Free Range Haggis

Studying, Eating, and Drinking in Scotland


Leave a comment

Growing Brettanomyces Cultures, Let’s Get Inoculated.

The past few days have been pretty intense in the lab. There is lots of prep work that needs to be done: autoclaving different medias to grow cells up on, pouring differential plates for strain analysis, making solutions, etc. A few set backs have pushed my start up date back a little, but now I should be all ready to roll tomorrow.

The assay I’m working with was originally developed for studying premature yeast flocculation, or PYF. This phenomenon causes some yeasts to randomly fall out of solution before primary fermentation is finished causing residual sugars to remain in solution, and possible off-flavor development. Some believe that PYF is caused by a fungal infection which begins in the germination process as a result of excessively high CO2 exposure, but thats another story for a different day. This assay has been subsequently accepted as the standard for comparing yeast fermentability characteristics by the American Society of Brewing Chemists (ASBC).

Like I said before I’ll be using a few different yeasts in my project this semester. Wyeast Laboratories in Oregon have graciously provided both a Brettanomyces lambicus and a Brettanomyces bruxellensis strain. In addition, I’ll be using additional B. lambicus and B. bruxellensis strains of my own. Finally as a control I’ll be using an American Ale yeast.

 

Plating and Propagation:

So far all strains have seemed to grow very well on YPD plates, which use dextrose as a sugar source. For the YPD plates I use in this project, I follow this recipe:

10 g/L Yeast Extract

20 g/L Bacteriological Peptone

20 g/L D-glucose

1.2 % w/v technical agar.

 

These plates seem to support good, rapid growth of both Brettanomyces and Saccharomyces strains

 

Shows good development of colonies after 5 days of growth.

Good development of colonies after 5 days of growth at 25 C.

 

The assay begins with a step up propagation in YPD broth. Initially 3-5 single colonies are removed from the streak plates like those above and are used to inoculate 50 mL of YPD broth in a 125-mL Erlenmeyer flask. This flask is grown on an orbital shaker at 100 rpm at 25 C for 24 hours, at which point the cells are centrifuged, washed, and used to inoculate a two more 250-mL flasks containing 100 mL YPD broth at a cell density of 1.5 million cells/mL. These flasks are again placed in a shaker for another 24 hours. At this point I’ll have enough cells to pitch into my test tubes.

 

Pulling colonies off of YPD plates for inoculation into propagation media.

Pulling colonies off of YPD plates for inoculation into propagation media.

 

Some things to consider:

Very little research has been done on primary fermentation of Brettanomyces. I’m hoping to look at the effects of dissolved oxygen, initial pH, growth medium, and propagation time as potential parameters for my growth trials. Brettanomyces is a notoriously slow fermenter, but with any luck maybe I’ll be able to figure out how to coax it along a bit more rapidly while retaining all the funky goodness this yeast brings to the table.

 

 

Advertisements


Leave a comment

And So It Begins…. Brettanomyces Fermentation Speed Analysis

Hello!

This week has been a big one. I was finally able to get out of the library and into the lab to begin experiments for my dissertation. I’ll be working with several Brettanomyces yeasts this summer to determine if their primary fermentation kinetics mirror those of traditional ale and lager strains. My advisor, Dr. Alex Speers, has developed a miniature fermentation assay for determining fermentation speeds and modeling them with a “simple” logistical equation. Because Brettanomyces species are so, well… funky… I’m interested in seeing if they metabolize sugars in the same way that their more traditional counterparts have been shown to do. After the initial experiments are complete I should have enough data to show that they do ferment similarly to ale and lager strains, or if not, I’ll be able to create a new equation to describe the new fermentation model. The second step will be to monitor the change in fermentation as a function of changing pH, sugar polymerization number, available nitrogen, or maybe even the presence of Maillard reaction products.

While attending classes at Heriot-Watt University, I’ve been lucky enough to run the Alpha Project nano-brewery associated with The Hanging Bat Beer Cafe. It has been really helpful to experiment with the different brewing parameters we’re learning about in class and see how they affect the downstream product. In addition to running my own practical experiments in the brewhouse, I’ve also been able to help with food and whisky pairings, and give beer knowledge training sessions to staff and customers. It turns out I like to teach significantly more than I thought I would, it’s fun to turn people on to something you have real passion for.

Anyway, recently I’ve been experimenting with the practical aspects of both primary and secondary fermentation with Brettanomyces yeasts. My classmate, Jonathan Hamilton, and I collaborated on a Saison recipe that used citrusy hops, a shed load of seville orange zest, and was finished with a 16 week secondary fermentation with Brettanomyces bruxellensis. It’s going on tap tonight at The Hanging Bat, I can’t wait. The other Brett project I have going at the moment is a 1.072 Belgian Pale Ale. This beer is fermented with a really nice Brettanomyces lambicus strain, that gives it a rich (but still subtle), cherry-pie-like aroma. This beer will be featured in a pairing event featuring 5 beers that I’ve brewed and 5 whiskies from Compass Box blending house. Should be crackin. I’ll keep you posted.

Be on the look out for more Brettanomyces related posts in the next few days!

 

 

 


3 Comments

Lambic Beer

I hold lambic in the highest regard. The tradition that surrounds this special beer is wonderful. Brewing one of these styles truly is one of the dark arts of brewing. The complex microflora seen in lambic fermentations are all traditional “beer spoiling” microbes. Things that brewers have nightmares about. These beasties can be hard to kill, hard to isolate, and worst of all some of them can outcompete your house yeast.

Lambic is controlled legally by an appellation controlee much like champagne. This restriction states that a beer cannot be called a lambic if it has not been brewed within a certain radius around Brussels. The mystique surrounding this beer has produced rumors suggesting that there is “something in the wind” in this area which produces the best microorganisms for production of this beer. A growing number of American craft brewers are beginning to produce “lambic-style” beers inoculated in open “cool-ships” much like the traditional belgian brewers. The results are looking good so far!

I’ve uploaded a paper I wrote last semester I’m quite proud of. Here I look at lambic fermentations, and explore the question: is there something in the wind around Brussels, or can a authentic tasting lambic-style beer be brewed anywhere?

Lambic