In the final part of this three part series we touch on where the idea of brewing and culturing green coffee came from. Exploring sustainable ways of using and processing coffee as a raw plant product was a part of this concept.
Most of my time in coffee was spent working at restaurants and cafes with strong food and beverage programs. Seeing the ways various raw food products can be transformed pushed this idea of trying other processes for coffee other than roasting.
Initially, the green coffee was boiled in water to make what is known as 'green coffee extract' (GCE) without a dehydrating step. The liquid extract tends to be quite bitter and not great tasting by itself, however, there is a lot of complexity to it. Drawing from time spent working restaurant bars, I was curious if this green coffee liquid would open up with a basic cocktail approach by adding something acidic and sweet. The resulting profile reminded me of fermented beverages I've enjoyed in the past, mostly natural wines. The tea-like qualities of the GCE base made me think of kombuchas which are fermented sweet tea; I figured I could forgo the mixology by culturing and it worked.
Steps in this process:
Starting with boiling water ,the green coffee is introduced. The boiled water is important for eliminating any bad bacteria in the coffee and water and other surfaces. This also acts as an extraction point of the green coffee.
In other fermentations like wine and beer, both the grapes and grains used have sugar naturally in them. Green coffee does not have sugar naturally in it, so to feed the culture, a bare minimum is added which the culture in turn mostly breaks down.
Next, the green coffee starter and culture are introduced to the green coffee base, and then we wait.
The yeast and bacteria begin to feed on the green coffee and sugar creating byproducts of acetic acid, CO2 and alcohol (.5 ABV or less).
Once the fermentation is complete, the culture is separated from the green coffee and yeast is strained out to halt any further fermentation. The finished drink is chilled, poured and enjoyed.
Fermentation is an old food processing technique which we are excited to explore in this way in the world of coffee.
Jeremiah&Co