Day 219

And so, it has come to this: The Last Day of First-Year Classes.

Duh duh duhhhhh!

And yet, it was a pretty typical Friday: lectures, lectures and more lectures, all from Mark Benzaquen.

First up was the final Sensory Evaluation class. The topic was evaluation of our raw ingredients: water, malt, hops, yeasts and gases.

I thought sensory evaluation of water was a bit odd, but of course, the brewmaster always wants to make sure that the water coming into the brewhouse is clear, free of floaty bits and sediment, has no odours, and doesn’t taste like iron or sulphur (common for water drawn from wells and other ground sources), or have tangy or sour tastes that could indicate microbiological contamination.

Malts can be examined for colour and appearance. Cracking a kernel open with your front teeth indicates good friability–an unmalted kernel of barley is extremely tough and would probably break your teeth if you persisted. Once open, you can examine the internal appearance as well–a bright white kernel indicates a well-modified grain, a greyer colour may indicate undermodification during malting. And of course, you can chew the grain to get an idea of its flavour. Overall, your bag of malt should be free of other grains such as rye, and of course, there should be a complete absence of insects or evidence of mouse depradations.

Hops can be rubbed between your hands and then “nosed” to get an idea of the flavours they will be adding. You can also make hop teas using hot water–which we did.

Even oxygen and carbon dioxide can be smelled (carefully) for off-aromas. Carbon dioxide can have traces of sulphur dioxide (rotten eggs) left over from its manufacture, and oxygen can be contaminated with aerobic bacteria, neither of which you want in your beer.

On to the final Microbiology lecture, where we picked up from yesterday’s lecture about cleaning. Today we continued with CIP (Cleaning In Place), talking about the proper techniques for cleaning, line cleaning, how to avoid problems in line cleaning when designing your brewery plumbing, and the final step to cleaning: sanitation.

With cleaning out of the way, we learned how to take proper samples for microbiological testing, the various methods to see if the sample is contaminated (immediate detection, predictive testing, direct plating and membrane filtration). We also looked at some of the more popular growth media you can use, including some that encourage certain types of microorganisms to grow, others that discriminate against certain types, and still others that neither encourage or discriminate, but do differentiate what is growing via colour changes, or clear/hazy appearance.

All of these take normally take 5-7 days to allow colonies to become visible, but if you are in a rush, you can try to hurry the process, either examining your plates under a microscope before colonies become visible to the naked eye, or by the use of optical brighteners that fluoresce in the presence of certain microroganisms before the colonies are visible to the naked eye.

End of Microbiology. Whew!

On to the final Chemistry class, where Mark had a few words–okay, a lot of words–to say about the chemistry of filtration.

Then on to the types of tests we can run on beer in the bright tank (calculated original extract, real extract, % alcohol, clarity/turbidity, colour, oxygen content, CO2 content, foam stability, bitterness level and beer haze stability, and levels of diacetyl and other flavour-active compounds).

And that was all she wrote for first year. Up next: five exams.

To the books!

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