Day 371

Today started <sigh> at 8:30 a.m.  with Brewhouse Calculations. Apparently there was last-minute change in instructors for this course, and while the new teacher, Matt Howell, gets up to speed, Kevin Somerville has graciously stepped in for a few weeks. Kevin, our Brewing Ingredients teacher last year, is actually right in the middle of installing equipment in his latest venture, a new brewery in Niagara-on-the-Lake called Oast House, so it is very impressive that he has agreed to lend a hand at a time when he obviously has a lot to do.

Since we already know each other, Kevin didn’t spend time on introductions, but waded right into calculations. First up was the formula for determining how much grain is needed for a brew. Although homebrewers can (and do) throw grain into the mash and then wait to see what the final strength of their beer will be, it’s important for the professional brewer to be able to consistently brew his beer to a given strength, such as 5% abv. So the brewer needs to know exactly how much grain he or she will need. The formula is:

m = (Vc x sg x P°%) / (E% x (1-M%) x B%)

where:

  • m = grain desired (in kilograms)
  • Vc = the volume of cool wort (in litres) that you will end up with at the end of mash (However, wort is hot at the end of the mash process and takes up more volume, so to get the cool wort volume, you need to subtract 4% from your hot wort volume )
  • sg = your target specific gravity–that is, the amount of sugar you want in your wort. Since sugar is the yeast’s food source, this determines how strong your beer will be.
  • P°% = the specific gravity again, this time expressed in degrees Plato as a percentage
  • E% = the percentage of extract in your grain (coarse grind, dry basis)
  • M% = percentage of moisture content of the grain
  • B% = the efficiency of your brewhouse in extracting sugar from the grain, expressed as a percentage

So if we are planning a little 50L brew, and want to end up with a specific gravity of 1.044 (11°P), in a brewhouse with an efficiency of 87%, using grain with an extract content of 80%, and a moisture content of 4%, our calculation would be

(50 x 1.044 x 11%) / (80% x 96% x 87%) = 8.6 kg of grain needed

We also did the calculations using American weights and volumes, which adds a couple of extra steps to the formula, since those funny Americans have strange measures like barrels (weighing 258 pounds each) and gallons (which weigh 8.322 pounds). You really get to appreciate the “1 litre weighs 1 kilogram” metric system after a few of those problems.

We had to hand in three brew recipes to Jon Downing later today, so there was a mad scramble at the end of the class as students got out their proposed recipes and quickly recalculated their grist bills to see if the recipes bore any resemblance to reality.

Then it was on to History of Beer with Bill White. Bill worked for Labatt’s for 30 years as everything from a brewmaster to an educator with the Oland Specialty Program. For the past seven years, he has been a judge, writer, consultant and head honcho of his own company, Better with Beer. Bill’s course will cover the entire history of humanity from prehistory to the present, since as Bill said, “The history of the world flows on a river of beer.”

As Bill pointed out, some researchers believe that the need to grow barley for beer was what changed us from hunter-gatherers to farmers–and from there we started the climb to civilization. Although there is strong evidence for prehistoric beer making in Mesopotamia and Egypt, there is also evidence that brewing developed concurrently across the world in places as far apart as the Yangtze Valley of China, the Incan Empire of Peru and the sub-Saharan plains of Africa.

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