Brettanomyces
Brettanomyces, also known as Brett or Bretta, is a yeast that was originally thought of as a spoilage yeast. The genus name Dekkera is used interchangeably with Brettanomyces, as it describes the teleomorph or spore forming form of the yeast [1]. Known for it's barnyard, fecal, horsey, metallic or Band-Aid flavors, Brett was unwelcome in most breweries. However, in some styles like Saison and Lambic these flavors add a layer of complexity to the beer. Brett can form a pellicle. See Lactobacillus, Pediococcus, Saccharomyces, and Mixed Cultures charts for other commercially available cultures.
Contents
Brettanomyces Metabolism
Carbohydrate Metabolism
Brettanomyces strains may possess both alpha and beta glucosidases. These enzymes allow Brettanomyces strains to break down longer chain carbohydrate molecules and to liberate glycosidically bound sugars which are unfermentable to Saccharomyces yeasts.
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[2]. 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.
Secondary Metabolites
Secondary metabolites are compounds that are not essential to the life of an organism [3]. Brettanomyces will use a range of secondary metabolites to produce many of the fruity and funky esters, phenols, and acids that this genus of yeast has become known for.
Ester Production
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 [4].
Ester | Precursors | Flavor/Odor Threshold | Notes |
---|---|---|---|
Ethyl acetate (fruity, solventy) | Acetic Acid | 33ppm (odor), 100ppm (flavor) | High flavor threshold; pear-like in low amounts and nail polish in high amounts. Increases production with higher temperatures and oxygen |
Ethyl lactate (fruity, buttery) | Lactic Acid | 0.2 ppm-1.66 ppm (odor) [5] | Increases production with higher amounts of Lactic Acid |
Phenethyl acetate (sweet, honey, rose flower like) | Acetyl-CoA, 2-phenylethanol | 3-5ppm (odor), 5-10ppm (flavor) [6] | [7] |
Ethyl butyrate (pineapple, mango [8]) | Butyric Acid | 0.4ppm (flavor) [9] | Low levels of production by some species of Brettanomyces; production decreases with higher acidity [10] |
Ethyl Decanoate (brandy, fruity, oily, grape) | Capric Acid (Decanoic acid) and ethanol [11] | Also known as Ethyl caprate, Ethyl caprinate, and Capric acid ethyl ester [12] | |
Ethyl caproate (sweet, fruity, pineapple, banana, apple or aniseed) | Caproic acid [13] | 0.2ppm (flavor) [14] | Also known as Ethyl hexanoate, Ethyl butyl acetate, and butylacetate [15] |
Ethyl caprylate (Sweet, waxy, fruity and pineapple with creamy, fatty, mushroom and cognac notes [16]) | Caprylic acid (contained in buckwheat; produced by yeast autolysis) and ethanol [17] | 15ppb (flavor) [18] | Also known as ethyl octanoate |
Isoamyl Acetate (banana) | Acetic acid, Isoamyl alcohol | 1.1ppm (flavor) [19] | Produced by certain Saccharomyces strains but concentrations are generally reduced by Brettanomyces. [20] |
Phenol Production
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.
Phenol | Phenol Type | Precursors |
---|---|---|
4-vinylphenol (Barnyard, Medicinal, Band-aid, Plastic) | Vinyl phenol | P-Courmaric Acid |
4-vinylguaiacol (Clove) | Vinyl phenol | Ferulic Acid |
Vinyl catechol (Plastic, Bitter, Smokey) | Vinyl phenol | Caffeic Acid |
4-ethylphenol (Barnyard, Spicy, Smoky) | Ethyl phenol | 4-vinylphenol |
4-ethylguaiacol (Smokey, Spicy, Clove) | Ethyl phenol | 4-vinylguaiacol |
Ethyl catechol (Band‐aide, Medicinal, Barnyard) | Ethyl phenol | Vinyl catechol |
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 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) [10]. 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.
Acids Produced | Precursors | Notes |
---|---|---|
Acetic Acid (Vinegar, hard boiled egg) | Oxygen | Increased production with higher levels of oxygen exposure [10]. |
Isovaleric Acid (Feety, parmesian) [23][24] | Leucine | Commonly described as a "spoilage" acid produced by Brettanomyces in wine, but also appears in beer. |
Caproic acid (Fatty, cheesy, waxy, barnyardy) [10] | Fatty acid. | |
Enanthic acid (Rancid odor) [10] | Fatty acid. | |
Caprylic acid (Rancid-like smell and taste [10] | Fatty acid. Also found in milk. Gives a waxy/oily mouthfeel. Flavor is more intense at low pH levels. Also called octanoic acid.[25] | |
Pelargonic acid (Rancid odor) [10] | Fatty acid. | |
Capric acid (Barnyard animal odor/taste) [10] | Fatty acid. Also found in milk, coconut oil, and seed oils [26]. | |
Undecylic acid [10] | Fatty acid. | |
Lauric acid (faint odor of bay oil or soap) [10] | Fatty acid. |
Other Compounds
Compound Produced | Precursors | Threshold | Notes |
---|---|---|---|
Tetrahydropyridine (cheerios, mousy, urine, cracker biscuit) | L-Lysine, ethanol, and oxygen | See the Tetrahydropyridine page for more details. Classified as a ketone [27]. |
Commercial Cultures
Pure cultures. In cooperation with Funk Factory.
Brewing Science Institute
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Brettanomyces bruxellensis | Medium intensity Brett character. Classic strain used in secondary fermentation for Belgian style beers and lambics. | Same as White Labs. Pro-Brewers only. |
Claussenii | Dekkera anomala | B. claussenii | Brettanomyces clausenii | Low intensity Brett character. | Same as White Labs. Pro-Brewers only. |
CMY1 | Dekkera bruxellensis | B. bruxellensis CMY1 | bsi | Chad Yakobson's mutation of BSI Drie. Pro-Brewers only. | |
Drie | Dekkera bruxellensis | B. drei | Brettanomyces bruxellensis var. Drei | Highly aromatic brett strain. Sourness takes extensive aging to produce | Isolate from Drie Fonteinen; Pro-Brewers only. |
Lambicus | Dekkera bruxellensis | B. lambicus | Brettanomyces lambicus | High intensity Brett character. Know to produce the “horsey” aroma characteristic of Brettanomyces yeast. Classic strain used in secondary fermentation for Belgian style beers and lambics. Same as White Labs. | Pro-Brewers only. |
East Coast Yeast
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Anomala | Dekkera anomala | B. intermedius | ECY-04 | strong ester profile with some light funk and acidity | beer - Adelaide, Australia |
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | ECY-05 | funky with barnyard notes accompanied by some fruit | isolated from Belgian stout |
Custersianus | Dekkera custersiana | B. custersianus | ECY-19 | light fruit and hay | Bantu beer brewery, South Africa |
Farmhouse | ? | B. fantome | ECY-03b | Fruity and funky profile with some acidity gradually increasing over time. Aeration has more of a muted effect | Isolate from Fantome. May not be Brett as per Lance Shaner on MTF. |
Naardenensis | Dekkera naardenensis | B. naardenensis | ECY-30 | strawberry, honey, ripe fruit with a tart, citrusy acidity after 6mo of aging | Isolated from Dr. Pepper |
Nanus | Eeniella nana | B. nanus | ECY-24 | spicy, saison-like profile | bottled beer - Kalmar, Sweden |
GigaYeast
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Brussels Bruxellensis GB001 | Produces classic Brett “Barnyard” characteristics plus some subtle fruity aroma and moderate acidity. Adds a tart complexity to any beer. | |
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Tart Cherry Brett GB002 | Produces some Brett Barnyard funk plus stone fruit and cherry-like esters. This Strain also produces a moderate amount of acid that adds a tart complexity to the brew. | |
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Sweet Flemish Brett GB144 | Produces a sweet, slightly fruity profile with just a hint of barnyard and spicy phenolics |
Omega Yeast Labs
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Claussenii | Dekkera anomala | B. anomala | Brettanomyces claussenii OYL-201 | Contributes more Brett aroma than flavor. Fruity, pineapple like aroma. Flocculation: low, Attenuation: 70-85%, Temp: >85°F, Alcohol Toelrance: medium-high, compares to WLP645. Pro brewers only. | |
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Brettanomyces bruxellensis OYL-202 | Medium intensity Brett character. Classic strain used in secondary fermentation for Belgian style beers and lambics. Flocculation: low, Attenuation: 70-85%, Temp: >85°F, Alcohol Tolerance: medium-high, compares to WLP650. Pro brewers only. | |
Lambicus | Dekkera bruxellensis | B. lambicus | Brettanomyces lambicus OYL-203 | This strain has been described as producing horsey, smoky and spicy flavors. As the name suggests, this strain is found most often in Lambic style beers. Flocculation: low, Attenuation: 70-85%, Temp: >85°F, Alcohol Tolerance: medium-high, compares to WLP653. Pro brewers only. |
RVA Yeast Labs
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | RVA 502 | A medium-intensity Brettanomyces yeast strain. Will add a bit of funk when added during the secondary. Typically used in Belgian-style beers, especially lambic. A famous Trappist brewery produces its unique beer with this yeast during secondary fermentation. | |
Claussenii | Dekkera anomala | B. claussenii | RVA 501 | A low-intensity strain. Contributions from this strain are mostly aromas of pineapple and fruit. This strain prefers higher temperatures (85º F), but will produce nice aroma and subtle flavor at normal ale fermentation termperatures (68-72º F). | |
Lambicus | Dekkera bruxellensis | B. lambicus | RVA 503 | High-intensity “Brett” strain. Very spicey with “smoky” and “horseblanket” flavors and aromas. This strain is used mostly in Lambics and Flanders sour beers. | |
Unknown | Unknown | Unknown | RVA 804 | Produces some amazing aromas of pears, and other fruit esters. We highly recommend this strain for Belgian Dubbels. This strain also makes a very nice cider. A highly flocculating, medium-high attenuating strain adds nice complexity to stouts, and Belgian Ales and Specialty Belgian Ales. Flocculation: Medium, Attenuation: 78-85%, Suggested Temp Range: 65-72°F, Alcohol Tolerance: 14%. | This strain originates from local fruit trees. |
White Labs
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | WLP650 | Barnyard | Not the same as WY's Brux |
Bruxellensis | Dekkera bruxellensis | Brettanomyces bruxellensis Trois Vrai | WLP648 | Pear | The vrai (true, in French) Brettanomyces bruxellensis Trois. The infamous strain used for all-Brettanomyces fermentations, has a robust, complex sour character with aromas of pear. Best used as a primary fermentation strain. May be the same as BSI Drie? Profile is very similar to BSI Drie [28] [29]. |
Claussenii | Dekkera anomala | B. claussenii | WLP645 | Fruity, pineapple | |
Lambicus | Dekkera bruxellensis | B. lambicus | WLP653 | Horsey, Smoky, Spicy | Different from WY's "lambicus" |
Wyeast
Common Name | Species Name | Synonym (Strain) Name | Lab/Package | Flavor/Aroma | Source Note |
---|---|---|---|---|---|
Anomalus | Dekkera anomala | B. anomalus | Wyeast | bottled stout - Burton on Trent, England. Discontinued. | |
Bruxellensis | Dekkera bruxellensis | B. bruxellensis | Wyeast 5112 | "sweaty horse blanket" | Not the same as WL's Brux |
Claussennii | Dekkera anomala | B. claussenii | Wyeast 5151 | Notes of tropical fruit, pineapple and, to a lesser extent, peach and blueberry round out a classic Brett profile. Produces “horse blanket,” leathery, and smoky character, but at lower level than other Brett strains. Can be used as the primary strain for fermenting, but is often used after a primary fermentation with an S. cerevisiae strain, and in blends to produce sour beers. It is highly attenuative, given proper time to fully ferment out, and is known to create a pellicle during fermentation. | Private collection for Spring 2015. |
Lambicus | Dekkera bruxellensis | B. lambicus | Wyeast 5526 | Pie-cherry | Different from WL's "lambicus" |
Smaller Labs
Mfg | Taxonomy | Notes |
---|---|---|
BKYeast | Brett X1 | Suspected Brettanomyces Anomalus |
BKYeast | Brett C1 | Isolate from Cantillon Iris |
BKYeast | Brett C2 | Isolate from Cantillon Iris |
BKYeast | Brett C3 | Isolate from Cantillon Iris |
DCYeast | DCY01 | |
Saccharolicious | Brett I | Brettanomyces yeast from a Walloon Trappist brewery that gives an earthy aroma to the beer. Recommended for secondary fermentation after primary fermentation with Trappist O. |
Saccharolicious | Brett II | Fruity Brettanomyces yeast strain with an aroma that reminds of French cider. originates from Brasserie à Vapeur in Pipaix, Belgium, and was isolated from a bottle of Cochonne. |
Brett Blends (Brett only)
Manufacturer | Package | Notes |
---|---|---|
East Coast Yeast | ECY34 | Twelve (12) different isolates of Brettanomyces exhibiting high production of barnyard "funk" and esters. Dryness, ripe fruit, and acidity will be encountered over a period of months and over time (>1 yr), may display gueuze-like qualities in complexity. Contains various isolates from lambic-producers, B. bruxellensis, B. anomala, B. lambicus, and B. naardenensis. For those who want the most from Brett yeast, whether a 100% Brett fermentation is desired or adding to secondary aging projects. Suggested fermentation temperature: 60-74 F. Attenuation high. |
The Yeast Bay | Beersel | not overly funky but there is a sweaty note hanging behind lemon and citrus fruits, nice blend of subtle funk and citrus/fruit |
The Yeast Bay | Brussels | similar to Beersel but with more funk in aroma and less fruit, complex barnyard character |
The Yeast Bay | Lochristi | Smells of Iris C2, probably the same, subtle blend with some delicate fruit, strawberry |
The Yeast Bay | Amalgamation Brett Super Blend | 6 Brett blend to create a dry beer with a bright and complex fruit-forward flavor and aroma, accompanied by some funk |
Using Brett
Primary versus Secondary Fermentation
Brettanomyces can be pitched into a beer at many points in the beer's fermentation life cycle. If used as the primary fermenter, the beer that is produced is often fruit forward and not very funky. A large cell count will be needed (somewhere between an ale and lager pitching rate). See the 100% Brettanomyces Fermentation page for more information. If pitched into a beer that has already been fermented by Saccharomyces, a wider range of flavors including the funkier flavors can be produced (see the Brettanomyces Metabolism section above). A small cell count of Brettanomyces is plenty for creating these flavors, and normally a starter is not necessary. See the Mixed Fermentation and Funky Mixed Fermentations pages for more information on using Brett in secondary.
Starter Information
Special thanks to Nick Impellitteri from The Yeast Bay, and Shawn Bainbridge from Milk The Funk, for guidance on this section.
When pitching just Brettanomyces from a commercial pure or blended culture and no other microbes, it is recommended to make a starter for the culture. If the Brettanomyces is being pitched into secondary, no starter is necessary unless the brewer suspects that the Brettanomyces has lost a lot of viability due to age, heat exposure, etc.
There are two concepts unique to Brettanomyces compared to Saccharomyces when considering doing a starter. First, Brettanomyces performs best in a "semi-aerobic" environment. This means that the oxygen levels are low, but also not non-existent. An initial blast of oxygen into the wort, and foil left over the top to allow the air to slowly diffuse into the starter should be enough oxygen for the starter. With too much oxygen introduction, Brettanomyces can produce a lot of acetic acid (this is species dependent). Since Brett does not flocculate very well, and cold crashing a Brett starter can lead to difficulties, limiting the acetic acid production during the starter fermentation by refraining from too much oxygen exposure is advised [30].
The second aspect of Brettanomyces cell growth is that it typically takes about 7-8 days to reach it's maximum growth [31]. Thus, each step of a starter for Brett should be 7-8 days.
A Brett starter strength and size can be accurately calculated using an online yeast calculator such as Mr. Malty or YeastCalc using the 'hybrid' yeast type setting. This will calculate a pitching rate somewhere between ale and lager pitching rates, which should be adequate for 100% Brettanomyces fermentations. Maintaining a temperature of 70°-80°F/20°-26°C should be adequate for most strains. After the 7-8 days of growth, the entire starter should be pitched into the fermenter Brettanomyces is known for not flocculating well, even if cold crashed. Cold crashing will also slow the metabolism of Brett. Therefore cold crashing is generally not advisable.
It is worth noting that a "Malt Yeast Peptone Glucose" growth substrate has been shown to be a better substrate for growing an initial pitch of Brettanomyces. Specifically, when grown in wort, Brettanomyces will go through a 24 hour lag phase, a growth phase, another lag phase, and a second growth phase (all within 7-8 days). When grown in MYPG substrate, there is only a single growth phase and no lag phase, which has been reported by Yakobson to produce a larger cell count in the same amount of time [32]. Cells grown in MYPG also are better adapted to grow in wort [33]. Practical instructions for making this substrate can be found on Jason Rodriguez's blog, "Brew Science - Homebrew Blog".
Example of a Homemade Orbital Shaker
Mark Trent's shaker platform (obtained from a used equipment outlet in Gilroy, CA called "Outback Equipment" ) used to create a semi-aerobic environment for Brettanomyces. Mark built an insulated box for it, and added temperature control. He can propagate up to 7 liters. This is running at 80 RPM as described in The Brettanomyces project [34][35].
Storing Brett
Long term storage should be frozen with glycerol, rather than agar plates or slants [36]. Chad Yakobson noted that after storing Brett in a refrigerated environment (agar plates or slants?), after 6 months the Brett would die. If Brett is stored cold, it will be very sluggish and slow to start fermentation. Non-pure cultures (such as Brett in beer) should be stored refrigerated. Making a starter is highly recommended if the Brett culture has been stored cold [37].
Tips From Brewers
The Yeast Bay Lochristi Brett Blend
- Both Ed Coffey and Amos Browne have noted that this blend ages particularly well.
- To make a starter for the Lochristi blend, run it semi-aerobic for 4-6 days in the 70's and then let it settle at room temp and decant what you can if the starter is large [38].
See Also
Additional Articles on MTF Wiki
- 100% Brettanomyces Fermentation
- Crooked Stave Artisan Beer Project
- Scientific Publications
- Secondary metabolites
- Mixed Cultures
- Mixed Fermentation
- Funky Mixed Fermentations
External Resources
- Family tree of Brettanomyces, by Eureka Brewing Blog.
- Insight into the Brettanomyces Mitochondrial Genome, by Eureka Brewing Blog.
- National Collection of Yeast Cultures in the UK - Database on what compounds different species/strains can ferment.
- The Brettanomyces Project - Chad Yakobon's Brett research.
- The Mad Fermentationist - Commercial Brettanomyces, Lactobacillus, and Pediococcus Descriptions
References
- ↑ Wikipedia. Brettanomyces. Retrieved 2/24/2015.
- ↑ 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.
- ↑ [http://en.wikipedia.org/wiki/Secondary_metabolite Wikipedia. Secondary Metabolite. Retrieved 6/2/2015.
- ↑ Yakobson, Chad. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Production of Secondary Metabolites. 2011.
- ↑ Haz-Map, Ethyl Lactate odor threshold.
- ↑ Burdock, George A. Fenaroli's Handbook of Flavor Ingredients, Fifth Edition. CRC Press. 2005. pg 1521.
- ↑ YMDB. Phenethyl acetate.
- ↑ Aroxa. Ethyl butyrate. Retrieved 1/18/2015.
- ↑ Flavoractiv. Ethyl butyrate. Retrieved 1/18/2015.
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 Yakobson, Chad. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Pure Culture Fermentation Discussion. 2011.
- ↑ Wikipedia. Ethyl Decanoate. Retrieved 1/18/2015.
- ↑ Spedding, Gary. Flavor notes for Michigan Craft Guild Conference. 2014.
- ↑ Encyclopedia of Food Microbiology. Batt, Carl A. Academic Press. Sep 28, 1999. Pg 320.
- ↑ Aroxa. ethyl hexanoate. Retrieved 1/18/2015.
- ↑ Chemspider. Ethylhexanoat. Retrieved 1/18/2015.
- ↑ Ethyl Octanoate. The Good Scents Company. Retrieved 5/28/2015.
- ↑ Chop & Brew - Episode 37: Influence of Mashing on Sour Beer Production by Michael Tonsmeire. NHC 2014 Presentation. At 26 minutes. Retrieved 5/28/2015.
- ↑ Esters Detection Tresholds & Molecular Structures. Leffingwell & Associates. Retrieved 5/28/2015.
- ↑ Aroxa. Isaoamyl acetate. Retrieved 1/18/2015.
- ↑ Spaepen and Verachtert, 1982. Esterase Activity in the Genus Brettanomyces
- ↑ Doss, Greg. Brettanomyces: Flavors and performance of single and multiple strain fermentations with respect to time. Presentation at 2008 NHC. pg 12.
- ↑ Yakobson, Chad. Brettanomyces in Brewing the horse the goat and the barnyard. 1/14/2011
- ↑ Botha, Janita J. Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African wines. March 2010. Pg 2, 13, 17, 18
- ↑ Oelofse, Adriaan. Investigating the role of Brettanomyces and Dekkera during winemaking. December 2008.
- ↑ FlavorActV. Caprylic Acid. Retrieved 2/10/2015.
- ↑ "Decanoic acid". Wikipedia.
- ↑ Humbard, Matt. Milk The Funk Discussion. 3/10/2015.
- ↑ Ryan Steagall's conversation with White Labs on Facebook. April 10, 2015.
- ↑ White Labs 644 Explanation. 04/09/2015. Retrieved 5/2/2015.
- ↑ Brettanomyces bruxellensis: effect of oxygen on growth and acetic acid production. Aguilar Uscanga, Délia1, and Strehaiano. 2003.
- ↑ Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Results. Retrieved 2/17/2015
- ↑ Yakobson, Chad. The Brettanomyces Project. MYPG Compared to Wort as a Growth Substrate. Retrieved 2/18/2015.
- ↑ Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Discussion. Paragraph 5. Retrieved 2/18/2015.
- ↑ [http://www.brettanomycesproject.com/dissertation/propagation-and-batch-culture-growth/propagation-methods/ Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Methods. Retrieved 2/18/2015.
- ↑ Discussion with Mark Trent on Milk The Funk. 4/2/2015.
- ↑ Conversation with Matt Humbard, Ritchie Preiss, and Jeff Melo on MTF. 6/4/2015.
- ↑ Yakobson, Chad. Presentation at 2012 Music City Brew Off. At 43:00.
- ↑ Nick Impellitteri of The Yeast Bay on a MTF thread. Feb 17, 2015.