This week I’m going to continue my discussion of common homebrew flaws. Last week I discussed Grassy, Lightstruck, and Metallic. This week I’ll touch on Musty, Oxidized, and Phenolic. I’ll cover general recognition, causes, fixes, and preventative measures for each.

Musty/Moldy

This is a pretty simple one to recognize. We’ve all smelled musty clothing or towels, wet basements, and other just funky smelling places (maybe your favorite hole in the wall?). Well if your beer has these aromas or the flavor of moldy stale bread you likely have this flaw. Typically this is caused by an infection due to less than ideal sanitization practices or a slipped airlock in a damp location like a fridge or basement. Ever pop the airlock when you forgot a blow off tube and go to long without noticing/replacing? This could be the end result of that. Most of us have been there. The moral of that story is to always use a blow off tube with a properly placed/sanitized bucket or have plenty of head space. On the sanitization side, be sure to step up your sanitization and use a no rinse sanitizer (like Starsan) with the appropriate dilution. Soak or spray your equipment and let them sit for as long as recommended.

If you already have this issue you may not be completely out of luck. If you caught it early enough and you are still in the fermentor you can try to scoop the mold off of the top of the beer. If it didn’t get down into the beer you should be ok at least for a while. I recommend bottling asap (assuming you are at F.G.), chilling the beer down to slow any future growth, and drinking it asap.

If you caught this after bottling or kegging and it is now showing these signs, keep it as cool as possible and drink it fast. If it is too far gone, dump it - there is no decent resolution to recover the beer and it isn’t worth any more of your time.

Oxidized

We’ve probably all had an oxidized beer at one point or another. You may not have known it, but it happens with time and conditions. If a beer gets too hot it will almost certainly happen. Additionally, bottling or kegging practices can lead to exposure to oxygen which starts this issue. You will recognize this flaw by the smell and flavor of paper, wet cardboard, or even sherry notes. This is the typical progression too. Anytime a beer is exposed to oxygen post-fermentation it is at risk of becoming oxidized. Of course it is nearly impossible to keep all oxygen out therefore it is important to keep the beer cold to slow oxygenation. If you really want to experience this flaw, uncap a bottle and like a good whiff of oxygen into the bottle. Recap the bottle and store it in a hot dark place for a week. Reopen and enjoy....???

Once the beer is oxidized there is really nothing you can do to fix it. Drink it before it gets worse. Of course if you are making an Old Ale or even and aged Barleywine or Russian Imperial Stout these notes can be appropriate in moderation. To prevent this ensure you keep the beer away from oxygen if at all possible. Be sure to flush and blow off your kegs several times with CO2 before kegging. If you will be storing the beer for a while, try oxygen absorbing caps on your bottles. If you can flush bottling buckets or bottles with CO2 give that a try. This is a great feature of the beer gun, the ability to flush bottles with CO2. When I use a bottling bucket I use a CO2 cartridge and bike tire inflator to flush the bottom of the bucket and make a nice layer on the bottom to protect the beer. Think all of this is overkill? Just remember this is an extremely common flaw in home and commercial brew. Better safe than sorry on this one.

Phenolic

This is another tricky one like Easters. These are ok in many styles of beer if they are the right type and quantity. Think of a nice German Hefe, it is supposed to have that note of Clove in it. Lots of Belgian beers have a spicy/peppery note. These are perfectly acceptable in some styles. If you have these acceptable phenols in the wrong style they will also be unwanted. You don’t want a clove note in a light american lager for example. These bad boys can take a turn for the worse too. They can present themselves as plastic, band-aid, or medicinal like chloraseptic. If you find yourself with these negative phenolics you probably have either a wild yeast infection, seriously stressed yeast, leaching from PVC or chlorine coming through in your water.

Once you have these, they may fade a little with time which may take a beer from undrinkable to drinkable, but in general you will have a lost soul. If it is bad enough just get rid of it if it doesn’t improve with time. To prevent these types of phenolics first ensure you are following the proper sanitization practices described above and be extra critical in ensuring everything you use is cleaned first then sanitized. Beyond that ensure you have a nice healthy pitch of yeast, preferably using a yeast starter and oxygenated wort with a well controlled fermentation temperature. Next, dechlorinate your water. Either use store bought RO, Distilled, or spring water that is not chlorinated or toss a campden tablet into your brewing water before you begin brewing. These tablets neutralize the chlorine in the water and make it harmless to your flavor. Lastly, ensure you’ve made the right yeast selection for the beer you are trying to make. Read up of the yeast before you select it and ensure you understand the phenolics it creates before you place it in a beer. As I mentioned in a previous article you can leach phenols from PVC including your better bottles. Do not let hot water or wort come in contact with any plastics above the recommended temperature for the plastic or you risk some nasty phenols.

Next week I’ll continue discussing more flaws and their prevention/correction.