How Process Impacts Brew

Recently, we held a class on Processing with the cool folks at Kick Ave. Coffee Supply in Columbia, SC. If you aren't familiar, Kick Ave might just have the best selection of multi-roaster whole bean specialty coffee in all of South Carolina. Their space is outfitted with a wall of incredibly talented roasters and high quality beans from all over the world. They've got everything from approachable and easy-to-brew to funky, wild, and rare! Beyond the selection of coffee, they are also purveyors of an array of coffee brewing equipment, gear, and education. It's a one stop shop. 



But how do you choose which coffee or new dripper to take home? The best part of their shopping experience is the people - Their team will welcome you in like old pals, walk you through selections, and even offer a guided tasting experience at their pour over bar where you can sample what's being featured or learn about a particular brewing method. To amplify this guided experience and share deeper level brewing recommendations with their community, we joined them to talk about how processing, roast level, and origin might impact the end of cup flavor and how one might approach brewing for the first time.

Here are some of the concepts we covered:

1. Coffee is a fruit and fruit is a dynamic product with a lot of variation

Farm to farm, lot to lot, harvest to harvest, seed to seed. Within that variation, there are dozens (if not, hundreds) of decisions to be made from seed to cup that will impact how a coffee extracts and behaves. That means there aren't perfect hard rules that apply to all of one type of coffee - washed, natural, or otherwise. There will always be coffees that make exceptions to any rule we try to create around flavor and brewing.

2. Processing and fermentation have large impacts on determinant flavor.

How green coffee is dried plays one of the most significant roles in the unique character, aroma, and chemical composition of coffee beans. While characteristics are linked to variety and to the origin or "terroir" of coffee, we know that changes in processing methodology and environment induce different metabolic reactions in coffee fruits.

Fermentation is a metabolic process that uses sugar, either in the absence (anaerobic) or presence (aerobic) of oxygen; and coffee fermentation is an effective step for removing the fruit layer from the parchment covered seed. The fermentation process is facilitated by enzymes that naturally occur in the coffee fruit and from the microflora acquired from the environment. Microorganisms (yeast, bacteria, and fungi) work with these intracellular enzymes to degrade mucilage with byproducts of various extracellular enzymes, esters, aldehydes, ketones, alcohols, organic acids, etc.

It is important to note the goal of producing and drying coffee for every producer is not always a particular flavor or even a certain quality. 

3. Variation in processing affects bean density .

Green density affects roasting. Post roast density affects brewing.

 Other factors affecting green coffee bean density include:

• Growing altitude (higher altitude = denser beans)
• Processing method (washed coffees tend to be denser)
• Variety (some varieties naturally produce denser beans)
• Storage conditions and age
• Soil composition and fertilization practices
• Annual rainfall and irrigation patterns

For roasted coffee, lighter roasts will be more dense than darker roasts. The more dense the roasted coffee, the harder we need to work to extract solubles through a less porous material. This could mean adjustments like grinding finer, longer pre-infusions, extending contact time, or increasing brewing temperature.

4. There are some generally associated flavors with processing methods. The 3 major categories are:

• Natural - Coffee is dried with skin and fruit on the seed. Common expectation in high quality cups: sweet, fuller body, deep ripe or stewed fruits, milder acidity
• Semi-wash/Honey - Coffee is pulped and dried with some % of the fruit left on the seed. They can showcase a wide range of flavors but typically you can expect less intense fruit than a Natural but a more syrupy body, nuttiness, and sweetness than a washed coffee. 
• Washed - Coffee is dried in parchment and the fruit has been removed. These tend to be described as clean, bright, citric, crisp with a lighter body and more apparent acidity. Can have varying levels of fruitiness or traditional chocolatey, nutty profile.

Check out the quick guide of commonly used terms in processing here. < Cafe Imports site is easy to digest and has a lot of visuals and videos that you can reference as well. For the coffee nerds..Christopher Feran has an epic glossary of sorts.

5. Most everything else is a manipulation

or some additional step added to one of the above broader categories. Drying can be slowed or sped up. Microbiomes can be changed. Environments can be managed. Access to advanced tools and technology can shape control and consistency.

6. Roasting shapes inherent flavors.

Very simply, let's imagine flavor manipulation in reference to a pineapple.

• Underroasted might be like an under ripe pineapple: vegetal, green, too high acid
• Light roast might be like a fresh, juicy pineapple: high but balanced acid, fruity, juicy, complex
• Med roast might be like a cooked/sauteed pineapple: lower acid, fuller mouthfeel, sweeter/caramelized
• Dark roast might be like a chargrilled pineapple: elements of char, bitter, very low acid, high sweet, syrupy
• Heavily roasted: char, ash, smoke, fire, no longer resembles pineapple

6. Some Patterns

• Washed Coffees - can typically handle higher temps and finer grind settings. Likes higher contact times. Natural may not need quite as high contact time.
  
  
• Washed Ethiopia  - Particularly higher fines production - common with high grown, hard beans that are very dense. African coffees also tend to contain higher soluble content. 

  
  Check out this chart from Barista Hustle on the impact of origin and varietal on brew time or read more here

   

  
• Pink Bourbon, Ethiopia Heirloom, Gesha - Varieties we see benefiting from longer pre-infusions where applicable to make them more soluble. I personally prefer larger brew ratios with coarser grounds to draw out extraction and complex flavors without too much contact time. These also benefit from longer rest times post roasting.
  
• Anaerobics, Carbonic Maceration, Coferments, Thermal Shocks - tend to experience 'booziness' or astringency at very high extractions. We have fun with these at a variety of strengths. These coffees tend to have red wine-like acidity, intense aromatics, and complex fruitiness. They are sometimes funky and insane tasting. When done without experience or controls, they can turn out very sour or over-fermented, with a muddy character.
  
  
• Dark Roasts - Very brittle - can also create a lot of fines. Less soluble material. Extracts quickly. Needs lower contact times. Does well with stronger brew ratios. Will have more CO2 build up but will stale quicker and will need shorter rest times.

7. How coffee is ground and brewed will shape how we perceive a coffee quality and can easily make a great coffee taste terrible.

Under-extracted coffees will lend to very sour, sharp, and intense tactile sensations, whereas over-extracted coffees will lend to hollow, ashy, drying, astringent "over-steeped tea" character. Unevenly extracted coffee will have both tactile qualities and may feel chaotic on the palate. Something as simple as your water quality will vastly influence how your coffee extracts.

A final takeaway
Coffee is complex and making a perfect cup isn't as simple as it looks! There is no wrong style of coffee and we encourage you to try different kinds of beans, origins, processes, roast levels, and even roasters (with the vast world of coffees out there, we shouldn't be your only supplier ever). Over time, you'll come to recognize coffees that work for you with your set of supplies, time constraints, and preferences. And while this is in no way your complete guide to brewing or purchasing coffee, we hope some of the insights above can help you make more informed decisions on your coffee journey.