MBAC 100th Anniversary Conference: Part 1

A couple of weeks ago, I attended the Master Brewers’ Association of Canada (MBAC) Annual Technical Conference. What made this one a bit special was that the MBAC was founded a century ago. Unlike the Ontario Crafter Brewers (OCB) Conference last October, which included seminars about marketing and event planning, the MBAC conference had a strictly technical focus — how to make beer, and how to make it better. Here is a summary of the various seminars.

Design of Fermentation and Maturation Tanks (Michael Kurtzweil, Ziemann International)

Ziemann is a German firm that manufactures fermentation tanks of all sizes. I remember them most for the tanks they made in 2010 for Molson — six massive 4500 hL tanks. (Each could hold about 1.4 million bottles of beer.) The tanks were shipped across the Atlantic to Hamilton (right next door to my town of Burlington), then put on trucks and then slowly and gingerly moved along back roads to Molson’s Toronto brewery. One of those back roads was about 2 km from my house. The move took ten nights, and required approval from the province of Ontario and six different municipalities since it involved lifting up hundreds of telephone, cable and hydro wires at intersections, as well as temporarily moving stoplights.

Michael Krutzweil’s first remark about buying fermentation tanks was that master planning is essential right from the beginning. Rather than thinking small and then scrambling for more fermentation volume, he advised brewers to “Think big, and start small”. Rather than ordering a tank when you need it, he advised us to plan ahead to when we think we’re going to need it, and order it well in advance to lower costs. This past summer I had personally seen several small breweries out in B.C. that had just opened their doors and were already trying to shoehorn more fermenters into a limited space because of unexpectedly robust sales, so this seemed like good advice.

When planning your tank farm, think about tank location. Are they going inside or outside? If outdoors, are they shiny showcase tanks, designed to be admired by the general public? Or are they going to quietly sit in a back lot, unseen?

Whatever the case, Michael suggested that you spend the money to ensure they are held high enough off the ground so that there is lots of working room underneath. Later on, as your brewery grows, this will allow you to install a pipe fence underneath them. (A pipe fence is a permanent grid of pipes and valves that allows you to move wort and beer hither and yon without stopping to attach and detach rubber hoses and pumps.)

What else should you plan on for the future? Flexibility seems to be the key:

  • If you increase the pressure capacity of your fermenters to 1.5 to 2.0 bars, the tanks can also be used as bright tanks to carbonate the beer.
  • Many tanks have pipes for water, cleaning solution, CO2, etc. welded directly to the top of the tank. However, Michael suggested having a removable dome plate bolted to the top of your tank instead. That way your pipes aren’t welded directly to the tank. Later on, if you want to change the arrangement of pipes or even the number of pipes, you simply replace the dome plate rather than replace the entire tank.
  • Speaking of a dome plate, what if you made the dome plate out of polyurethane rather than stainless steel? Some of New Belgium’s brewers found stainless steel dome plates too heavy to lift, but polyurethane plates were considerably lighter, and apparently have not affected performance.

Other things to consider for the future include insulation, glycol jacketing, access to the top of the tanks (ladders or catwalks?), security against earthquakes and high winds, and how new tanks are going to be moved to the brewery, especially the very large ones.

Yeast Management (Christopher White, White Labs)

White Labs is one of two major yeast suppliers in North America, so getting Chris White at the conference was impressive. The first point he addressed was the question of reusing yeast. Because yeast reproduces, it is theoretically possible to use the same batch over and over again forever. However, a batch of yeast can lose its efficacy over time due to mutations, lower viability and a loss of vitality; most breweries opt to replace the entire batch of yeast after a set number of uses (often ten batches). Chris says it all depends on how the brewery handles the yeast during

  1. Storage,
  2. Propagation and
  3. Pitching

1. Storage

When storing yeast, apparently the key to keeping maximum flavour and stability is to avoid changes in the environment and or environmental stresses — these will force the yeast to rapidly adapt to the new environment, causing mutations. Keeping the yeast in an anaerobic environment at -80°C will avoid both growth and mutation.

2. Propagation

During propagation — growing the yeast from a single test tube to 100 litres or more —  it’s important to get started soon after thawing out the yeast — never leave it sitting in a Petri dish for months at a time. Fresh wort is often used as a growth medium — this adapts the yeast to the stuff it’s going to be swimming in for the rest of its life, and wort also has all the nutrients yeast requires for growth. However, add the yeast to as small a volume of wort as possible — this reduces the risk of microbial infection due to competition for scarce resources. And remember to constantly agitate the flask to improve circulation of nutrients and oxygen. (Yeast need oxygen in order to grow rapidly). Chris cautioned that your lab has to be completely aseptic: tiled walls and floor, foot baths, HEPA air filtration, UV lights, and positive air pressure. And he suggested when propagating that you avoid volume increments of more than 10:1 during each step or forcing growth too rapidly.

For instance, he suggested that if we started with 10 mL of yeast and kept to volume increments of just 10:1, we could get as much as 100 litres of yeast in just over a week:

  1. Add 10 mL of yeast to 8°P wort and aerate and agitate the wort at 25°C for 1 to 2 days
  2. Move 100 mL of this slurry to a larger container of fresh 8°P wort and aerate and agitate the wort at 25°C for another 1 to 2 days
  3. Move 1 L of this slurry to a larger container of stronger wort (12-16°P) with more aeration and agitation at 22°C for yet another 1-2 days
  4. Finally move 10L of this to a very large container of 12-16°P wort for 2-3 days at 22°C.

Follow these four steps and in 5-9 days, you should have 100 litres of yeast slurry ready for use.

Chris also threw in some other considerations:

  • Using pure oygen rather than air will produce healthier yeast with thicker cell walls.
  • Watch for sources of contamination — when you are plating yeast, for instance, air-borne microbes can infect the Petri dish.
  • The wort temperature during propagation is usually higher than wort temperature during actual fermentation. Chris advises that towards the end of propagation, wort temperature be decreased so that, again, the yeast has a chance to gradually adapt to actual working conditions without being forced to mutate.
  • During propagation, transfer yeast to larger containers during its active growth phase (after 1-2 days), not after active growth has stabilized.

3. Pitching

Yeast can usually be used 5-10 times without problem. The usual pitching concentration (which I remember from Microbiology classes) is about 107cells/mL/°P. That is, about 1 million cells per millilitre of wort for every degree Plato of sugar — the more sugar there is, the more food there is for yeast cells, so there can be more yeast cells per millilitre.

(How do you estimate the concentration of yeast cells if your brewery doesn’t own a microscope? Put some yeast slurry into the fridge and let it cool for a day. The yeast will fall to the bottom of the container and form a thick white goo, while the liquid floating on top will be clear. If the yeasty goo makes up about 1/3 of the container, your concentration of yeast cells is (very) approximately 10 million cells per mL.)

If not handled properly, yeast can become infected by other microbes such as pediococcus or lactobacillus. You can “wash” the yeast with dilute acid, killing the microbes, but this has two effects. One is that it will also kill off some yeast cells, lowering your yeast’s viability. The other problem is that once you have acid-washed your yeast, it seems to become more susceptible to infection — from that point on, you may have to acid wash that batch every time you want to reuse it.

Lastly, Chris took a question from the floor about using olive oil during fermentation rather than oxygenating the wort. (You add oxygen to wort in order for the yeast to use the oxygen to construct lipids that can then be used to build cell walls. This allows for rapid and healthy reproduction. By adding olive oil to the wort rather than oxygen, the theory is that the yeast cells will use lipids directly from the olive oil rather than having to build them; hence, no need for oxygen.) In answer to the question, Chris replied that New Belgium had done some experiments with olive oil and had subsequently measured increased ester levels (fruity aromas) in the resulting beer, but the esters did not reach levels detectable by the human nose. The answer seems to be that the idea requires further research.

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One Comment on “MBAC 100th Anniversary Conference: Part 1”

  1. Canageek Says:

    Do breweries use techniques like working ‘under the flame’ to protect the yeast? We did a lot of that when I was with a biochem lab.


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