Innovative Processing Discussion - Anaerobic, Honey, Carbonic Maceration
The words Anaerobic and Carbonic Maceration did not exist in the specialty coffee industry until about five years ago. In my world, they did not exist until this past year. My own "pandemic special" if you will. It took me a long time to understand the difference in processing of these coffees and what it means for flavor development. I am in no way teaching this information from personal experience. Rather, I am sharing what I've learned based on educational materials provided by the very best green coffee importers and producers in hopes that this information can also be a helpful resource to understand the story behind each coffee we drink.
ANAEROBIC
I have tossed the term anaerobic around in a pretty nonchalant way in this subscription without really explaining the meaning and impact this has on the future of specialty coffee. Basically there is an added step to the typical Washed/Natural/Honey process to yield an Anaerobic process - sealing the coffee in a tank to cut off oxygen.
In the "Washed Anaerobic" process, the coffee cherries are depulped of all cherry and mucilage in the normal washing process. The coffee would then be sent to fermentation tanks in an open environment for 18-36 hours (generally), and then "washed" with turbulent water to remove all mucilage. The difference in Anaerobic would be the post-depulp stage. Rather than having an open fermentation tank like with a normal washed processing, the tanks (plastic, stainless steel, etc.) are hermetically sealed to prevent air from coming in. Next is where it gets interesting - the depulped mucilage is gathered, packed together, and then spread across the coffee seeds till evenly coated. Once sealed, the oxygen in the tank is diminished by the Carbon Dioxide production.
The time spent in sealed fermentation tanks is completely up to the producer and what they are trying to do. I have seen some for 18 hours and some for 400 hours at colder temperatures. The reason these coffees are so vibrant and delicious is from the flavors of the cherry being directly injected in the coffee seed due to cherry skin-contact during this oxygen-free environment. The control of pH, sugars, temperature, and yeast production is easily observed because of the smaller batch sizes. This extra effort is why we typically find these coffees to be a little more expensive.
Alternatively, there is a "honey style" of anaerobic processing. The small difference here is that the coffee seeds are sent in to the tanks without depulping all of the mucilage. Since I brought it up, I figure I should explain why this is honey style, by giving a brief overview of honey processing.
HONEY
Honey processing includes four different colors: White, Yellow, Red, and Black. Each color in this order corresponds to a different level of seed-in-cherry fermentation. These coffees when done correctly have an excellent marriage of sweetness, clarity, and fruit.
The different colors mean something different as far as standards go in every country of origin. In general, white honey means mostly all mucilage is removed during depulping stage, yellow has slightly less mucilage removed, and so on. Additionally, black and red honeys have an extended fermentation time to create even more fruity flavors in the coffee. Black honeys are fermented the longest, and therefore require the most monitoring to prevent over-fermentation.
To answer the obvious question; no. There is no actual honey involved. The use of the word honey refers to the stickiness of the seed following fermentation with the mucilage remaining on the seed. The stickiness level of the seed is developed through the most important stage of honey processing - the drying. If honey processed seeds are dried too quickly, the seed won't have enough time to absorb the mucilage flavors. If they are dried too slowly, the coffee bean risks over-fermentation.
To find the balance in fermentation, the raking of the seeds on raised beds in the open air is extremely important. This control of the drying rate is what makes this an innovative process. The desirable flavors of natural process coffees are present, while minimizing the risks of over-fermentation.
CARBONIC MACERATION (CM)
CM is a highly controlled, intricate version of Anaerobic processing. The process was developed by a famous coffee person named Sasa Sestic from Australia. Sestic worked closely with wine-makers who utilize this technique regularly, and particularly with a Colombian producer named Camilo Merizalde.
When I first asked what this process meant, I thought it was just a pretentious way of saying it is Anaerobic. Turns out, it is in fact a nerdier version of Anaerobic. All the steps are followed after the depulping stage (or lack thereof in the case of a natural Anaerobic) and tank sealing. However, instead of the fermentation process letting the Carbon Dioxide consume the Oxygen in the tank, the tank is flushed with Carbon Dioxide at the very beginning, allowing the producer to completely control the amount of yeast, bacteria, fermentation, pressure, and temperature in the tank.
The result is an intensely fruity yet clean brew. The coffee tastes pristine. However they are not cheap due to the cost of materials, labor, and the experience in coffee processing required for the proper fermentation. I hope to share a CM coffee with the subscription soon, as I would love for everyone to taste what I consider the most progressive processing technique the world has to offer right now.
Thank you to everyone for reading/skimming this information. The test is next Tuesday.
Just kidding, but I do hope if people were confused on what these processes mean, they can find clarity in my explanation. As mentioned above, this information is not entirely derived from my own personal knowledge, so here is a list of sources I used to gather this information:
https://blog.genuineorigin.com/2018/07/31/anaerobic-process-new-flavors-innovation/
https://projectorigin.com.au/cm-selections/
https://www.lacabra.dk/products/los-pirineos-semi-carbonic-maceration-petites
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