Brettanomyces is a type of yeast giving very outspoken aromas and flavor. Earthy, floral, spicy are the most common used descriptions. Different than the regular Sacccaromyces it is able to eat about every single sugar, resulting over time in very dry beers. Depending on the use, “Brett beers” can be sour.
A few typical bacteria, usually not far away when talking Brett are Lactobacillus, pediococcus and Acetobacter. The first producing lactid acid, as seen in your yoghurt, the second doing something simular under different circumstances, with a more tart result. Acetobacter is the least known of the three, it is a key-component in vinegar and can easily ruin your beer. However, they are must in Flemish red ales (www.wildegist.nl/about/).
Peter Perrecone heeft een presentatie gehouden voor de society of barley engineers (PDF). Vinnie Cilurzo heeft hier een presentatie over gegeven genaamd: Brewing Sour Beers at Home Using Traditional & Alternative Methods (door Brian Schmaltz, op Linkedin gezet) en Gail Williams heeft een presentatie gegeven met de titel Never too soon to go sour - sour beer homebrewing ideas.
Brettanomyces is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often called "Brett". The genus name Dekkera is used interchangeably with Brettanomyces, as it describes the spore forming form of the yeasts (http://societyofbarleyengineers.org/wp-content/uploads/2013/08/Peter_Perrecone_The_World_of_Brettanomyces.pdf).
Brett is a component in a number of traditional styles -- Lambic, Saison, Flanders Red & Brown. This was initially due to the spontaneous fermentation methods used (pre modern biology), later to preserve and maintain the style. It's become more trendy in the last 5 years or so to brew traditionally "clean" or pure Saccharomyces cerevisiae styles with some (or all) Brett.
#2atpca, Sep 24, 2014 (www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
Brettanomyces aka Botanical-myacies is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often colloquially referred to as "Brett". The genus name Dekkera is used interchangeably with Brettanomyces, as it describes the teleomorph or spore forming form of the yeast. The cellular morphology of the yeast can vary from ovoid to long "sausage" shaped cells. The yeast is acidogenic, and when grown on glucose rich media under aerobic conditions, produces large amounts of acetic acid. Brettanomyces is important to both the brewing and wine industries due to the sensory compounds it produces.
In the wild, Brettanomyces lives on the skins of fruit. The strain Brettanomyces claussenii was first classified at the Carlsberg brewery in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales. The term Brettanomyces comes from the Greek for "British fungus."
...
In most beer styles Brettanomyces is viewed as a contaminant and the characteristics it imparts are considered unwelcome "off-flavours." However, in many styles, particularly certain traditional Belgian ales, it is appreciated and encouraged. Lambic and gueuze owe their unique flavour profiles to Brettanomyces, as do wild yeast saison or farmhouse styles; and it is also found in Oud Bruin and Flanders red ale.
Several American craft breweries use Brettanomyces in their beers. This use began with a renewed interest in Belgian style ales and later formed new styles altogether (Brewers Association, 2007 Great American Beer Festival Style Guidelines, section 13a, 16). Some breweries use 100% Brettanomyces for the fermentation of some of their beers, and omit Saccharomyces from the recipe. It is common for American brewers that use Brettanomyces to also include lactic acid producing bacteria such as Lactobacillus, and Pediococcus in order to provide sourness to the beer. While Brett is sometimes pitched into the fermenter, aging in wood barrels previously inoculated with Brettanomyces is another method used to impart the complexity and sourness contributed by these strains of yeast.(https://en.wikipedia.org/wiki/Brettanomyces)
Zie hier en hier een strainoverzicht, en hier een myco-overzicht.
In the wild, Brettanomyces lives on the skins of fruit. The strain Brettanomyces claussenii was discovered at the Carlsberg brewery in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales. The term Brettanomyces comes from the Greek word "British fungus." (http://societyofbarleyengineers.org/wp-content/uploads/2013/08/Peter_Perrecone_The_World_of_Brettanomyces.pdf)
Tot nu toe werd het opgerekte domein van de spontane vergisting vooral bevolkt door een tikje avant-gardistische brouwers. Dat levert vaak bovengemiddeld uitgesproken smaken op en dat ook nog in een stijl die bekend staat als zuur bier. De Brettanomyces zetten suikers om in alcohol, zoals de gebruikelijke gistcellen dat ook doen, maar daarbij gaan tamelijk agressief vergistend te keer. Er blijft dus veel minder suiker over, met lekker droog bier als gevolg. Maar de Brettanomyces maken het bier niet alleen minder zoet, ze zorgen ook voor een zurige smaak. Die kan zo sterk zijn dat woorden als “paardendeken” nog wel eens willen vallen als een zuur bier beschreven wordt.
Dat betekent niet dat bier met “Brett” zich altijd kenmerkt door een allesverzengende zuurgraad. Voeg je wat Brettanomyces toe aan een bier dat op normale wijze vergist, dan kan ook een hele toegankelijke, lichtzurige fruitigheid opleveren. Het mooiste en bekendste voorbeeld van wat zo’n combinatie van Saccharomyces en Brettanomyces kan doen is misschien wel Orval. Aanvankelijk trekken de Saccharomyces de kar der vergisting voor dit unieke trappistenbier. Als het bier vervolgens de karakteristieke fles ingaat, wordt er zowel kandijsuiker als Brett aan toegevoegd (www.brouwerijhetij.nl/nieuw-bier-ij-brett-beetje-brett-niet-vies/).
Een voorbeeld van een bier met brett is de (middelste?) Orval, Oersoep Brettalicious Brett Saison - Foudre 1, Brettpeat , Wild Jo en IJ Brett. Als stijl kun je denken aan lambic, geuze, Vlaamse Bruine, Berliner Weisse, Göse en dergelijke.
However, while Brettanomyces strains are important to the production of lambics, Brett can and is used in the production of other beers, including classic styles and modern creations.
Brettanomyces is yeast; just not our good friend Saccharomyces cerevisiae (i.e., brewer’s yeast). Brettanomyces may also be called Dekkera. Dekkera is the name for the spore-forming version while Brettanomyces is used to refer to the non-spore forming version. There are many different species of Brett and in some cases, one species may be referred to by different names in different sources.
Beer or wine fermented in unlined wooden vessels are very likely to be tainted by Brettanomyces since Brett can survive for extended periods in the wood. There is evidence that at least some strains of Brett can slowly eat the sugars in the wood that other organisms can’t process.
In the very early part of the 20th Century, Brettanomyces was first isolated from wood-aged British strong stock ales by N. Claussen at the Carlsberg Brewery in Denmark. The name Brettanomyces means “British brewing industry fungus.” (The name Saccharomyces means “sugar fungus.”)
Het is ook een fenomeen bij wijn:
Brettanomyces is a common defect in wine, but controversy surrounds the subject. Jamie Goode sifts the available data and canvasses the views of world-famous winemakers to determine how widespread the problem is, and whether brett can ever be a good thing. (Originally published in Harpers Wine and Spirit Weekly, 18 April 2003, p 42-46)..... Volatile phenols and fatty acids are the key molecules responsible for the olfactory defects in wines affected by brettanomyces. According to Peter Godden, of the Australian Wine Research Institute, ‘The anecdotal dogma in this area is that 4-ethyl-phenol, isovaleric acid and 4-ethyl-guiacol are the key molecules, in order of sensory importance’. But he adds that he has seen variations in brett character in different bottles of the same wine. 4-ethyl-phenol is the most prominent molecule in bretty wines, giving aromas of stables, barnyards and sweaty saddles (apparently, but I must admit to never having smelled one). Its presence in wine is an almost certain indicator of a brett infection, and this is what most diagnostic labs test for to indicate the presence of brett. 4-ethyl-guiacol is a little more appealing, known for its smoky, spicy aromas. Isovaleric acid, a volatile fatty acid, is known for its rancid, horsey aroma, and as yet there is no analytical technique that picks it out: in gas chromatography/mass spectrometry (GCMS) another compound elutes at the same time, which masks it. Godden emphasizes that this is a complex area of study: ‘There is not much of a relationship between overall brett character and 4-ethyl-phenol levels, and there are synergistic effects between the three most important sensory compounds.’
As with other volatile odorants, people differ widely in their sensitivity to these molecules, and each individual shows a range of different thresholds (for example, the threshold for detecting an odorant differs from the threshold for recognition of the same odorant). Godden suggests that a useful sensory threshold to use for 4-ethyl-phenol is 420 micrograms/litre. At this concentration and beyond, a wine will typically be noticeably bretty. Below this concentration, the character of the wine may be changed but people won’t, on average, recognize that this is due to 4-ethyl-phenol. Because the threshold for 4-ethyl-phenol drops when 4-ethyl guiacol is also present -- and in brett-infected wine they always occur together in a ratio of about 10:1 -- this threshold is calculated for a 10:1 mixture of 4-ethyl-phenol and 4-ethyl-guiacol..... The conclusion seems to be that brettanomyces is widespread, and virtually every barrel of red wine has the potential to go bretty. Create the right environment for it, and you’ll have a brett infection. Thus the key objective for winemakers isn’t to create a sterile winery, which will never happen, but to make sure that their barrels aren’t a receptive environment for brett to grow in.... Randall Grahm has an novel suggestion, though: ‘It would be very interesting if we could isolate a strain of brett that worked in wine, depleting nutrients but producing very low levels of 4-ethyl phenol. In this way, one could inoculate one’s wine with brett, much the same way as one inoculates one’s wine with malolactic bacteria, thus depleting nutrients and rendering the wine safe from further microbial degradation.’ Now there’s a project for the microbiologists (www.wineanorak.com/brettanomyces.htm).
Brettanomyces, the industry’s most famous and controversial characteristic. But this had evidently not bothered the judges at the 2015 Decanter World Wine Awards who had given the wine a gold medal and a regional trophy (www.meininger.de/en/wine-business-international/great-brettanomyces-taste-test).
Nothing about Brettanomyces is straightforward. It even has another name – Dekkera – though one that’s rarely used by wine people. There are several different strains of Brett, each of which has a character of its own: some are more widely palatable than others. To complicate matters further, sensitivity to any of the strains varies from one human being to another. Even when two people perceive the same aromas, they may disagree widely over their acceptability. For one expert, a wine with detectable evidence of Brett is unpardonably faulty, while to another, the same wine will be greeted as complex and showing a sense of place. To untangle this web, it is worth looking at the facts over which there is no dispute.
Brettanomyces has the rare distinction of bringing together the worlds of beer and wine. A strain, Brettanomyces claussenii, was first identified at the Carlsberg brewery in Denmark by Niels Hjelte Claussen in 1903. Claussen was investigating a batch of sour English beer, which explains why the yeast came to be named after both him and the Greek for ‘British fungus’. Innovative brewers realised that despite its association with faulty ale, Brett might contribute to the production of interesting beer. In 1908, a letter was sent to the editor of a Chicago publication called The Western Brewer: and Journal of the Barley, Malt and Hop Trades saying that the writer had been ‘advised’ to used the yeast to ‘improve the flavour and taste’ of their ale. The answer was that Brettanomyces was not a ‘commercial article’, but a ‘group of micro-organisms’ that can be isolated from… old English ales and that it is the ferment which gives to these beers their… taste and flavour’. The enquirer was told that 125cc of a Brett culture per barrel would be ‘sufficient’.
Ever since, brewers have taken a passionate interest in the contribution an intentional addition of Brett can make to some styles of beer, and its undesirability in others. Today, Chad Yakobson MSc, founder of the Crooked Stave Artisan Beer Project in Denver, enjoys a cult following for his Brettanomyces Project experiments into using Brett in Belgian-style beer fermentation.
Brett’s relationship with wine is less clear. The first time the two were scientifically linked was in 1940, when a researcher called M.T.J. Custers performed a first systematic study on 17 strains of Brettanomyces yeast and found one in a wine. Three-quarters of a century later, while studies have been conducted by scientists such as Pascal Chatonnet of Laboratoire Excell in Bordeaux, winemakers still have less understanding of the subject than brewers. All too often, wines with the tell-tale Band-Aid or horsey character are thought to be displaying ‘terroir’. In a 2005 Guardian interview, Chatonnet admitted that when he began to make wine in the 1960s, he thought brett was a typical character of wines from Graves. Now, he is clear that the yeast is actually the enemy of terroir because wines infected with it will all taste the same.
When discussing the smell and taste of Brett, much depends both on the precise strains of the yeast, their concentration, combination, and the style and age of wine in which they appear. One of the main yeasts, 4-ethylphenol (usually referred to as 4-EP), is associated with ‘Band-Aid’ characters, while 4-ethylguaiacol (4-EG) is more pleasantly spicy and 4-ethylcatechol (4-EC]) is the barnyardy villain of the piece. Some fruity, well-structured wines will conceal their Brett component more effectively than lighter styles – until the fruit component fades over time, allowing the Band-Aid or stable characters to emerge. Pinot Noir seems to be particularly susceptible to the barnyard character while Shiraz and Nebbiolo sometimes take on the spicy notes.
While awareness and understanding of Brett has grown in tandem with greater technical understanding, there is also no doubt that there is also more Brett around. This is explained by the trend towards picking riper grapes, higher pH levels, residual sugar, more barrel ageing, a move away from filtration and – especially among ‘natural’ winemakers - a dramatic reduction in the use of SO2. While Brett infections have been found in vineyards and on grapes, barrels are often seen as the major culprit in the spread of the infection in a winery, especially as wine is racked from one cask to another.
As Randall Grahm of the Bonny Doon winery in California told me, “a certain portion of one's barrels can well be infected and others not. It's certainly then a reasonable strategy to sterile-filter the infected barrels and not filter the others. But it seems that it is still very tricky to have real certainty about whether your wine has Brett or not, as the testing methods seem to be not 100% reliable.”
In recent times, the argument over the acceptability and even desirability of small amounts of Brett has been enlivened by the growing trendiness of unsulphured, unfiltered, wild yeast-fermented ‘natural’ wines. Supporters of these styles are generally far more tolerant of characteristics such as volatile acidity and Brett. Alice Feiring, the New York-based author of Letting Grapes Do What Comes Naturally, has written about “earthy/savoury” Brett or “sheepiness” and says that if it does not “overwhelm the wine” it’s “terrific”.
Feiring is not alone. Plenty of well-respected palates have admired wines like Château de Beaucastel in Châteauneuf-du-Pape, Château Musar in Lebanon and Henschke’s Hill of Grace, all of which have historically – in at least some vintages – been associated with Brett (www.meininger.de/en/wine-business-international/great-brettanomyces-taste-test).
Maar even terug naar de geschiedenis, een stukje bierhistorie van Shut up about Barclay Perkins:
Ron (patto1ro) Pattinson's When was Brettanomyces discovered? blog entry has more on the history, pre-Claussen. #6jesskidden, Sep 24, 2014 (www.beeradvocate.com/...brettanomyces-history.214099/):
Trawling through the Journal of the Institute of brewing, I stumbled upon a little article about Brettanomyces by R. B. Gilliland. It was a revelation.
I'd accepted that it was Claussen, working at the Carlsberg laboratory, who first discovered Brettanomyces in 1903.It turns out that's not the whole truth... Claussen may have been the first to publish about Brattanomyces, but he wasn't the first to find it.
On the face of it, a brewery in St. Petersberg seems an even more unlikely place to come across Brettanomyces than in Denmark. But, if you think about it, there is some sense to it. In the late 19th century, about the only beer being imported into Russia was strong Stout. Stuff that would have been aged and gained its distinctive flavour from a Brettanomyces secondary conditioning. Someone trying to replicate such a beer might well go looking for the secondary conditioing yeast.
As for Guinness, well, they're exactly the sort of brewery you would expect to have discovered Brattanomyces. In the 1890's Guinness still vatted a decent quantity of beer. Foreign Extra Stout was mostly a vatted beer, but a proportion of aged beer was also blended into Extra Stout and Porter. While in Britain this sort of long maturation was only used for the strongest beers, it was a vital part of all Guinness's products.
Why didn't Seyffert or Tullo publish? In the former case, it was most likely a commercial decision. If you'd cracked the way of turning any old Lager into aged Stout, you'd quite likely want to keep it to yourself. There was potentially lots of money to be earned from that knowledge. Perhaps there was the same consideration at Guinness.
That also might explain why Claussen did publish. Secondary conditioning wasn't really part of Carlsberg's business (http://barclayperkins.blogspot.nl/2013/06/when-was-brettanomyces-discovererd.html, http://barclayperkins.blogspot.nl/2015/05/brettanomyces-hero-or-villain.html).
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The holder of the patent is N. Hjelte Claussen, the scientist who discovered brettanomyces at Carlsberg. I'm going to go ahead and hazard the observation that the Wiki site on his strain--brettanomyces claussenii--is wrong; it says he discovered the strain in 1904. Nice trick securing a patent on this technique a year before he discovered the actual strain.
I'll hazard a second observation as well: Claussen's scheme to pitch brett into lagers doesn't seem to have taken off. Sour lager (sauerlagern?)? Someone should give that a shot--there's a gold medal at the GABF waiting for the first brewery to perfect it (http://beervana.blogspot.nl/2012/01/ahead-of-his-time.html).
Er zijn 3 soorten van brett:
Here’s an overview of the properties of various types of Brettanomyces isolated from bottle-conditioned beers:
“Group 1. -21 strains fermented glucose, sucrose and maltose only. These strains agreed with the published descriptions of Brett. bruxellensis Kufferath et van Laer and were similar to authentic strains of this species. Brett. bruxellensis has been isolated from Iambic beer, from Cork porter, from French grape must and from Brazilian wine fermentations."
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 259.
Now the second group:
“Group 2. -11 strains fermented glucose and galactose only. These strains agreed with Peynaud & Domercq and were similar to an authentic strain of this species. Brett. schanderlii has been found in French and South African wine fermentations. It has not previously been reported as occurring in beer. "
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 259 - 260.
Interesting that this had previously only been found in wine, not beer.
This sounds like a weird one:
“Group 3. -12 strains fermented glucose, galactose, sucrose and lactose. This combination of fermentative abilities does not correspond with any established species. These strains are most like Brett. anomalus but differ from this species in that they ferment sucrose rapidly. A further study is being made of these strains and, if the differences are sufficient to establish the strains in this group as a separate species, this will be reported in a further communication. For the present these strains will be described as Brettanomyces sp. 1. It seems strange that so many strains unable to ferment maltose (Groups 2 and 3) should be found in beer, but Custers isolated Brett. anomalus, which also is unable to ferment maltose, from English beer. It was because of this peculiar circumstance that Custers gave this species the name "anomalus."”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.
You wouldn’t want that getting into your Milk Stout. Bottle bombs would be the inevitable result of the Brettanomyces chewing its way through the lactose (http://barclayperkins.blogspot.nl/2015/05/brettanomyces-hero-or-villain.html).
The compounds responsible for contributing certain sensory characters
to wine/beer are;
4-ethylphenol: Band-aids, barnyard, horse stable, antiseptic
4-ethylguaiacol: Bacon, spice, cloves, smoky
isovaleric acid: Sweaty saddle, cheese, rancidity
(http://societyofbarleyengineers.org/wp-content/uploads/2013/08/Peter_Perrecone_The_World_of_Brettanomyces.pdf)
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There has been lots of good posts concerning the ‘discovery’ of Brettanomyces in the late 1800s/early 1900s; N. Hjelte Claussen is often attributed as being the person who ‘discovered’ Brett since he published on this matter.
While yeast as a living organism was not discovered until 1857 by Louis Pasteur, brewers and bakers were aware of yeast as a needed ingredient. British brewers were cognizant that ‘something’ was adding tartness to their stock ales and porters in the 1700’s. Another recognition of ‘something’ was that the IPAs of the early 1800’s would come out being exceptionally dry (very low final gravities) when they were aged in wooden barrels for extended periods of time. They did not know the specifics of the science (i.e., Brett living in the wooden barrels conducting a secondary fermentation within the barrel) at that time but the effects were certainly recognized.
Cheers!
#9JackHorzempa, Sep 24, 2014 Last edited: Sep 24, 2014
(www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
If we're taking about modern craft brewing and the proliferation of Brett, Chad Yakobson of Crooked Stave deserves a mention for sure. Outside of making delicious beers with mixed cultures and especially 100% Brett beers, his research on Brett was pretty groundbreaking, and he's written plenty on the subject. Historically, someone already mentioned Orval, but Courage Russian Imperial Stout was another famous example of intentionally adding Brett for conditioning.
#10afrokaze, Sep 24, 2014 (www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
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Iemand heeft ook een website genaamd http://brettanomycesproject.com/ over zijn scriptie (MSc.) en dissertatie:
The Brettanomyces Master’s Project took 18 months to complete from start to finish. While it might not have taken so long had I not been working 40+ hours a week as a brewer for nine of those months, I still managed to complete the work finishing all the writing and submitting the dissertation on July 23rd, 2010 (http://brettanomycesproject.com/msc-project-archives/).
Pure culture fermentation characteristics of Brettanomyces yeast species and their use in the Brewing Industry (http://brettanomycesproject.com/dissertation/) This study was conducted to evaluate the pure culture fermentation performance of eight strains of Brettanomyces with the objective to find characteristic compounds produced during fermentation. Colony formation and growth was initially observed on media agars recommended for use in the brewing industry with strong growth observed on MYPG, WLN, and CuSO4 agar medias. Cell growth during semi aerobic batch culture showed 2-phase and 3-phase growth patterns with maximum cell counts reached after 168 to 192 hours of propagation. Pure culture fermentations were conducted with multiple pitching rates and variation was observed in the different strains abilities to achieve adequate attenuation after 35 days. Longer time was needed for most strains except B. bruxellensis (BSI-Drie), which achieved 82.16% apparent attenuation with a pitching rate of 6×106 cells/ml. When the strains were pitched at a rate of 12×106 cells/ml a correlation was observed between final pH and final apparent attenuation, with a lower final pH resulting in greater attenuation. Fermentations were further conducted with wort pre-acidified with lactic acid at concentration of 100, 500, 1,000 and 3,000 mg/l. Higher initial concentrations of lactic acid had a significant effect, increasing the level of attenuation observed in each strain, while generally decreasing the secondary metabolites produced. Compound analysis of the fermented beers showed ethyl acetate, ethyl caproate, and ethyl caprylate were the significant esters produced with no isoamyl acetate detected throughout the study. Of the esters produced, ethyl caproate and ethyl caprylate were produced at levels previously unseen in fermented beer (http://brettanomycesproject.com/dissertation/abstract/).
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A few typical bacteria, usually not far away when talking Brett are Lactobacillus, pediococcus and Acetobacter. The first producing lactid acid, as seen in your yoghurt, the second doing something simular under different circumstances, with a more tart result. Acetobacter is the least known of the three, it is a key-component in vinegar and can easily ruin your beer. However, they are must in Flemish red ales (www.wildegist.nl/about/).
Peter Perrecone heeft een presentatie gehouden voor de society of barley engineers (PDF). Vinnie Cilurzo heeft hier een presentatie over gegeven genaamd: Brewing Sour Beers at Home Using Traditional & Alternative Methods (door Brian Schmaltz, op Linkedin gezet) en Gail Williams heeft een presentatie gegeven met de titel Never too soon to go sour - sour beer homebrewing ideas.
Brett is a component in a number of traditional styles -- Lambic, Saison, Flanders Red & Brown. This was initially due to the spontaneous fermentation methods used (pre modern biology), later to preserve and maintain the style. It's become more trendy in the last 5 years or so to brew traditionally "clean" or pure Saccharomyces cerevisiae styles with some (or all) Brett.
#2atpca, Sep 24, 2014 (www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
Brettanomyces aka Botanical-myacies is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often colloquially referred to as "Brett". The genus name Dekkera is used interchangeably with Brettanomyces, as it describes the teleomorph or spore forming form of the yeast. The cellular morphology of the yeast can vary from ovoid to long "sausage" shaped cells. The yeast is acidogenic, and when grown on glucose rich media under aerobic conditions, produces large amounts of acetic acid. Brettanomyces is important to both the brewing and wine industries due to the sensory compounds it produces.
In the wild, Brettanomyces lives on the skins of fruit. The strain Brettanomyces claussenii was first classified at the Carlsberg brewery in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales. The term Brettanomyces comes from the Greek for "British fungus."
...
In most beer styles Brettanomyces is viewed as a contaminant and the characteristics it imparts are considered unwelcome "off-flavours." However, in many styles, particularly certain traditional Belgian ales, it is appreciated and encouraged. Lambic and gueuze owe their unique flavour profiles to Brettanomyces, as do wild yeast saison or farmhouse styles; and it is also found in Oud Bruin and Flanders red ale.
Several American craft breweries use Brettanomyces in their beers. This use began with a renewed interest in Belgian style ales and later formed new styles altogether (Brewers Association, 2007 Great American Beer Festival Style Guidelines, section 13a, 16). Some breweries use 100% Brettanomyces for the fermentation of some of their beers, and omit Saccharomyces from the recipe. It is common for American brewers that use Brettanomyces to also include lactic acid producing bacteria such as Lactobacillus, and Pediococcus in order to provide sourness to the beer. While Brett is sometimes pitched into the fermenter, aging in wood barrels previously inoculated with Brettanomyces is another method used to impart the complexity and sourness contributed by these strains of yeast.(https://en.wikipedia.org/wiki/Brettanomyces)
Zie hier en hier een strainoverzicht, en hier een myco-overzicht.
In the wild, Brettanomyces lives on the skins of fruit. The strain Brettanomyces claussenii was discovered at the Carlsberg brewery in 1904 by N. Hjelte Claussen, who was investigating it as a cause of spoilage in English ales. The term Brettanomyces comes from the Greek word "British fungus." (http://societyofbarleyengineers.org/wp-content/uploads/2013/08/Peter_Perrecone_The_World_of_Brettanomyces.pdf)
Tot nu toe werd het opgerekte domein van de spontane vergisting vooral bevolkt door een tikje avant-gardistische brouwers. Dat levert vaak bovengemiddeld uitgesproken smaken op en dat ook nog in een stijl die bekend staat als zuur bier. De Brettanomyces zetten suikers om in alcohol, zoals de gebruikelijke gistcellen dat ook doen, maar daarbij gaan tamelijk agressief vergistend te keer. Er blijft dus veel minder suiker over, met lekker droog bier als gevolg. Maar de Brettanomyces maken het bier niet alleen minder zoet, ze zorgen ook voor een zurige smaak. Die kan zo sterk zijn dat woorden als “paardendeken” nog wel eens willen vallen als een zuur bier beschreven wordt.
Dat betekent niet dat bier met “Brett” zich altijd kenmerkt door een allesverzengende zuurgraad. Voeg je wat Brettanomyces toe aan een bier dat op normale wijze vergist, dan kan ook een hele toegankelijke, lichtzurige fruitigheid opleveren. Het mooiste en bekendste voorbeeld van wat zo’n combinatie van Saccharomyces en Brettanomyces kan doen is misschien wel Orval. Aanvankelijk trekken de Saccharomyces de kar der vergisting voor dit unieke trappistenbier. Als het bier vervolgens de karakteristieke fles ingaat, wordt er zowel kandijsuiker als Brett aan toegevoegd (www.brouwerijhetij.nl/nieuw-bier-ij-brett-beetje-brett-niet-vies/).
Een voorbeeld van een bier met brett is de (middelste?) Orval, Oersoep Brettalicious Brett Saison - Foudre 1, Brettpeat , Wild Jo en IJ Brett. Als stijl kun je denken aan lambic, geuze, Vlaamse Bruine, Berliner Weisse, Göse en dergelijke.
However, while Brettanomyces strains are important to the production of lambics, Brett can and is used in the production of other beers, including classic styles and modern creations.
Brettanomyces is yeast; just not our good friend Saccharomyces cerevisiae (i.e., brewer’s yeast). Brettanomyces may also be called Dekkera. Dekkera is the name for the spore-forming version while Brettanomyces is used to refer to the non-spore forming version. There are many different species of Brett and in some cases, one species may be referred to by different names in different sources.
Beer or wine fermented in unlined wooden vessels are very likely to be tainted by Brettanomyces since Brett can survive for extended periods in the wood. There is evidence that at least some strains of Brett can slowly eat the sugars in the wood that other organisms can’t process.
In the very early part of the 20th Century, Brettanomyces was first isolated from wood-aged British strong stock ales by N. Claussen at the Carlsberg Brewery in Denmark. The name Brettanomyces means “British brewing industry fungus.” (The name Saccharomyces means “sugar fungus.”)
In the glory days of English porter (in the 18th and 19th Centuries), brewers built immense unlined wooden vats for aging their beers. Beers would age for up to a year before blending with younger beers for serving. These aged beers became somewhat sour and were called “stale,” a desirable characteristic. The stale porter could be worth two to three times as much as the young beer and aging porter became a capital-intensive business to satisfy the need for large volumes of stale porter needed for blending. Brewers held large dinner parties on the floor of new vats to commission these immense structures. Some of these vessels were as large as 20,000 barrels. The building of larger and larger vats continued through 1814 when a porter vat burst at the Horse Shoe Brewery in London. The ensuing deluge destroyed the brewery and the neighboring housing, resulting in the death of eight people.
It is very likely that Brettanomyces played a major role in the souring (staling) of historical porters though there were undoubtedly other organisms present as well.
Historically, Berliner weisse is said to have had Brettanomyces notes though the dominant souring agent is Lactobacillus. In the traditional process, the wort wasn’t boiled so other organisms may have had the opportunity to contaminate the wort.
In Belgium, the traditional farmhouse style saison was likely to have had a Brett character and even today the lambic family of beers depends on Brett (and many other organisms) for its character.
Likewise, since the Belgian Flanders red (as typified by Rodenbach Red) is still aged in unlined oak, it has contributions from Brett along with other organisms.
And of course, the world classic Trappist ale Orval — from Brasserie de l’Abbaye Notre-Dame d’Orval SA — incorporates Brett in its profile..... Brettanomyces is a souring agent and will produce both lactic and acetic acids. It will normally only produce a relatively low level of acetic acid and even then only under aerobic (with oxygen) conditions. Extended aging in wood allows a slow penetration of oxygen, resulting in some acetic acid in the beer. The Rodenbach Brewery has to periodically disassemble their large oak aging vats to scrape the inside of the wood staves to maintain the proper oxygen penetration rate in order to get their desired level of sourness.
Side effects of a Brettanomyces fermentation are often characterized by a sweaty horse, horse blanket, leathery, or even wet horse aroma that some people might generalize as barnyard-like aromas. Additional characteristics sometimes produced by Brett include spicy, smoky, medicinal, and even cheesy. In some strains there can be a somewhat unpleasant mousy (or mouse-urine like) aroma.
Brettanomyces-influenced fermentation will usually show a pellicle, a coarse off-white mat that floats on the surface. The pellicle tends to protect the beer from oxidation as well as protecting the beer from molds and Acetobacter (acetic acid bacteria). A pellicle can even form in a bottle if there is enough food left for the Brett to feed on.
Some strains of Brett will produce distinct cherry pie-like flavors and aromas. For example, the B. lambicus strain Wyeast sells is known for producing the cherry characteristics.
Brettanomyces is a super attenuating yeast — it is able to process sugars and dextrins that normal yeast can’t process. Over time, Brett will consume almost all the sugars and dextrins in a beer. Most beers with any traces of Brett will end up very dry as the yeast can survive for months or even years in the fermenter or bottle.
Brett is capable of producing CO2 and therefore can be used to bottle condition beers. However, the continued action of Brett almost always leads to increasing levels of carbonation over time. If a Brett-influenced beer is bottled too soon, you run the risk of making “bottle bombs.”
Brettanomyces produces three compounds with high sensory profiles: 4-ethyl phenol, 4-ethyl guaiacol and isovaleric acid. 4-ethyl phenol can be detected by most people at 200–600 parts per million. 4-ethyl phenol gets credit for “band-aid” and barnyard aromas and 4-ethyl guaiacol for the wet, burnt wood, spicy smells. Isovaleric acid and its esters can be downright fruity (it’s a component in commercially-prepared blueberry, pineapple and peach aroma enhancers), but can also contribute a rancid character.
Brettanomyces has nutritional requirements similar to brewer’s yeast, though some sources indicate that certain strains can’t tolerate alcohol levels above 13%. Brett doesn’t grow well at cool temperatures or at pH values lower than about 3.4. (Most beers have less alcohol and higher pH levels than this, however.)
Brett is a slow growing organism and grows best in a temperature range between 13–30 ºC (55–86 ºF). At the higher end of the growth range, Brett is likely to produce more unpleasant flavors and aromas whereas at the low end it seems the characteristic flavors and aromas are emphasized.
There are essentially two ways Brettanomyces can be used — as a secondary component of a mixed fermentation or as the dominant (or sole) microorganism in a fermentation. Using Brett along with other organisms — as in brewing lambics, Flanders red ales or Brett-tainted historical styles — is fairly straightforward compared with brewing Brett-dominated beers (including 100% Brettanomyces fermented beers) (http://byo.com/mead/item/262-brettanomyces).
Brettanomyces is a common defect in wine, but controversy surrounds the subject. Jamie Goode sifts the available data and canvasses the views of world-famous winemakers to determine how widespread the problem is, and whether brett can ever be a good thing. (Originally published in Harpers Wine and Spirit Weekly, 18 April 2003, p 42-46)..... Volatile phenols and fatty acids are the key molecules responsible for the olfactory defects in wines affected by brettanomyces. According to Peter Godden, of the Australian Wine Research Institute, ‘The anecdotal dogma in this area is that 4-ethyl-phenol, isovaleric acid and 4-ethyl-guiacol are the key molecules, in order of sensory importance’. But he adds that he has seen variations in brett character in different bottles of the same wine. 4-ethyl-phenol is the most prominent molecule in bretty wines, giving aromas of stables, barnyards and sweaty saddles (apparently, but I must admit to never having smelled one). Its presence in wine is an almost certain indicator of a brett infection, and this is what most diagnostic labs test for to indicate the presence of brett. 4-ethyl-guiacol is a little more appealing, known for its smoky, spicy aromas. Isovaleric acid, a volatile fatty acid, is known for its rancid, horsey aroma, and as yet there is no analytical technique that picks it out: in gas chromatography/mass spectrometry (GCMS) another compound elutes at the same time, which masks it. Godden emphasizes that this is a complex area of study: ‘There is not much of a relationship between overall brett character and 4-ethyl-phenol levels, and there are synergistic effects between the three most important sensory compounds.’
As with other volatile odorants, people differ widely in their sensitivity to these molecules, and each individual shows a range of different thresholds (for example, the threshold for detecting an odorant differs from the threshold for recognition of the same odorant). Godden suggests that a useful sensory threshold to use for 4-ethyl-phenol is 420 micrograms/litre. At this concentration and beyond, a wine will typically be noticeably bretty. Below this concentration, the character of the wine may be changed but people won’t, on average, recognize that this is due to 4-ethyl-phenol. Because the threshold for 4-ethyl-phenol drops when 4-ethyl guiacol is also present -- and in brett-infected wine they always occur together in a ratio of about 10:1 -- this threshold is calculated for a 10:1 mixture of 4-ethyl-phenol and 4-ethyl-guiacol..... The conclusion seems to be that brettanomyces is widespread, and virtually every barrel of red wine has the potential to go bretty. Create the right environment for it, and you’ll have a brett infection. Thus the key objective for winemakers isn’t to create a sterile winery, which will never happen, but to make sure that their barrels aren’t a receptive environment for brett to grow in.... Randall Grahm has an novel suggestion, though: ‘It would be very interesting if we could isolate a strain of brett that worked in wine, depleting nutrients but producing very low levels of 4-ethyl phenol. In this way, one could inoculate one’s wine with brett, much the same way as one inoculates one’s wine with malolactic bacteria, thus depleting nutrients and rendering the wine safe from further microbial degradation.’ Now there’s a project for the microbiologists (www.wineanorak.com/brettanomyces.htm).
Brettanomyces, the industry’s most famous and controversial characteristic. But this had evidently not bothered the judges at the 2015 Decanter World Wine Awards who had given the wine a gold medal and a regional trophy (www.meininger.de/en/wine-business-international/great-brettanomyces-taste-test).
Nothing about Brettanomyces is straightforward. It even has another name – Dekkera – though one that’s rarely used by wine people. There are several different strains of Brett, each of which has a character of its own: some are more widely palatable than others. To complicate matters further, sensitivity to any of the strains varies from one human being to another. Even when two people perceive the same aromas, they may disagree widely over their acceptability. For one expert, a wine with detectable evidence of Brett is unpardonably faulty, while to another, the same wine will be greeted as complex and showing a sense of place. To untangle this web, it is worth looking at the facts over which there is no dispute.
Brettanomyces has the rare distinction of bringing together the worlds of beer and wine. A strain, Brettanomyces claussenii, was first identified at the Carlsberg brewery in Denmark by Niels Hjelte Claussen in 1903. Claussen was investigating a batch of sour English beer, which explains why the yeast came to be named after both him and the Greek for ‘British fungus’. Innovative brewers realised that despite its association with faulty ale, Brett might contribute to the production of interesting beer. In 1908, a letter was sent to the editor of a Chicago publication called The Western Brewer: and Journal of the Barley, Malt and Hop Trades saying that the writer had been ‘advised’ to used the yeast to ‘improve the flavour and taste’ of their ale. The answer was that Brettanomyces was not a ‘commercial article’, but a ‘group of micro-organisms’ that can be isolated from… old English ales and that it is the ferment which gives to these beers their… taste and flavour’. The enquirer was told that 125cc of a Brett culture per barrel would be ‘sufficient’.
Ever since, brewers have taken a passionate interest in the contribution an intentional addition of Brett can make to some styles of beer, and its undesirability in others. Today, Chad Yakobson MSc, founder of the Crooked Stave Artisan Beer Project in Denver, enjoys a cult following for his Brettanomyces Project experiments into using Brett in Belgian-style beer fermentation.
Brett’s relationship with wine is less clear. The first time the two were scientifically linked was in 1940, when a researcher called M.T.J. Custers performed a first systematic study on 17 strains of Brettanomyces yeast and found one in a wine. Three-quarters of a century later, while studies have been conducted by scientists such as Pascal Chatonnet of Laboratoire Excell in Bordeaux, winemakers still have less understanding of the subject than brewers. All too often, wines with the tell-tale Band-Aid or horsey character are thought to be displaying ‘terroir’. In a 2005 Guardian interview, Chatonnet admitted that when he began to make wine in the 1960s, he thought brett was a typical character of wines from Graves. Now, he is clear that the yeast is actually the enemy of terroir because wines infected with it will all taste the same.
When discussing the smell and taste of Brett, much depends both on the precise strains of the yeast, their concentration, combination, and the style and age of wine in which they appear. One of the main yeasts, 4-ethylphenol (usually referred to as 4-EP), is associated with ‘Band-Aid’ characters, while 4-ethylguaiacol (4-EG) is more pleasantly spicy and 4-ethylcatechol (4-EC]) is the barnyardy villain of the piece. Some fruity, well-structured wines will conceal their Brett component more effectively than lighter styles – until the fruit component fades over time, allowing the Band-Aid or stable characters to emerge. Pinot Noir seems to be particularly susceptible to the barnyard character while Shiraz and Nebbiolo sometimes take on the spicy notes.
While awareness and understanding of Brett has grown in tandem with greater technical understanding, there is also no doubt that there is also more Brett around. This is explained by the trend towards picking riper grapes, higher pH levels, residual sugar, more barrel ageing, a move away from filtration and – especially among ‘natural’ winemakers - a dramatic reduction in the use of SO2. While Brett infections have been found in vineyards and on grapes, barrels are often seen as the major culprit in the spread of the infection in a winery, especially as wine is racked from one cask to another.
As Randall Grahm of the Bonny Doon winery in California told me, “a certain portion of one's barrels can well be infected and others not. It's certainly then a reasonable strategy to sterile-filter the infected barrels and not filter the others. But it seems that it is still very tricky to have real certainty about whether your wine has Brett or not, as the testing methods seem to be not 100% reliable.”
In recent times, the argument over the acceptability and even desirability of small amounts of Brett has been enlivened by the growing trendiness of unsulphured, unfiltered, wild yeast-fermented ‘natural’ wines. Supporters of these styles are generally far more tolerant of characteristics such as volatile acidity and Brett. Alice Feiring, the New York-based author of Letting Grapes Do What Comes Naturally, has written about “earthy/savoury” Brett or “sheepiness” and says that if it does not “overwhelm the wine” it’s “terrific”.
Feiring is not alone. Plenty of well-respected palates have admired wines like Château de Beaucastel in Châteauneuf-du-Pape, Château Musar in Lebanon and Henschke’s Hill of Grace, all of which have historically – in at least some vintages – been associated with Brett (www.meininger.de/en/wine-business-international/great-brettanomyces-taste-test).
Maar even terug naar de geschiedenis, een stukje bierhistorie van Shut up about Barclay Perkins:
Ron (patto1ro) Pattinson's When was Brettanomyces discovered? blog entry has more on the history, pre-Claussen. #6jesskidden, Sep 24, 2014 (www.beeradvocate.com/...brettanomyces-history.214099/):
Trawling through the Journal of the Institute of brewing, I stumbled upon a little article about Brettanomyces by R. B. Gilliland. It was a revelation.
I'd accepted that it was Claussen, working at the Carlsberg laboratory, who first discovered Brettanomyces in 1903.It turns out that's not the whole truth... Claussen may have been the first to publish about Brattanomyces, but he wasn't the first to find it.
On the face of it, a brewery in St. Petersberg seems an even more unlikely place to come across Brettanomyces than in Denmark. But, if you think about it, there is some sense to it. In the late 19th century, about the only beer being imported into Russia was strong Stout. Stuff that would have been aged and gained its distinctive flavour from a Brettanomyces secondary conditioning. Someone trying to replicate such a beer might well go looking for the secondary conditioing yeast.
As for Guinness, well, they're exactly the sort of brewery you would expect to have discovered Brattanomyces. In the 1890's Guinness still vatted a decent quantity of beer. Foreign Extra Stout was mostly a vatted beer, but a proportion of aged beer was also blended into Extra Stout and Porter. While in Britain this sort of long maturation was only used for the strongest beers, it was a vital part of all Guinness's products.
Why didn't Seyffert or Tullo publish? In the former case, it was most likely a commercial decision. If you'd cracked the way of turning any old Lager into aged Stout, you'd quite likely want to keep it to yourself. There was potentially lots of money to be earned from that knowledge. Perhaps there was the same consideration at Guinness.
That also might explain why Claussen did publish. Secondary conditioning wasn't really part of Carlsberg's business (http://barclayperkins.blogspot.nl/2013/06/when-was-brettanomyces-discovererd.html, http://barclayperkins.blogspot.nl/2015/05/brettanomyces-hero-or-villain.html).
The holder of the patent is N. Hjelte Claussen, the scientist who discovered brettanomyces at Carlsberg. I'm going to go ahead and hazard the observation that the Wiki site on his strain--brettanomyces claussenii--is wrong; it says he discovered the strain in 1904. Nice trick securing a patent on this technique a year before he discovered the actual strain.
I'll hazard a second observation as well: Claussen's scheme to pitch brett into lagers doesn't seem to have taken off. Sour lager (sauerlagern?)? Someone should give that a shot--there's a gold medal at the GABF waiting for the first brewery to perfect it (http://beervana.blogspot.nl/2012/01/ahead-of-his-time.html).
Er zijn 3 soorten van brett:
Here’s an overview of the properties of various types of Brettanomyces isolated from bottle-conditioned beers:
“Group 1. -21 strains fermented glucose, sucrose and maltose only. These strains agreed with the published descriptions of Brett. bruxellensis Kufferath et van Laer and were similar to authentic strains of this species. Brett. bruxellensis has been isolated from Iambic beer, from Cork porter, from French grape must and from Brazilian wine fermentations."
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 259.
Now the second group:
“Group 2. -11 strains fermented glucose and galactose only. These strains agreed with Peynaud & Domercq and were similar to an authentic strain of this species. Brett. schanderlii has been found in French and South African wine fermentations. It has not previously been reported as occurring in beer. "
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 259 - 260.
Interesting that this had previously only been found in wine, not beer.
This sounds like a weird one:
“Group 3. -12 strains fermented glucose, galactose, sucrose and lactose. This combination of fermentative abilities does not correspond with any established species. These strains are most like Brett. anomalus but differ from this species in that they ferment sucrose rapidly. A further study is being made of these strains and, if the differences are sufficient to establish the strains in this group as a separate species, this will be reported in a further communication. For the present these strains will be described as Brettanomyces sp. 1. It seems strange that so many strains unable to ferment maltose (Groups 2 and 3) should be found in beer, but Custers isolated Brett. anomalus, which also is unable to ferment maltose, from English beer. It was because of this peculiar circumstance that Custers gave this species the name "anomalus."”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.
You wouldn’t want that getting into your Milk Stout. Bottle bombs would be the inevitable result of the Brettanomyces chewing its way through the lactose (http://barclayperkins.blogspot.nl/2015/05/brettanomyces-hero-or-villain.html).
The compounds responsible for contributing certain sensory characters
to wine/beer are;
4-ethylphenol: Band-aids, barnyard, horse stable, antiseptic
4-ethylguaiacol: Bacon, spice, cloves, smoky
isovaleric acid: Sweaty saddle, cheese, rancidity
(http://societyofbarleyengineers.org/wp-content/uploads/2013/08/Peter_Perrecone_The_World_of_Brettanomyces.pdf)
There has been lots of good posts concerning the ‘discovery’ of Brettanomyces in the late 1800s/early 1900s; N. Hjelte Claussen is often attributed as being the person who ‘discovered’ Brett since he published on this matter.
While yeast as a living organism was not discovered until 1857 by Louis Pasteur, brewers and bakers were aware of yeast as a needed ingredient. British brewers were cognizant that ‘something’ was adding tartness to their stock ales and porters in the 1700’s. Another recognition of ‘something’ was that the IPAs of the early 1800’s would come out being exceptionally dry (very low final gravities) when they were aged in wooden barrels for extended periods of time. They did not know the specifics of the science (i.e., Brett living in the wooden barrels conducting a secondary fermentation within the barrel) at that time but the effects were certainly recognized.
Cheers!
#9JackHorzempa, Sep 24, 2014 Last edited: Sep 24, 2014
(www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
If we're taking about modern craft brewing and the proliferation of Brett, Chad Yakobson of Crooked Stave deserves a mention for sure. Outside of making delicious beers with mixed cultures and especially 100% Brett beers, his research on Brett was pretty groundbreaking, and he's written plenty on the subject. Historically, someone already mentioned Orval, but Courage Russian Imperial Stout was another famous example of intentionally adding Brett for conditioning.
#10afrokaze, Sep 24, 2014 (www.beeradvocate.com/community/threads/brettanomyces-history.214099/)
Iemand heeft ook een website genaamd http://brettanomycesproject.com/ over zijn scriptie (MSc.) en dissertatie:
The Brettanomyces Master’s Project took 18 months to complete from start to finish. While it might not have taken so long had I not been working 40+ hours a week as a brewer for nine of those months, I still managed to complete the work finishing all the writing and submitting the dissertation on July 23rd, 2010 (http://brettanomycesproject.com/msc-project-archives/).
Pure culture fermentation characteristics of Brettanomyces yeast species and their use in the Brewing Industry (http://brettanomycesproject.com/dissertation/) This study was conducted to evaluate the pure culture fermentation performance of eight strains of Brettanomyces with the objective to find characteristic compounds produced during fermentation. Colony formation and growth was initially observed on media agars recommended for use in the brewing industry with strong growth observed on MYPG, WLN, and CuSO4 agar medias. Cell growth during semi aerobic batch culture showed 2-phase and 3-phase growth patterns with maximum cell counts reached after 168 to 192 hours of propagation. Pure culture fermentations were conducted with multiple pitching rates and variation was observed in the different strains abilities to achieve adequate attenuation after 35 days. Longer time was needed for most strains except B. bruxellensis (BSI-Drie), which achieved 82.16% apparent attenuation with a pitching rate of 6×106 cells/ml. When the strains were pitched at a rate of 12×106 cells/ml a correlation was observed between final pH and final apparent attenuation, with a lower final pH resulting in greater attenuation. Fermentations were further conducted with wort pre-acidified with lactic acid at concentration of 100, 500, 1,000 and 3,000 mg/l. Higher initial concentrations of lactic acid had a significant effect, increasing the level of attenuation observed in each strain, while generally decreasing the secondary metabolites produced. Compound analysis of the fermented beers showed ethyl acetate, ethyl caproate, and ethyl caprylate were the significant esters produced with no isoamyl acetate detected throughout the study. Of the esters produced, ethyl caproate and ethyl caprylate were produced at levels previously unseen in fermented beer (http://brettanomycesproject.com/dissertation/abstract/).
