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Glycosides are sugar molecules connected to other organic compounds such as acids, alcohols, and aldehydes which are flavor and aroma inactive due to the sugar molecule attached. By cleaving off the sugar molecule through glucosidase activity, ''Brettanomyces'' species can liberate these compounds (called aglycones) into their aroma-active and flavor-active states, or states that may become flavor and aroma active through further modification<ref>Daenen et al., 2008. Evaluation of the glycoside hydrolase activity of a Brettanomyces strain on glycosides from sour cherry (Prunus cerasus L.) used in the production of special fruit beers. FEMS Yeast Res. 8, 1103-1114.</ref>. Therefore ''Brettanomyces'' strains are able to produce novel flavors and aromas from hops, fruits, and fruit pits that ''Saccharomyces'' yeasts cannot produce. In addition, the liberated aroma and flavor active compounds may be further processed by ''Brettanomyces'' through ester production or destruction pathways.

''Brettanomyces'' is capable of forming 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>.

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Phenols such as 4-vinylphenol (4VP, barnyard, medicinal) and 4-vinylguaiacol (4-VG, clove) can be produced in beer by the decarboxylation of hydoxycinnamic acids, which are found in malt. While both ''Saccharomyces'' and ''Brettanomyces'' strains are capable of converting hydroxycinnamic acids to their vinyl derivatives, ''Brettanomyces'' is also able to reduce these vinyl derivatives to ethyl derivatives. These vinyl derivatives have similar tastes to the ethyl derivatives but have lower flavor thresholds.

fermentations with respect to time. Presentation at 2008 NHC. pg 12.</ref> <ref>[http://www.mbaa.com/districts/michigan/events/Documents/2011_01_14BrettanomycesBrewing.pdf Yakobson, Chad]. Brettanomyces in Brewing the horse the goat and the barnyard. 1/14/2011</ref>

In the presence of oxygen, ''Brettanomyces'' strains are capable of producing acetic acid. Depending on the brewer's palate and the degree of acetic production, this can be a desirable or undesirable trait. The degree of acetic acid production varies among different ''Brett'' strains. Acetic acid produced by ''Brettanomyces'' may also be used in the synthesis of [[Secondary metabolites|acetate esters]] such as ethyl acetate. ''Brett'' has been shown to produce enough fatty acids in anaerobic fermentation to drop the pH to 4.0, which can also be esterified (see the ester table above) <ref name="yakobson1"></ref>. Many of these acids can have an unpleasant rancid odor and/or taste, which may be noticeable in young ''Brettanomyces'' beers before these acids are esterified.

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