13,591
edits
Changes
Added an Acid table
| Phenethyl acetate (Sweet, Honey, Rose flower like) || Acetyl-CoA, 2-phenylethanol || 3-5ppm (odor), 5-10ppm (flavor) <ref>[https://books.google.com/books?id=A8OyTzGGJhYC&pg=PA1521&lpg=PA1521&dq=Phenethyl+acetate+flavor+threshold&source=bl&ots=Ygvq_JFvhQ&sig=06Lj57fWYemcXizkEHnYzwfOXX8&hl=en&sa=X&ei=Zz-nVOPCKI61oQSFwIGABQ&ved=0CEAQ6AEwBA#v=onepage&q=Phenethyl%20acetate%20flavor%20threshold&f=false Burdock, George A]. Fenaroli's Handbook of Flavor Ingredients, Fifth Edition. CRC Press. 2005. pg 1521. </ref> || <ref>[http://www.ymdb.ca/compounds/YMDB00574 YMDB]. Phenethyl acetate.</ref>
|-
| Ethyl butyrate (Pineapple) || [[Butyric Acid]] || || Low levels of production by some species of Brettanomyces; production decreases with higher acidity <refname="yakobson1">[http://www.brettanomycesproject.com/dissertation/pure-culture-fermentation/pure-culture-fermentation-discussion/ Yakobson, Chad]. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Pure Culture Fermentation Discussion. 2011.</ref>
|-
| Ethyl Decanoate (Brandy, Fruity, oily, Grape) || Capric Acid (Decanoic acid)|| || Also known as Ethyl Caprate <ref>[http://www.michiganbrewersguild.org/docs/Gary-Spedding_off-flavor-notes_2014WC.pdf Spedding, Gary. Flavor notes for Michigan Craft Guild Conference. 2014.]</ref>
==Acid Production==
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.
{| class="wikitable sortable"
|-
! Acid !! Precursors !! Notes
|-
| Acetic Acid (Vinegar, harsh acidity) || Oxygen || Increased production with higher levels of oxygen exposure.
|-
| [[Isovaleric Acid]] (Feety, Rancid parmesian) <ref>[https://scholar.sun.ac.za/bitstream/handle/10019.1/4141/Botha,%20J.J.pdf?sequence=1 Botha, Janita J. Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African wines. March 2010. Pg 2, 13, 17, 18]</ref><ref>[https://scholar.sun.ac.za/bitstream/handle/10019.1/1239/oelofse_investigating_2008.pdf?sequence=1 Oelofse, Adriaan. Investigating the role of Brettanomyces and Dekkera during winemaking. December 2008.]</ref>|| Leucine || Commonly described as a "spoilage" acid produced by Brettanomyces in wine, but also appears in beer.
|-
| Caproic acid (Fatty, cheesy, waxy, barnyardy) <ref name="yakobson1"></ref>|| || Fatty acid.
|-
| Enanthic acid (Rancid odor) <ref name="yakobson1"></ref>|| || Fatty acid.
|-
| Caprylic acid (Rancid-like smell and taste <ref name="yakobson1"></ref>|| || Fatty acid. Also found in milk.
|-
| Pelargonic acid (Rancid odor) <ref name="yakobson1"></ref>|| || Fatty acid.
|-
| Capric acid (Barnyard animal odor/taste) <ref name="yakobson1"></ref>|| || Fatty acid. Also found in milk, coconut oil, and seed oils <ref>[http://en.wikipedia.org/wiki/Decanoic_acid "Decanoic acid". Wikipedia.]</ref>.
|-
| Undecylic acid <ref name="yakobson1"></ref>|| || Fatty acid.
|-
| Lauric acid (faint odor of bay oil or soap) <ref name="yakobson1"></ref>|| || Fatty acid.
|}
=Brett Strains=