesson. However, like all good skills - coffee sensory analysis requires practice. But as long as you’re putting in the work - let’s be sure to practice the right things. Here goes:

My list for ways to grow in coffee sensory analysis:

1. Practice smelling and tasting on a light or empty stomach. A full stomach dulls the senses. If you must eat, try a banana, apple or toast.

2. In the same logic as above, test your coffee or perform cupping early in the day. By night time your body and senses are tired and less receptive.

3. Eat and drink more slowly. Chew longer. Drink slowly. These sensory habits will certainly lead to better health habits as well.

4. Get a good night sleep. Make sure you’re not feeling sick. Lack of sleep and sickness often lead to dulled senses and/or upset stomach. If any symptoms like this exist your body will be more focus on healing and preservation than enjoying sensory stimulation.

5. If you have sinus problems or a stuffed nose, do blow it. Having clear sinuses will help you perceive what you smell.

6. Alternatively, do you have a dry nose? Take a cup of hot water and just breath in the warm steam. By warming and wetting your nasal cavity you will increase the sensitivity to aroma and fragrance. This is the same reason a healthy dog has a wet nose and why other dogs will lick their noses - it increases sensitivity to smell.

7. Avoid drinking too much coffee before sensory work. The more caffeine you ingest the less sensitive you are to the next cup of coffee. Your pallet and tongue also become fatigued.

8. Avoid soap or lotions with perfumes. Go perfume neutral and ensure that the room you are in is free of candles or other strong smells.

9. Learn to attend to your senses all day long. As you go through the day you need to catalogue all of the fragrances and aromas you encounter. Sensory analysis works because your brain has a library to draw from. As you record experiences daily - your library grows and you quickly know how to recall and name what you sense. Every moment can lead you to mastery. Read on:

10. Daily Olfaction: When you walk into a new room, stop to notice the fragrances present. It is hairspray or perfume? Old furniture or leather? Etc. When you eat a meal, every meal, stop and ask what am I really smelling? Can I recognize any spices or seasonings?

11. Daily Gustation: Isolate flavors in your drinks. How sweet or sour are they? Are there different levels and combinations of taste sensations? When you drink water is it slightly salty or sweet (perhaps mineralized) or do you recognize odd taints in it (like in city water)?

12. Try reducing or eliminating sugar for a few days. After it has been removed, slowly reintroduce it in small amounts. You will find your sensitivity has increased. Do the same for salt if you have a high salt diet. I did this in China for a few weeks. I ate plain boiled oats for breakfast. I cut out all soda, snacks and sugary treats. Later adding just a few raisins to my oats made me feel like a king! : )

13. Isolate sensations. When you know what sugar feels like (not tastes like) then find that feeling in a nice light roasted black coffee. Recognize sour in a lemon and then find it in your light roast. If your grocery store has tonic water get some unsweetened. Or if you have an Asian market nearby, look for bitter melon (it looks like a long bumpy cucumber). Once you can isolate sensations, then you can also recognize them when stirred together. When you have a sweetened tonic water you can taste the sweet and bitter at work together on your tongue.

14. Plan extra time at the grocery store. Spend 15 minutes in the produce section smelling the vegetables. Fruit and veggies have great attributes you can smell (especially if organic and fresh). Try the live spice section. Then head over to the dry spice section and bulk food section. Smell and categorize everything, but be discrete of course ; )

15. Use a Coffee Tasters Flavor Wheel. The New SCA Flavor Wheel, the Old SCA Flavor Wheel and the Counter Culture Flavor Wheel are all super useful and you can grab them via these links. Work from general to specific - from inside to the outside. For example when a coffee smells sweet is it floral or chocolate or fruit sweet? You identify it’s like fruit so is it a red fruit or tropical fruit or citrus fruit. It’s a citrus fruit sweetness. Maybe you just stop there with your tasting notes. Well Done! Or perhaps you go further and say, it’s a little sweet and tart like a grapefruit. Lemons are not so sweet, but oranges are far too sweet. Perfect! Using process of elimination working from general to specific is the way to go.

16. Try the rigorous experiments in the Coffee Lexicon by the World Coffee Research, or head back to the the grocery store. Perhaps it’s time to pick up some milk chocolate, dark chocolate and bakers chocolate… for scientific research of course ; ) While you’re at it grab a good variety of unroasted and unsalted nuts if available from the bulk section.

17. Finally, have fun. Don’t compare yourself to “the pros”. Many coffee people (myself in the past) may feel bold and make great declarations about wild tasting notes. Just say, “oh that’s nice. I don’t taste marmalade and sassafras root, it’s just sweet and spicy to me.” Perfect! Smile and keep honing your skills.

A joyful brain is a growing brain.

Enjoy the Sensory Journey my friends! If you’d like to learn more and try getting certified with the Specialty Coffee Association, then I developed a course for you!

Insert plug with link for Sensory Foundations course : )

Let’s Review.

How do we find “flavor notes” in coffee?

How do we differentiate all that goes into a “flavor note”?

And, how do we grow in our coffee sensory skills?

If you can’t answer, or begin to practice, these 3 above then please reach out and let me know what questions you have. I enjoy hearing from friends and students in my courses and look forward to helping you on the path to coffee mastery.

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

Thank You! ~ Adam