Difference between revisions of "Brettanomyces"

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This presents a sort of "catch 22" when growing ''Brett'' in a starter.  The brewer must weigh the pros and cons of how much aeration to give.  If the ''Brett'' is going to be used in a [[100% Brettanomyces Fermentation]], for example, then a stir plate may be the best choice.  If the ''Brett'' is instead being pitched in secondary with the intention of long aging, then having a high cell count isn't as necessary and the risk of adding more acetic acid/ethyl acetate to an aging beer is greater.  If a lot of acetic acid is produced during the starter, it is advised to cold crash and decant the starter.  ''Brett'' can have a difficult time flocculating and settling out, even when cold crashed.  The brewer may need to allow a few days for the cells to fully sediment <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1099473923414154/?comment_id=1099522943409252&offset=0&total_comments=25&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Richard Preiss of Escarpment Yeast Labs on MTF.  6/26/2015.]</ref>.  Additionally, 'Brett' that is cold crashed may be slower to begin fermentation.  If the brewer believes that the amount of acetic acid produced was insignificant, then cold crashing can be skipped and the entire starter can be pitched.         
 
This presents a sort of "catch 22" when growing ''Brett'' in a starter.  The brewer must weigh the pros and cons of how much aeration to give.  If the ''Brett'' is going to be used in a [[100% Brettanomyces Fermentation]], for example, then a stir plate may be the best choice.  If the ''Brett'' is instead being pitched in secondary with the intention of long aging, then having a high cell count isn't as necessary and the risk of adding more acetic acid/ethyl acetate to an aging beer is greater.  If a lot of acetic acid is produced during the starter, it is advised to cold crash and decant the starter.  ''Brett'' can have a difficult time flocculating and settling out, even when cold crashed.  The brewer may need to allow a few days for the cells to fully sediment <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1099473923414154/?comment_id=1099522943409252&offset=0&total_comments=25&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Richard Preiss of Escarpment Yeast Labs on MTF.  6/26/2015.]</ref>.  Additionally, 'Brett' that is cold crashed may be slower to begin fermentation.  If the brewer believes that the amount of acetic acid produced was insignificant, then cold crashing can be skipped and the entire starter can be pitched.         
  
−
A ''Brett'' starter strength and size can be accurately calculated using an online yeast calculator such as [http://www.mrmalty.com/calc/calc.html Mr. Malty] or [http://yeastcalculator.com/ 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 Fermentation]].  Maintaining a temperature of 70°-80°F/20°-26°C should be adequate for most strains.  ''Brettanomyces'' cell growth typically takes about 7-8 days to reach it's maximum growth <ref>[http://www.brettanomycesproject.com/dissertation/propagation-and-batch-culture-growth/propagation-results/ Yakobson, Chad.  The Brettanomyces Project.  Propagation and Batch Culture Results.  Retrieved 2/17/2015]</ref>.  Thus, each step of a starter for Brett should be 7-8 days.  
+
<span style="text-decoration: line-through;">A ''Brett'' starter strength and size can be accurately calculated using an online yeast calculator such as [http://www.mrmalty.com/calc/calc.html Mr. Malty] or [http://yeastcalculator.com/ 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 Fermentation]].</span> Maintaining a temperature of 70°-80°F/20°-26°C should be adequate for most strains.  ''Brettanomyces'' cell growth typically takes about 7-8 days to reach it's maximum growth <ref>[http://www.brettanomycesproject.com/dissertation/propagation-and-batch-culture-growth/propagation-results/ Yakobson, Chad.  The Brettanomyces Project.  Propagation and Batch Culture Results.  Retrieved 2/17/2015]</ref>.  Thus, each step of a starter for Brett should be 7-8 days.  
  
 
For breweries with laboratory capabilities, "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 <ref>[http://www.brettanomycesproject.com/2009/08/mypg-vs-wort-as-the-growth-substrate/ Yakobson, Chad.  The Brettanomyces Project.  MYPG Compared to Wort as a Growth Substrate.  Retrieved 2/18/2015.]</ref>.  Cells grown in MYPG also are better adapted to grow in wort <ref>[http://www.brettanomycesproject.com/dissertation/propagation-and-batch-culture-growth/propagation-discussion/ Yakobson, Chad.  The Brettanomyces Project.  Propagation and Batch Culture Discussion.  Paragraph 5.  Retrieved 2/18/2015.]</ref>.  Practical instructions for making this substrate can be found on Jason Rodriguez's blog, "[http://sciencebrewer.com/2011/04/29/wild-yeast-project-mypg-culture-media/ Brew Science - Homebrew Blog]".
 
For breweries with laboratory capabilities, "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 <ref>[http://www.brettanomycesproject.com/2009/08/mypg-vs-wort-as-the-growth-substrate/ Yakobson, Chad.  The Brettanomyces Project.  MYPG Compared to Wort as a Growth Substrate.  Retrieved 2/18/2015.]</ref>.  Cells grown in MYPG also are better adapted to grow in wort <ref>[http://www.brettanomycesproject.com/dissertation/propagation-and-batch-culture-growth/propagation-discussion/ Yakobson, Chad.  The Brettanomyces Project.  Propagation and Batch Culture Discussion.  Paragraph 5.  Retrieved 2/18/2015.]</ref>.  Practical instructions for making this substrate can be found on Jason Rodriguez's blog, "[http://sciencebrewer.com/2011/04/29/wild-yeast-project-mypg-culture-media/ Brew Science - Homebrew Blog]".

Revision as of 20:34, 26 July 2015

Brettanomyces
Brett Aroma Wheel by Dr. Linda Bisson and Lucy Joseph at UC Davis

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.

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 [6]
Phenethyl acetate (sweet, honey, rose flower like) Acetyl-CoA, 2-phenylethanol 3-5ppm (odor), 5-10ppm (flavor) [7] [8]
Ethyl butyrate (pineapple, mango, tropical fruit [9]) Butyric Acid 0.4ppm (flavor) [10] Low levels of production by some species of Brettanomyces; production decreases with higher acidity [11]
Ethyl Decanoate (brandy, fruity, oily, grape) Capric Acid (Decanoic acid) and ethanol [12] Also known as Ethyl caprate, Ethyl caprinate, and Capric acid ethyl ester [13]
Ethyl caproate (sweet, fruity, pineapple, banana, apple or aniseed) Caproic acid [14] 0.2ppm (flavor) [15] Also known as Ethyl hexanoate, Ethyl butyl acetate, and butylacetate [16]
Ethyl caprylate (Sweet, waxy, fruity and pineapple with creamy, fatty, mushroom and cognac notes [17]) Caprylic acid (contained in buckwheat; produced by yeast autolysis) and ethanol [18] 15ppb (flavor) [19] Also known as ethyl octanoate
Isoamyl Acetate (banana) Acetic Acid, Isoamyl alcohol 1.1ppm (flavor) [20] Produced by certain Saccharomyces strains but concentrations are generally reduced by Brettanomyces. [21]

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-Coumaric 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
[22] [23]

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) [11]. 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 [11].
Isovaleric Acid (Feety, parmesian) [24][25] Leucine Commonly described as a "spoilage" acid produced by Brettanomyces in wine, but also appears in beer.
Caproic acid (Fatty, cheesy, waxy, barnyardy) [11] Fatty acid.
Enanthic acid (Rancid odor) [11] Fatty acid.
Caprylic acid (Rancid-like smell and taste [11] Fatty acid. Also found in milk. Gives a waxy/oily mouthfeel. Flavor is more intense at low pH levels. Also called octanoic acid.[26]
Pelargonic acid (Rancid odor) [11] Fatty acid.
Capric acid (Barnyard animal odor/taste) [11] Fatty acid. Also found in milk, coconut oil, and seed oils [27].
Undecylic acid [11] Fatty acid.
Lauric acid (faint odor of bay oil or soap) [11] 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 [28].

Commercial Cultures

Pure cultures. In cooperation with Funk Factory.

Bootleg Biology

Unknown Unknown Unknown BB0034A – Funk Weapon Series: #1 This rare, and commercially unavailable yeast isolate, produces pungent horse blanket and fresh leather aromas. Perfect for breaking out the funk in farmhouse-style beers.

This is the first release in the Dusty Bottoms Collection’s ongoing Funk Weapon Series of unique, rare Brettanomyces and Brett-like wild yeast cultures. || West Flanders, Belgium brewery specializing in funky, sour, mixed-fermentation beers.

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 [29] [30].
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

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., or prefers higher cell count pitches.

There are generally two approaches to handling Brett starters. The first is to use a stir plate set to a low RPM for 7-8 days, cold crash for a few days, and then decant the beer before pitching the sedimented yeast. The second approach is to use an orbital shaker set to 80 RPM to create a semi-aerobic environment (this means that the oxygen levels are low, but also not non-existent) for 7-8 days as described in The Brettanomyces project [31], cold crashing can be skipped, and the entire starter is pitched into the wort. An alternative to the second approach is to give the starter an initial dosage of pure O2, and then to cover it with foil so that oxygen can slowly diffuse into the starter [32].

Oxygen levels are an important factor to consider when deciding which method to use for a Brett starter. Brettanomyces creates acetic acid in the presence of oxygen, potentially leading to higher levels of ethyl acetate, which is considered an off flavor in higher amounts. As the amount of oxygen increases, cell growth increases, but so does acetic acid production. The amount of acetic acid produced is species/strain dependent, so some strains may benefit from more aeration without having the negative effect of creating too much acetic acid. Other strains may need a less aerobic starter (semi-aerobic) in order to produce the highest cell count with minimal acetic acid [33][34][35].

This presents a sort of "catch 22" when growing Brett in a starter. The brewer must weigh the pros and cons of how much aeration to give. If the Brett is going to be used in a 100% Brettanomyces Fermentation, for example, then a stir plate may be the best choice. If the Brett is instead being pitched in secondary with the intention of long aging, then having a high cell count isn't as necessary and the risk of adding more acetic acid/ethyl acetate to an aging beer is greater. If a lot of acetic acid is produced during the starter, it is advised to cold crash and decant the starter. Brett can have a difficult time flocculating and settling out, even when cold crashed. The brewer may need to allow a few days for the cells to fully sediment [36]. Additionally, 'Brett' that is cold crashed may be slower to begin fermentation. If the brewer believes that the amount of acetic acid produced was insignificant, then cold crashing can be skipped and the entire starter can be pitched.

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 Fermentation. Maintaining a temperature of 70°-80°F/20°-26°C should be adequate for most strains. Brettanomyces cell growth typically takes about 7-8 days to reach it's maximum growth [37]. Thus, each step of a starter for Brett should be 7-8 days.

For breweries with laboratory capabilities, "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 [38]. Cells grown in MYPG also are better adapted to grow in wort [39]. 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 [31][40].

Storing Brett

Long term storage should be frozen with glycerol, rather than agar plates or slants [41]. 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 beer bottle dregs with Brett in it) should be stored refrigerated. Making a starter is highly recommended if the Brett culture has been stored cold [42].

Tips From Brewers

The Yeast Bay Lochristi Brett Blend

  • 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 [43].

See Also

Additional Articles on MTF Wiki

External Resources

References

  1. ↑ Wikipedia. Brettanomyces. Retrieved 2/24/2015.
  2. ↑ 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.
  3. ↑ [http://en.wikipedia.org/wiki/Secondary_metabolite Wikipedia. Secondary Metabolite. Retrieved 6/2/2015.
  4. ↑ Yakobson, Chad. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Production of Secondary Metabolites. 2011.
  5. ↑ Haz-Map, Ethyl Lactate odor threshold.
  6. ↑ Yakobson, Chad. The Brettanomyces Project. Impact of the Initial Concentration of Lactic Acid on Pure Culture Fermentation. Retrieved 6/16/2015.
  7. ↑ Burdock, George A. Fenaroli's Handbook of Flavor Ingredients, Fifth Edition. CRC Press. 2005. pg 1521.
  8. ↑ YMDB. Phenethyl acetate.
  9. ↑ Ethyl Butyrate Beer Flavour Standard. FlavorActIV. Retrieved 6/20/2015.
  10. ↑ Flavoractiv. Ethyl butyrate. Retrieved 1/18/2015.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 Yakobson, Chad. Pure Culture Fermentation Characteristics of Brettanomyces Yeast Species and Their Use in the Brewing Industry. Pure Culture Fermentation Discussion. 2011.
  12. ↑ Wikipedia. Ethyl Decanoate. Retrieved 1/18/2015.
  13. ↑ Spedding, Gary. Flavor notes for Michigan Craft Guild Conference. 2014.
  14. ↑ Encyclopedia of Food Microbiology. Batt, Carl A. Academic Press. Sep 28, 1999. Pg 320.
  15. ↑ Aroxa. ethyl hexanoate. Retrieved 1/18/2015.
  16. ↑ Chemspider. Ethylhexanoat. Retrieved 1/18/2015.
  17. ↑ Ethyl Octanoate. The Good Scents Company. Retrieved 5/28/2015.
  18. ↑ Chop & Brew - Episode 37: Influence of Mashing on Sour Beer Production by Michael Tonsmeire. NHC 2014 Presentation. At 26 minutes. Retrieved 5/28/2015.
  19. ↑ Esters Detection Tresholds & Molecular Structures. Leffingwell & Associates. Retrieved 5/28/2015.
  20. ↑ Aroxa. Isaoamyl acetate. Retrieved 1/18/2015.
  21. ↑ Spaepen and Verachtert, 1982. Esterase Activity in the Genus Brettanomyces
  22. ↑ Doss, Greg. Brettanomyces: Flavors and performance of single and multiple strain fermentations with respect to time. Presentation at 2008 NHC. pg 12.
  23. ↑ Yakobson, Chad. Brettanomyces in Brewing the horse the goat and the barnyard. 1/14/2011
  24. ↑ Botha, Janita J. Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African wines. March 2010. Pg 2, 13, 17, 18
  25. ↑ Oelofse, Adriaan. Investigating the role of Brettanomyces and Dekkera during winemaking. December 2008.
  26. ↑ FlavorActV. Caprylic Acid. Retrieved 2/10/2015.
  27. ↑ "Decanoic acid". Wikipedia.
  28. ↑ Humbard, Matt. Milk The Funk Discussion. 3/10/2015.
  29. ↑ Ryan Steagall's conversation with White Labs on Facebook. April 10, 2015.
  30. ↑ White Labs 644 Explanation. 04/09/2015. Retrieved 5/2/2015.
  31. ↑ 31.0 31.1 Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Methods. Retrieved 2/18/2015.
  32. ↑ Conversation with Nick Impellitteri on MTF in regards to semi-aerobic starters. 2/16/2015.
  33. ↑ Brettanomyces bruxellensis: effect of oxygen on growth and acetic acid production. Aguilar Uscanga, Délia1, and Strehaiano. 2003.
  34. ↑ Role of oxygen on acetic acid production by Brettanomyces/Dekkera in winemaking. Maurizio Ciani and Luisa Ferraro. April 1999.
  35. ↑ Acetic acid production by Dekkera/Brettanomyces yeasts. S.N. Feer. April 2002.
  36. ↑ Conversation with Richard Preiss of Escarpment Yeast Labs on MTF. 6/26/2015.
  37. ↑ Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Results. Retrieved 2/17/2015
  38. ↑ Yakobson, Chad. The Brettanomyces Project. MYPG Compared to Wort as a Growth Substrate. Retrieved 2/18/2015.
  39. ↑ Yakobson, Chad. The Brettanomyces Project. Propagation and Batch Culture Discussion. Paragraph 5. Retrieved 2/18/2015.
  40. ↑ Discussion with Mark Trent on Milk The Funk. 4/2/2015.
  41. ↑ Conversation with Matt Humbard, Ritchie Preiss, and Jeff Melo on MTF. 6/4/2015.
  42. ↑ Yakobson, Chad. Presentation at 2012 Music City Brew Off. At 43:00.
  43. ↑ Nick Impellitteri of The Yeast Bay on a MTF thread. Feb 17, 2015.
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