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====Introduction====
While most beer styles are fermented using one culture of ''Saccharomyces cerevisiae'' or ''S. pastorianus'', Flanders Red Ales are fermented with a [[Mixed Fermentation|mixed culture fermentation]]. At one brewery (presumed to be Rodenbach) studied by Martens et al., two beers were produced using mixed fermentation and blended together. The first "light beer" was 11°P and was less acidic, while the second "heavy beer" was 13°P and served unblended as an Old Ale. Both beers were inoculated with an acid washed yeast slurry that was harvested from a previous fermentation of the "light beer". The yeast slurry contained about 5% lactic acid bacteria after the acid wash. The fermentation of these beers had three stages:
#. A seven day ethanol fermentation dominated by ''Saccharomyces''. #. A four to five week lactic acid fermentation dominated by ''Lactobacilli''. #. A twenty to twenty-four month fermentation dominated by ''Brettanomyces'', ''Lactobacilli'', ''Pediococcus'', and acetic acid bacteria (''Acetobacter'').
The development of the third stage with ''Brettanomyces'' and ''Pediococcus'' was similar to the development of these microbes in [[Lambic]] fermentation. The "light beer" was never allowed to go through the third phase of fermentation, and was instead chilled to 0°C and then used to blend with previous batches of the "heavy beer" <ref name="Martens">[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1997.tb00939.x/abstract MICROBIOLOGICAL ASPECTS OF A MIXED YEAST—BACTERIAL FERMENTATION IN THE PRODUCTION OF A SPECIAL BELGIAN ACIDIC ALE. H. Martens, D. Iserentant andH. Verachtert. 1997.]</ref>.