Welcome to another post on off-flavors and how to avoid them in your homebrew!

If you haven’t yet read the previous two volumes, do yourself a favor and check them out here (Volume 1) and here (Volume 2)

Remember that in identifying off-flavors, it’s super important to start training your palate to recognize them. Otherwise, you may be brewing some nasty beers without knowing it!

Without further ado, let’s get into the messy world of (more) off-flavors!


 Off-Flavor #7: Acetic

vinegar bottlesAcetic compounds occur naturally in in beer as a by-product of yeast activity during fermentation. But in high concentrations, it can make your beer taste like vinegar, nail-polish or salt-and-vinegar potato chips. It can also appear sour to the taste, assuming that you’re not brewing a sour beer!

How to Stop it

Since this is a byproduct of fermentation, the problem usually lies with yeast health or sanitization during the cold phase of brewing. So, to stop this off-flavor, make sure that your wort is well aerated before pitching yeast, that you use non-expired, viable yeast, and that you’ve added yeast nutrients in the boil if it’s a high-gravity beer.

Also, check your sanitization procedure for the fermenter and anything else that touches cooled wort. Don’t forget those easy-to-miss items like the kettle lid, scissors used to cut open yeast packets, hydrometers and thermometers.

Off-flavor #8: Grainy

Given that beer is made from barley and other grains, it may seem strange to list “grainy” as an off-flavor. Of course, a descent, biscuit-like, malty grain taste is perfectly acceptable for most beers: Indeed, brewers creating malt-forward beers actively seek it out!

But the grainy off-flavor tastes more like whiskey or wet grain than malt. It imparts a harsh, unpleasant flavor to your beer and should be avoided.

How to Stop it

Grainy flavors are mostly a risk to all-grain brewers since they mash their base malts.

Be careful of over-sparging (either for too long or with overly hot sparge water), which could result in this off-flavor.

Measurement is key! The remedy is to carefully monitor your wort gravity as you sparge and recisculate.

Stop sparging when your runoff gravity reaches 1.008-1.010.

Off-flavor #9: Mercaptan


Mercaptan is a common off-flavor in many a homebrew because it’s a natural by-product of yeast fermentation.

At high concentrations, it tastes and smell a lot like stale vegetables, open drains, LPG gas, or onion. Hint: none of these flavors or aromas are going to help you brew award-winning beer!

How to Stop it

Mercaptan and mercaptan-like flavors are often produced because of poor yeast health. Keeping your brew in the fermenter too long may result in this off-flavor, so measure your beer for target final gravity and then bottle it.

Some types of bacteria may also produce this off-flavor, so carefully review your sanitization regime, especially during chilling and fermentation of the wort. 


Submit a Comment

Your email address will not be published. Required fields are marked *