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====Ester Production====
''Brettanomyces'' is capable of forming synthesizing several ethyl esters (derived from ethanol and fatty acids). Among these are ethyl acetate, ethyl lactate and phenethyl acetate, along with the hydrolysis of isoamyl acetate. During non-mixed fermentations where lactic acid and acetic acid are minimal to none, these esters are produced in smaller quantities <ref>[http://www.brettanomycesproject.com/dissertation/introduction/ Yakobson, Chad]. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Production of Secondary Metabolites. 2011.</ref>.
Ester production peaks towards the end of growth, and is influenced by temperature, aeration/agitation, and pH. One study found that the optimal temperature for growth and thus ester production was 28°C (77°F), although it did not test higher temperatures. This study also found that continuously shaken samples produced relatively less esters, as well as samples that were not exposed to oxygen at all. The highest ester production was found under conditions of limited oxygen supply, not agitated, held at a temperature of 28°C (77°F), and young cells produced more esters than older cells. It also found that esterase activity (esterase is the enzyme that facilitates ester production and destruction) increases as pH rises until a pH of 7.6 is reached, after which it begins to decline again. It was shown that the ester formation/degradation was indeed caused by enzymatic activity of any ''Brettanomyces'' species/strain, and not caused by chemical reactions or from ''Saccharomyces'' or ''Kloeckera'' activity <ref name="Spaepen"></ref>.