Homebrew Fermentation Do’s & Don’ts

Probably the most entertaining part of homebrew (other than drinking the finished product of course) is fermenting your brew. Don’t get me wrong; I love all parts of homebrewing except the clean up. To me, fermentation is fascinating and entertaining. It’s also critically important to brewing a quality beer, so let’s discuss some fermenting do’s and don’ts.

Pre-Fermenting Do’s & Don’ts
DO be extremely diligent to start with a clean and sanitized fermentation vessel. DO clean with the appropriate cleaner for the specific fermenting vessel you are using. Not all cleaners are appropriate for all types of fermenters. For example, if you are using a PET plastic carboy or bucket, DON’T use abrasive cleaners that can scratch the plastic. Scratches can harbor bacteria that can be very difficult or impossible to reach and kill. For cleaning plastics you will want a cleaner that fully dissolves in water before you begin cleaning with it. DO use microfiber cloth when cleaning plastic fermenters. This material works great for safely scrubbing plastic without scratching. Also, DON’T forget to remove any tags from the microfiber cloth to avoid scratching. Cleaning narrow neck carboy openings can be troublesome. Several clever homebrewers have discovered an easy cleaning method. Start by adding your cleaning solution into the thoroughly rinsed fermenter. Then stuff your microfiber towel through the carboy opening. While placing your hand over the opening, swish the microfiber and cleaning solution around the carboy vigorously. I’ve found aggressively swishing in all directions to be particularly effective in removing stubborn fermenter residue.

For stainless steel or glass fermenters, DO use powder cleaners like PBW, B-Brite, and Oxyclean. They are very effective when used with nylon scrub brushes and scrub pads.

DO sanitize your clean fermentation vessel prior to adding wort. I like to complete this task early in my brew day so I don’t forget. To avoid any outside contamination, DO be sure to cover your sanitized fermenter so they are not exposed to the open air. I like to cover my sanitized fermenter with sanitized plastic wrap while it sits for later use.

Pre-Yeast Pitch Do’s & Don’ts
DO prepare your yeast for pitching. If using dry yeast, consider rehydrating it prior to pitching. Rehydration may or may not be required depending on which dry yeast brand you are using. For example, Fermentis recently updated their pitching instructions deeming rehydration as unnecessary. Liquid yeast manufacturers have unique preparation instructions as well. For example, Wyeast uses a yeast activator that should be activated several hours before pitching. As always, check and follow the manufacturer’s instructions for yeast preparation.

Prior to pitching your yeast, DO chill your wort to the appropriate pitch temperature for the yeast. DO use a sanitized, calibrated temperature probe to accurately measure wort temperature before pitching. If you don’t have one, DO use an adhesive temperature strip on your fermentation vessel. I’ve found these strips to be very accurate for all types of fermenters. Yeast pitch temperature is critically important to yeast health and a healthy fermentation, so accurately measure before you pitch.

Fermentation Do’s & Don’ts
DO strive for tight fermentation temperature control. My early attempts to control fermentation temperature consisted of finding colder rooms in my home or basement to keep my yeast from producing off flavors due to overheating. That less than ideal temperature control method resulted in inconsistent fermentations and beer quality. DO consider investing in a small refrigerator, temperature controller and a thermowell. These three items allow you to easily control the internal wort temperature throughout fermentation. Thermowells are particularly helpful since the temperature controller probe is placed inside the fermenting wort, allowing for very accurate temperature readings.

Regardless of the temperature control method you use, DO closely monitor your fermentation. First off, it’s interesting and great fun! I’ve learned a great deal about different yeast strains and how they compare and behave. This knowledge is useful for diagnosing problems and understanding yeast characteristics. Close monitoring also allows you the opportunity to intervene when the fermentation isn’t progressing as desire. It also helps you to catch equipment malfunctions before they can ruin your beer. DON’T just pitch your yeast and forget it for a week. Even if you have a pretty automated fermentation temperature control system, DON’T “just set it and forget it”. Trust but verify.

DO take careful notes of how each fermentation progresses. Noting unique characteristics of each yeast strain not only expands your yeast knowledge but also helps you understand variability in the same yeast strain. This can help minimize your anxieties when your fermentation doesn’t go as expected. Personally, I like to note fermentation timing, including when fermentation begins, peaks and finishes. I also like to note any differing characteristics when using the same yeast for different beer styles. I find these notes useful for determining what’s normal fermentation and what’s not. The “not” might be due to yeast variability or worse, it might be an indication of the dreaded “I” word (e.g. infection).

DO consider ramping up temperatures as fermentation winds down. This practice encourages full yeast attenuation. Generally, it’s safe to begin ramping temperature after high krausen has occurred. It’s at this point in the fermentation that risks for off flavors associated is higher temperatures is significantly diminished. For what it’s worth, I prefer to ramp my temps only to the top of the ideal range the manufacturer recommends for the yeast strain I’m using. Think of ramping as a modified diacetyl rest.

DON’T use bubbling in the fermenter airlock as the only indicator that fermentation has ended. Obviously it can be an indicator of active fermentation, but the best way to determine if fermentation has concluded is to take a hydrometer reading. In fact, the experts advise taking readings over several days to verify that fermentation is stable before concluding it has ended. DO consider flushing the fermenter headspace with CO2 after taking a hydrometer reading. There are mixed opinions about whether or not this is necessary. I flush my fermenter headspace as an insurance measure to minimize oxidation risk. To my mind, if too much headspace can cause oxidation during fermentation, then opening the fermentation vessel is likely worse.

Those are my fermenting do’s and don’ts. What are yours? Please share yours by commenting below. DO stalk your next fermentation. I think you will find it educational and great fun. Cheers!


Tom Ayres @Tom__Ayres

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