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Key flavor compounds were analyzed for the different fermentations. Overall, the results showed that some flavor compounds produced by ''S. cerevisiae'' remained even when co-fermented with ''Brettanomyces'' (either co-pitched, or staggered pitch), indicating that the strain selection for ''S. cerevisiae'' for a co-fermentation remains important for the final flavor profile of the beer. It is also possible that since this experiment was only conducted for 21 days that the ''Brettanomyces'' did not have enough time to have its full flavor impact. In general, there were no significant flavor differences between the co-pitched fermentations versus the staggered pitch fermentations (despite there being a very significant attenuation difference as previously mentioned) <ref name="Tyrawa_Masters" />.
The ester profiles of the co-fermentations (both the staggered and co-pitch) were a little bit subdued compared to the primary fermentations with ''Brettanomyces'', indicating that primary fermentations with ''Brettanomyces'' produces higher amounts of esters versus co-fermentation of ''Brettanomyces'' with ''S. cerevisiae''. For example, lower levels of ethyl caproate, ethyl butyrate, ethyl caprylate, ethyl decanoate, ethyl nonanoate, and ethyl lactate, were seen in the co-fermentations versus the ''Brettanomyces'' primary fermentations with some of these compounds dropping below flavor threshold levels (ethyl caproate, for example) . The ester production of ''Brettanomyces'' peaked at 14 days, and then esters slowly degraded. In the co-fermentations, the ''Brettanomyces'' appeared to be degrading acetate esters produced by the ''S. cerevisiae'', such as phenyl ethyl acetate, and producing higher amounts of of ethyl acetate. Phenol production began as soon as ''Brettanomyces'' was pitched, and this has been hypothesized to play a large role in replenishing NAD<sup>+</sup> to alleviate the initial lag growth phase in ''Brettanomyces''. Interestingly, levels of 4-ethylphenol were slightly lower in the 100% ''Brettanomyces'' ferments versus the co-fermentations with ''S. cerevisiae'', indicating that perhaps 100% ''Brettanomyces'' fermentations produce slightly less phenols <ref name="Tyrawa_Masters" />.
==See Also==