Brewing Beer with Science: Embrace Your Inner Nerd

BYOB by | Jan 2009 | Issue #24
Illustration by Scott Murry

I’m a sucker for the old mad-scientist movies—Jacob’s ladders arcing in the background with formulas bubbling away. My pursuit of science was hampered by my mom’s reasonably rational fear of handing me a chemistry set. But now, I can don a lab coat, play Dr. Frankenstein or CSI tech, and torture my beer for scientific fun. So, “Walk this way…” and let’s see what sort of science we can bend to our will.

Equipment: Magnetic Stir Plate
Lab work involves a ton of stirring. Unless you’ve got Popeye arms and nothing to do for a few days, you’ll need a stir plate. A stable platform hides a magnet rotated by a fast-moving motor.  To do something useful, drop a Teflon-coated magnet into a vessel of your choice (a growler or flask) and stand back. The Teflon bar magnetically couples to the whirring magnet below, inducing a stirring action and vortex in the vessel.

With just a gentle vortex, a stir plate grows yeast nearly four times more viable in a starter than the old shake-and-rouse method. Ditch the airlock and cap the jug with sanitized foil. That alone makes a stir plate worth the time spent trolling eBay or LabX for a good deal ($15-$40) or learning to rig a muffin fan and magnets into a homebrewed stirrer. Search online for plans.

Testing 1 … 2 … 3 … Sibilance, Sibilance
All the flasks, tubes and whirly thingamabobs don’t make a lab useful—that’s the job of the tests. Here are three common, easy and handy tests that can help you put a little scientific spin on your brew.

Forced Ferment
When exposed to massive heights of stupidity or new ingredients, yeast strains behave in unexpected ways. Wouldn’t it be nice to know how far down your yeast will go? With a stir plate and a sanitized vessel, discovering the lowest achievable final gravity is a snap.

After pitching the yeast and mixing it throughout the wort, draw a pint of yeasted wort with a sanitized thief. Add the stir bar and wort to a sanitized vessel and cap with foil. In a warm area, gently run the stir plate until visible fermentation signs have abated. Take a hydrometer reading and you’ll have your beer’s absolute minimum final gravity. Unless you ferment your carboy warm on a stir plate that stirs the whole mass, the beer will end up a few points higher than this reading.

This month’s recipe, a “best of show” winner in the past, was one of the first times I’d used a forced ferment test. Knowing the best FG encouraged me to put extra yeast and time into the brew to push it from its initial higher terminal gravity.

Forced Diacetyl Test
All yeast and bacteria produce the precursors to diacetyl, which becomes apparent after oxidation. Like most chemical reactions, oxidation is driven faster by the application of heat. To find out if your beer or yeast has a diacetyl problem, draw two samples of fermented wort. Cool one sample and heat another sample in the microwave for two minutes. After sitting for 30 minutes, cool to match the unheated sample. Smell and taste the two samples: If the heated one is buttery, consider warming the beer up and adding some yeast to chomp the diacetyl into odorless butanediol. Lager strains in particular may need a warm diacetyl rest before lagering.

Wort Stability
Got creepy crawlies ruining your beer? Find out where they’re coming from with a stability test. Sample the wort post-boil and post-chill, and hold at room temperature in sanitized test tubes. If you can make it 72 hours without haze, your sanitation is superb. Get your hands on cycloheximide, a yeast killer; add it to some fermenting beer in tubes to check on the sanitation of various stages of the ferment (e.g., post-pitching, start of secondary, start of packaging).

For 5.5 gallons at 1.111 OG, 1.023 FG, 68 IBU, 17 SRM, 11.8% ABV

Malt / Grain
15 lb. domestic two-row malt
2 lb. Maris Otter malt
2 lb. Scottish Crystal 55L
1 lb. Caravienne malt
1 lb. biscuit malt
1 lb. brown sugar

Extract brewers: Substitute 11 pounds of LME or 8 pounds of DME for the 15 pounds of domestic two-row malt.

Saccharification rest at 150˚F for 60 minutes.

1.50 oz. Target (pellets) | 8.8% AA | 0 minutes
2.00 oz. Fuggles (pellets) | 5.00% AA | 30 minutes
1.00 oz. East Kent Goldings (pellets) | 4.75% AA | 5 minutes

Wyeast 1275 Thames Valley Ale (for primary fermentation)
White Labs WLP001 California Ale (to finish)

2 tsp. yeast nutrient