How do you detect contamination?

[Davevjordon]

Haven't had a batch go bad yet "fingers crossed". Now fermenting I think batch numbers 6&7. I worry about each batch, and feel like I don't really know for sure until I pull the tap handle and take a swig. Can you tell if a batch got contaminated before that point? By visual or smell? Or taste the beer before kegging? What would you see / smell / taste?

 

[dawn_kiebawls]

I'm a fellow rookie as well, with fewer batches under my belt than you in fact. Take this for what its worth since I have no first hand experience with an infection, however my own paranoia has caused this to be a heavily searched topic for me. It is my understanding, *somebody correct me if I'm wrong* that an infection will take hold pretty rapidly and show up in the form of mold (not a pellicle) in the fermenter. As far as taste differences I've read it ranges anywhere from a putrid 'spoiled' taste to some sort of a 'sour'. There are several quality threads on here going into further detail.

An infection is not a 'death sentence' for the beer in every case, as the 'mold' link will back up. I hope this was some sort of help to you! Cheers

 

[mongoose33]

Just finished batch #36.

I always taste the beer when I'm checking gravity to see if it's done fermenting, and when it is racked into the keg. I've never had one be bad at that point. In fact, they usually are pretty tasty, more than I would expect given they're warm and uncarbonated.

I did have a porter go squirrelly on me but that was weeks after kegging. It was a gusher that still tasted ok.

I agree with Dawn above; I think you'd likely see something on the surface of the fermenting/fermented beer to indicate a problem.

In the end, cleanliness and sanitation is not only your friend, it's an absolutely necessary ally. I read someplace that new homebrewers tend to get an infection, if they get one, around their 10th batch. The reasoning is that poor cleaning practices allow stuff to build up and by that 10th batch (or so), there are places for bacteria to hide from sanitation. And then infection.

 

[Davevjordon]

Thanks, Mongoose. I'll make sure I keep a tight reign on my cleaning and sanitation practices as I near batch #10.

 

[Davevjordon]

I believe next month will mark 2 years that I’ve been homebrewing. Never had a batch that I had to toss, and I STILL worry about every single one!

 

[RPh_Guy]

Potential signs of a contamination:

- Moldy patches on the surface.
- A pellicle (not to be confused with mold). Usually a white powdery film.
- Unexpected flavors or aromas, especially phenolic.
- Unexpected texture. (i.e. "ropy")
- Overattenuation or gushing.
- Slow or stalled fermentation.

an infection will take hold pretty rapidly

No, a contamination may take days, weeks, or months to be detectable.

show up in the form of mold (not a pellicle) in the fermenter.

- Mold and pellicle are different things.
- Mold growth indicates a mold contamination. Pellicles are formed by yeast and/or bacteria.
- Contaminations do not always show visual signs.

. As far as taste differences I've read it ranges anywhere from a putrid 'spoiled' taste to some sort of a 'sour'.

Yes, the taste ranges. It can be almost anything; wild yeast and bacteria can produce a full spectrum of flavors. Fruity, spicy, clove, honey, smokey, sour, vinegar, buttery, green apple, rotten eggs, sewage, etc. etc. etc.
The key is that it's unexpected.

An infection is not a 'death sentence' for the beer in every case, as the 'mold' link will back up.

Moldy beer should be dumped. Mold is allergenic and can produce carcinogens and toxins.
Other contaminations (yeast/bacterial) you'd need to judge on a case-by-case basis whether there are any flavors present (there may not be any) and whether they're acceptable to you.
If there's a pellicle, don't panic. It might be perfectly fine.

Cheers.
Edit: wow, old thread. Glad you've been contamination free!

 

[grampamark]

I just ordered a "Super Contamination Detector" from the Acme Corp. I figured, if they’re good enough for the coyote...

 

[Jag75]

@RPh_Guy - what's is Ropy ? Like stringy things?

I always worry about infections. I run my Grainfather for 20 - 30 min with pbw , then just hot water for rinse . That's through the return arm and the cfc. My fermenters I try not to scratch but scrub . Those little nooks and crannies are what scare me , like the temp probe port and the ball valve area.

 

[brownni5]

@RPh_Guy - what's is Ropy ? Like stringy things?

I always worry about infections. I run my Grainfather for 20 - 30 min with pbw , then just hot water for rinse . That's through the return arm and the cfc. My fermenters I try not to scratch but scrub . Those little nooks and crannies are what scare me , like the temp probe port and the ball valve area.

Basically, yeah, stringy. The beer becomes very viscous - caused by pediococcus. A quick Google search will show/tell you more than you ever wanted to know.

Too much "worrying." Basic sanitation will take care of everything. Or, embrace the funk!

 

[Qhrumphf]

pH is another good indication. You can often pick up a contaminant there before any other signs show. Although each yeast (and subsequent generation of it) will impact things differently, so it's a matter of experience to know what is and isn't normal.

I read pH every time I check the gravity.