Infected Beer Bottle: What to Expect

Unlike with food poisoning, which often creeps up on you hours after you have been infected, an infected beer bottle gives away plenty of signs right away. Indeed, the infection is usually obvious long before you bottle the beer. Still, you might have something lurking in the brew that hasn’t quite manifested itself, and won’t, until you open the bottle. First, let’s be clear: this situation, while not ideal and not impossible, is incredibly rare. Still, it is worth exploring for brewers seeking information on the infected beer bottle, what to expect, and how to avoid it in the future.

What Is an Infection in Beer?

An infection in beer can come in many forms – all typically from various types of bacteria. Generally, bacteria love to feed on pretty much any organic matter it can find. Thus, if you have left your beer exposed to the air without proper surveillance, if you have gone weeks without cleaning all of your equipment, or if you are bottling in un-sanitized bottles or with un-sanitized equipment, you may potentially be setting yourself up for a disaster.

The problem is that quite often the good yeast and bacteria in your brew can often fight off any bad bacteria or unwanted yeast. That safety net is what brewers have been relying on for thousands of years. Think about it.

Back in 8,000 BC, when brewers were women at home crafting a nutritious and hydrating formula for their families because they couldn’t trust the running water from the stream, they were not utilizing bleach, sodium percarbonate, or any other heavy-duty cleaner during their process.

On the contrary, they were trusting in the alcohol and fermentation process to weed out any harmful toxins. And nine times out of ten, they were right to place that trust.

Perhaps even 9.9 times out of 10.

How Can You Tell if You Have an Infected Beer Bottle?

The problem is that one time out of a hundred or a thousand that your beer stinks to high heaven.

That’s usually the first sign – stinking brew.

You know if your beer smells like sulfur or vomit or anything else off-putting, you have infected beer on your hands.

If, somehow, the beer smells fine and you go for a taste, and it tastes off, you probably have an infection on your hands. Off flavors can be a sign that you have an uninvited guest in your beer. If the beer makes you want to vomit, you definitely have an infection.

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If you open the bottle and it explodes on you, that’s another sign that something has gone horribly wrong. Of course, don’t confuse your bottle exploding from a bacterial infection with your bottle exploding from too much sugar added during bottle conditioning or from incomplete fermentation.

How to Tell the Difference?

It can be tough to distinguish. After all, by the time your bottle is exploding, it doesn’t really matter, right? You’ve got a bunch of bottles with too much carbonation.

But, if you still have some brew that you haven’t bottled, or you’re in the prevention phase for next time, the trick lies in your gravity reading.

In general, any yeast you add to your brew will consume only so much sugar and then ultimately lie dormant, waiting to be collected and reused for next time.

Wild yeast or bacteria, on the other hand, will consume far more sugar, and it will continue to consume that sugar well after you have bottled your brew.

With your yeast, you can tell when it is done when your gravity reading has lowered and stayed relatively stable for 3 days.

With wild yeast, your gravity reading will continue to drop well past what you anticipate, and then drop some more. That’s a good indication you have an infection on your hands.

Yeast Raft

Another clear sign of infection is a white film on beer you have brewed. This film is commonly referred to as a yeast raft and is the collection of pellicles on the top of your beer. It resembles woven netting across the top of your brew with tiny bumps and webbing connecting those bumps. It can also look like a classic moldy infection. Either way, it’s gross, and you don’t want to drink it.

What to Do About an Infected Beer Bottle

Unfortunately, the only thing to do about an infected beer bottle is to throw out the whole batch. Yes. It is an awful eventuality, but it is an eventuality. You cannot bring beer back from an infection.

The best thing you can do is learn from the experience and avoid this ever happening again.

How to Prevent Beer Infection in the Future

The sagest advice to all brewers is to clean, clean, and clean again.

Keeping a highly sanitized environment and one free from cracks, scratches, and leaky equipment is ideal for all brewers.

Always check your equipment for scratches and cracks as that is where bacteria most love to hang out and await the introduction of beer. It could be in a single small piece of equipment, but once it gets into a small sample of brew that goes back to the larger batch, your whole batch will be ruined.

Wear gloves, hairnets, and sanitary clothing and protective gear as well to ensure you don’t end up unwittingly contaminating your brew.

Then, clean your equipment with a sodium percarbonate solution that will ensure your equipment is sanitized.

Finally, run your bottles and their caps through the dishwasher at the highest setting with dishwasher detergent to sanitize before bottling.

Look, every brewer has dealt with an infection. You just have to chalk it up to a learning experience, call it a business loss, and move on.

To brighter and better brewing days.


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