Sunday, September 6, 2009

The brewing season is nigh

I recently purchased a cool, new gadget for the brewery: a refractometer. This one (from William's) measures sugar content from 0-32 Brix. I hope it will help me keep better track of the mash run-off. I don't get anywhere near the yields I think I ought to so I need to get a better look at the process. I know I should take a little more time with the dough-in, and I could probably improve mash efficiency with more uniform mash temperatures as well. But I don't really need an excuse to get a new instrument for the lab. These things work on refraction--the higher the concentration of sugar in the solution the more the light bends. This is a regular phenomena and a measurment scale can be calibrated empirically. The Brix scale goes back to the 1800s and is an improvement on the original tables of the German chemist Karl Balling. The scale reports "% sucrose per 100 grams of solution," that is, a solution of 15 g of sucrose in 85 grams of water (100 g total) would read 15 ºBx. Beer wort is not sucrose, of course, but the malt sugars behave similarly--their concentration determines the refractive index of the solution. So a brewer can put a drop of wort on the lens (the angled part on the right side of the photo) and look through the eyepiece (on the left, with the rubber cup), and get a reading. You need to be outdoors in bright sunlight. A dark/light boundary will form on the scale marking the degrees Brix. Mine is a low-cost, made in China device, but it will be accurate (+/- 0.2%) enough for my fairly rough purposes. Stay tuned--cool weather is on the way and FSB will be back up for the fall.

a.d. VIII Id. Sep.

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