Why do we taste Vinegar and Rusted Metal characters in coffee?
The problem with traditional fermentation is that we do not control temperature during fermentation.
Temperatures from day and night change, as temperatures day by day change; this will effect how fast we are breaking down sugars from mucilage. This will directly impact consistency of coffee and also flavour complexity.
So for example, in the picture on left – we have fermented this coffee for 24 hours at average temperature of 16 degrees Celsius. This coffee tasted great, nice and balanced.
In the picture on the right, we also fermented this coffee for 24 hours but at 26 degrees, so 10 degrees higher than the other.
You can see the pink line through middle of the parchment – this happens when we spend way too much time fermenting coffee and alcohol acidic acidity starts dominating fermentation. This results in notes of vinegar, as well as dry and metal characters. I am sure you have tasted this in coffee before.
More results to come soon!