This is where I will try to post, as often as I can, on beer topics that are related to my beer, the beer I drink, and my beer education.

Wednesday, March 15, 2006

Day 33, Brewing Science

Today was long and very boring at times. I was totally lost on some of the biochemistry of the flavor compounds. I did find the discussion on high gravity brewing (HGB) to be pretty interesting, though I definitely disagree with its use because of some personal issues.
If normal brewing is done to 9 to 12 degrees plato, then HGB is done to 16 to 19 degrees plato on average. The idea behind HGB is simple; you brew, ferment and filter the beer at high gravity, and then add pure, de-oxygenated water prior to bottling. The beer is diluted based on alcohol content (i.e. from 7 to 5%). The advantages to this are mainly economic: more efficient use of vessels, increase in plant capacity, decreases labor, energy, and cleaning, and the beers are said to be more stable and smoother tasting. It also gives the brewer the opportunity to use it as a “mother beer”, adding more or less water, or color or hop extracts prior to bottling.
Disadvantages to this system are vast. If you exceed 20 degrees plato, the viability (i.e. Is the yeast alive?) and the vitality (i.e. How alive and vigorous is the yeast?) of the yeast will suffer. You may have to install a new plant to de-oxygenate the water used for dilution. The brewhouse efficiency will decrease appropriately. Foam stability tends to decrease, because the high gravity environment tends to precipitate out more proteins, some of which (the hydrophobic ones) are vital to foam stability. And most importantly, the customer would be insulted if he/she was to discover that they were being served watered down beer.
Apparently all the big breweries have converted to HGB, and the market is encouraging the microbreweries to make that shift next. Sierra Nevada (where I will be visiting tomorrow) continues to refuse to switch to HGB.


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