How to Beat a Persistent Infection
Maybe you borrowed a friend's fermenter to brew more beer, or a rabid squirrel dropped a berry in a carboy. No matter the root cause, something has crawled into your equipment. You've scrubbed and sanitized, but time and time again the visitor comes back to ruin your beer.
Taking copious notes helps pinpoint the cause. With good notes, you can determine the infection vector.
Cleaning, Sanitizing, and Killing
Your first great inclination is to clean everything in sight. Here are a few simple rules to follow:
Hoses/buckets/stoppers/airlocks — Thanks to miniscule scratches, plastic is always suspect in a brewery. Start by chucking anything plastic that may have infected a brew or come in contact with one. Continuing batch problems aren't worth the $1.50 to replace an airlock.
Tear everything apart — When an infection appears, tear everything apart and inspect it. The mold example above happened before. Remove hoses from racking canes to clean where they cover up. Pull apart your manifolds, spigots, airlocks, and kegs.
Clean twice — With everything apart, break out the brushes. Soak every part in cleaner and scrub them. Leave everything glistening and wait a week to promote passivation.
Change sanitation practices — Eliminate your usual shortcuts and expose the visitor to a never-before-used sanitizer. A simple change can work wonders in your brewery. Take your metal parts and boil them for ten to fifteen minutes. You can bake and very slowly cool glass items. (Follow the oven sanitation method for bottles.)
Testing to Find the Culprit
Never underestimate the value of intelligence in fighting an enemy too small to see. When a teardown has failed, you need additional data.
The basic detection test you'll use is the “Wort Stability Test.” Each step of the brew day, take a sanitized sample and store it. Buy test tubes for easy-to-sanitize storage.
Uncap a sanitary tube, add your sample,152 and cap. Make sure any sampling “thief” is clean and sanitary first. Stick the filled tubes upright some place cool and out of the light. Check every few days for obvious signs of infection. When the beer is ready, sample it and check the tubes if an infection hits. Open the tubes, smell them, and taste them. Any show signs of your infection? If you find one, you'll know the bacteria hit the beer at that stage.
When do you sample the beer? Take samples when: the beer is finished boiling and leaving your pot; the beer is finished chilling; the beer is in the carboy, but not pitched with yeast or oxygen; after pitching; on transfer to secondary; on transfer to bottling or keg. Make sure to label each sample so you'll know their origin. Post-pitching samples should be treated with cyclohexamide to kill the yeast.
Tasting is vital to tracking your infection source. At every step of fermentation, take a taste and note any flavors you find.
If the stability tests and taste tests point to a culprit, refocus your attention on that area.
Fixing the Problem Now
An off flavor or aroma doesn't mean the beer is trashed. A deft and clever brewer can adjust the taste of their beer to hide or distract drinkers from a flaw.
When considering approaches, think about the effect of the flaw on the beer. For instance, a brewer had a batch of beer that was lightly astringent with aromas of cooked corn from DMS; to correct and hide it, she added an apricot extract. The sweetness of the apricot aroma played off the sweet corn while the acidic flavor hid the astringency.
Common Post-Fermentation Adulterations
Body by powder — Beers lacking body can be punched up with additions of maltodextrin powder or lactose for a little sweetness. Boil 4 to 8 ounces in water for fifteen minutes before adding.
Color — If your stout ends up looking more like brown ale, you can turn to a German malt colorant called Sinamar. It can make a blonde beer coal black. Smaller doses add reddish-brown colors.
Fruit — The addition of fruit can cover a multitude of problems, and folks love the flavor. While whole fruit is great, it's not always practical for troubleshooting situations. In addition to the sugarless extract route, sweet fruit liqueurs can provide the needed cover-up.
Hops — Caught early enough, a strong dose of dry hops or hop tea can cut through a sweet beer or provide complimentary spicy or fruity aromas.
CO2 scrubbing — Some aromas can be scrubbed away or reduced by bubbling CO2 through the beer. Keg the beer and close the lid. Swap the CO2 tank fitting for a black liquid fitting. Set the regulator to 5 psi and attach to the liquid post of the keg. Let the gas flow and crack the pressure relief valve. Run the gas for a minute and check the aroma. Repeat as needed.
Blending — The patient can brew a second batch that overemphasizes an opposite character and blend the beers. A beer that's too bitter without balance can be balanced by a second batch pushing malt.
