Brettanomyces and Saccharomyces Co-fermentation

Funky mixed fermentations, for the purposes of this article, refer to fermentations that contain Saccharomyces and Brettanomyces. They do not contain lactic acid bacteria such as Lactobacillus and Pediococcus. As such, these beers may have a lightly tart flavor, but are not described as being sour (see the Mixed Fermentation page). The flavor of funky beers is often dominated by the array of flavor compounds produced by Brettanomyces (see Brettanomyces metabolism). Generically speaking, these flavors range from tropical fruits, stone fruits, smoke, barnyard animal funk, bitterness that lingers on the palate longer than hop bitterness and is accompanied by undertones of fruit, horse blanket, sweat, body odor, etc.

Brewing Methods

Conceptual graph of dynamics of funk expression and inoculation timing of Brettanomyces. Y-axis for each microbe group depicts relative activity which combines in a conceptual sense: growth, attenuation and production of flavor compounds. Plot drawn by Drew Wham based on concepts discussed in American Sour Beer

Technique	More Funk	Less Funk	Note
Inoculation timing	After Saccharomyces has finished fermentation	At the start of Fermentation	See figure 1
Brettanomyces Inoculation cell count	Lower cell count	Higher cell count	Significantly interacts with the timing of inoculation
Strain of Saccharomyces	Phenol positive strain	Phenol negative strain	Pof+ strains of S. cerevisiae form 4-vinylguaiacol by enzymatic decarboxylation of ferulic acid
Ferulic Acid	More Ferulic Acid	Less Ferulic Acid	A precursor of 4-vinylguaiacol
Time since Inoculation	Aged Beer	Young Beer	References