#4: Over Fermentation and Brettanomyces

I find the term "over fermentation" to be especially annoying. From a biology point of view this term is nonsense.

When coffee professionals use this term it's understood to mean a defect, usually vinegar, "boozy" or like rotting fruit. Everyone agrees that it's a negative trait for a coffee to have. I think it's important to be able to identify this trait but I think this label has held fermentation back and made many (producers and roasters alike) shy away from a process that when controlled can enhance coffee quality.

In this week's episode I answer a listener question about double fermentation and Brettanomyces that gives me an opportunity to untangle the concept from the name we've given it.

"Double fermentation" is another common colloquial phrase mistaken for a scientific label.

It gives the impression that there are two fermentations, but this is not what's happening biologically.

I also talk about the Russian River Brewing Company in Windsor California. I visited earlier this year in July and got to see how they use Brettanomyces and try their Brett Beer. The coffee industry is borrowing from the Beer industry as well as the wine industry and beer yeasts are becoming more popular in mills across Central America. This is an exciting time for coffee microbiology but there are a few cautions I want to give about this particular yeast.

For the visually inclined: I have 3 videos that will breakdown the coffee fermentation process:

https://www.luxia.coffee/instructional-videos