Saturday, 23 May 2015

Brettanomyces – hero or villain?

I thought this article about Brettanomyces would interest you. It contains some great stuff.

First, an overview of Brettanomyces and its role in brewing:

“Brettanomyces spp. have long been known as important factors in the production of condition and flavour in certain high-gravity beers and in lambic beer. They have also been mentioned as possible spoilage organisms in beer but have generally been considered as of little importance in this connection. Thus Wiles stated that Brettanomyces had only once been reported as a spoilage organism of beer, and that although Brett. bruxellensis was sometimes detected it was not of common occurrence and was unlikely to be a cause of spoilage. On the other hand, Shimwel1 found a Brettanomyces to be the cause of a fret in beer and suggested that it might be widely encountered as a spoilage organism. It has been stated that Brettanomyces can cause a mawkish "nose" and turbidity in beers of original gravity less than 1060.”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 257.

Now isn’t that fascinating? That Brettanomyces produces a funny flavour in beer under 1060º. Why would that be? They seem undecided on whether Brettanomyces was a common spoilage agent. By ‘fret” they mean a too vigorous secondary fermentation in the cask.

I’ve mentioned this before. Although Claussen (of Carlsberg) was the first to publish about Brettanomyces, it had been discovered earlier:

“Occurrence of Brettanomyces.—The earliest reference to Brettanomyces, or secondary yeasts, was in a patent for the use of these organisms for the preparation of English beers which was taken out by Claussen in 1903. In a paper to the Institute of Brewing in 1904, Claussen described the importance of Brettanomyces for secondary fermentation and the production of the characteristic flavour of English stock beers. Claussen did not give a detailed description of these organisms, which he included in the genus Torula. Shortly after this, Seyffert of the Kalinkin Brewery in St. Petersberg announced that he had isolated a "Torula" in 1889 from English beer which produced the typical "English" taste in lager beer, and which was similar in other respects to Claussen's Brettanomyces. In 1899 J. W. Tullo, in the Chemist's Laboratory, Arthur Guinness Son & Co. Ltd., Dublin, had already isolated two types of "secondary yeast" from Irish stout, and in an unpublished report described the characteristics of these yeasts and their importance in secondary fermentation.  At this time the "secondary yeasts" were important constituents of the flora of all stock beers, and in particular of those beers, designed for the export trade, which under-went long maturation in the brewery. These export  beers  depended indeed on  the "secondary yeasts," not only for their characteristic flavour but also for the production of condition in bottle by means of their ability to ferment higher polysaccharides which the "primary yeast" could not ferment.”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 257.

If I tell you that secondary fermentation  was very important at Guinness because they still vatted Stout, particularly their export version. Meaning that information about the process had commercial value. The same was probably true of the brewery in St. Petersburg.

Here’s something about the nature of Brettanomyces.

“Properties of Brettanomyces.—The cells of Brettanomyces are small, oval or round, frequently with a pointed end (ogive).  In some strains elongated cells and branched chains ("trees") are frequently seen.  On suitable media most strains show a tendency to form pseudomycelium.  In malt extract Brettanomyces spp. grow slowly but give a high final attenuation' and a characteristic aroma.

Under aerobic conditions they produce considerable acid; this may be the reason why malt-agar cultures have a short life. In agar-streak cultures they give yellow or brown raised growth. The genus has always been considered anascosporogenous, but van der Walt & van Kirken have recently reported sporulation in a number of species which would necessitate the placing of the genus in another family. The fermentative abilities of the various strains in the species as described by Lodder & Kreger-van Rijn and by van der Walt & van Kirken are given in Table I. One of the most interesting characteristics of the metabolism of Brettanomyces is that young aerobic cultures exhibit a negative Pasteur effect.  That is, they have a very much stronger fermentative ability under aerobic conditions than under anaerobic conditions, in contrast to other yeasts. Another important characteristic of the genus is that secondary products of fermentation accumulate to a much greater extent than is the case with Saccharomyces. Ethyl acetate, glycerol, acetic acid, succinic acid and 2,3-butane-diol have been estimated by Peynaud & Domerce in the completed fermentations with Brettanomyces.  These authors consider that ethyl acetate and acetamide are the two main organoleptic products of Brettanomyces fermentations, but that some strains may also produce a butyric smell.”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 258.

Reverse Pasteur effect? That’s a new one to me. Maybe that’s why Brettanomyces scavenges oxygen so well in bottle-conditioned beer.

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.

But its odder that so many of the strains were unable to ferment maltose. Though, thinking about it, that’s probably preferable fore brewery use. It means that the Brettanomyces can’t take any part in primary fermentation. Just what you’d want in the case of running beers.

Here’s a table of what the different types of Brettanomyces can ferment:


Fermentation of
Species Glucose Galactose Sucrose Maltose Lactose Raffinose Trehalose Melibiose Melezitose Cellobiose
1. Brett. Bruxellensis* Kufferath & van Laer  .. + + + + +
2. Brett. Anamalus Custers + + + + + +
3. Brett. Claussenii Custers + + + + + 1/3 + + +
4. Brett. Intermedius ** Peynaud and Domercq, van der Walt  + + + + + + +
5. Brett. Schanderlii Paynaud & Domercq + + +
* The strains known as Brett. bruxellensis var. not -membranaefaciens Custers, Brett. bruxellensis var. lentis Custers, and Brett. lambicus Kufferath & van Leer, are included in the species Brett. bruxelensis as suggested by van der Walt & van Kirken. 
** This strain was named Brett. vini by Paynaud & Domercq. It was found to be identical with Mycotorula intermedia isolated by Krumbholz & Tauschanoff and was re-named Brett. intermedius by van der Walt & van Kirken.
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 259.

I’m a little shocked that they were able to find 11 naturally-conditioned bottled beers in 1961. I though the technique was pretty much dead by then. Or maybe they weren’t 11 different beers.

Many of the bottles from which the yeast was isolated contained multiple strains of Brettanomyces:

“The distribution of the individual strains from the 11 bottles is given in Table II, from which it will be seen that from 5 of the bottles only one species of Brettanomyces was recovered; in all the other bottles two or more species were found. The infection therefore regularly occurs as a mixture of species of Brettanomyces.”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.

Here’s a summary of the strains of Brettanomyces found per bottle:

Bottle No. No. of strains studied No. of strains of Brett. bruxellensis No. of strains of Brett. schanderlii No. of strains in Brettanomyces sp. 1 group
1 4 0 4 0
2 4 2 1 1
3 4 1 3 0
4 4 0 1 3
5 4 2 2 0
6 4 4 0 0
7 4 2 0 2
8 4 4 0 0
9 4 4 0 0
10 4 2 0 2
11 4 0 0 4
Total 44 21 11 12
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.

I like the fact that they carried out taste tests based on bottle-conditioned beers inoculated deliberately with their strains of Brettanomyces.

“Tasting experiments were carried out with 36 of the pure cultures of Brettanomyces isolated from beer. In these tests the culture of Brettanomyces was added to beer at bottling at the rate of about 5 cells of Brettanomyces per 100 cells of culture yeast present in the beer. The beers were naturally conditioned at 18° C. and, after 2-5 weeks, they were tasted against a control of the same beer which had been bottled at the same time but which contained no added infection. The results are summarized in Table III for each of the three species. The taste of the infected beers became more objectionable as the beers became older but, for simplicity, the results of the tastings at different periods have been combined. It is clear that Brett. bruxellensis has much the worst effect on flavour of beer, although the other groups have an appreciable deleterious effect. The flavours most complained of in the infected beers were "harsh," "strong after-bitter," "mawkish" and "old beer flavour."”
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.

Here’s the table of those results:

Species Strains Times tasted Better than control Equal to control Worse than control Much worse than control
Brett. Bruxellensis 19 133 0 15 39 46
Brett. schanderlii 8 58 2 53 41 4
Brettanomyces sp. 1 9 46 0 37 61 2
Journal of the Institute of Brewing, Volume 67, Issue 3, May-June 1961, page 260.

It doesn’t look like the Brettanomyces character was much admired by the tasters. The infected samples were almost always judged as no improvement – in some cases much worse – than the non-infected ones.

Of course, it could just be that the tasters weren’t accustomed to Brettanomyces character in beer. It would be fascinating to know what tasters would have thought of the infected beers 100 years earlier. They might actually have liked them.


Unknown said...

Schanderlii and Intermedius aren't names of current Brett species, as far as I know. I wonder if they were renamed to other Brett species later on?

Kristen England said...

Always see what mycobank says.

Straininfo is good to for related organisms.

Once you have your strain info then you can find it on ATCC.