Contamination in Home-Brewed Beer: How you can tell your beer is wrecked

Sunday, January 21, 2024

The art of brewing beer at home is both a science and a craft, requiring a keen understanding of the process and the potential pitfalls. One such pitfall is contamination, which can ruin a batch of beer, wasting time, effort, and resources. Detecting contamination in home-brewed beer is crucial to ensure a successful brew.

The process of identifying a tainted batch often begins with a simple yet effective method:

Tasting it.

Yep, slurp that wort down.

Zesty eh?

guide to infected beer brewing issues

The Telltale Taste Test

The taste test is a straightforward approach to determining if your beer is infected. When a beer is contaminated, it often acquires an offensive taste, which can range from slightly off to repulsively foul. This unpleasant taste is a clear indicator that something has gone awry in the brewing process.

If you have ignored the obvious and actually bottled infected beer two things may happen. First up, when you open the beer bottle, it will gush like Little Faithfull - the foam with rocket out - usually due to a rogue yeast taking over your wort.

The second is that your beer bottles may start to explode due to CO2 build up - the CO2 has to go somewhere - and trust me, from personal experience it will leave glass shards everywhere. In fact, the explosion can also set off other bottles to explode.

Symptoms of Contaminated Beer

A variety of symptoms can signal that your beer is contaminated. These include:

  1. Unpleasant Taste: If your beer tastes exceptionally bad, akin to the most disagreeable thing you've ever consumed, it's likely tainted.
  2. Nausea-Inducing Sensation: A beer that makes you feel nauseous upon tasting is a strong indication of contamination.
  3. Sulfuric Aroma: A beer with a rotten egg smell, reminiscent of sulfur, suggests an infection. This is often due to unwanted bacterial activity.
  4. Over-Carbonation: An overly fizzy beer, which may foam excessively upon opening, can be a sign of over-carbonation caused by rogue yeast or bacteria. This should not be confused with the effects of excessive sugar added during the priming stage, which can also cause over-carbonation but is not a sign of contamination.
beer infection how to tell

Visual Inspection: A Crucial Step

Before bottling your beer, conducting a visual inspection is essential. Look for signs like a 'pellicle' or a yeast raft forming on the surface of the wort. A pellicle is a biofilm created by certain types of bacteria and wild yeast strains and is a definitive sign of contamination.

The Importance of Cleanliness and Sanitization

Cleanliness and sanitization are the cornerstones of successful brewing. The primary cause of contamination is often a lack of cleanliness. Every piece of brewing equipment, from fermenters to mash tuns, must be thoroughly cleaned and sanitized. Using hot to boiling water and a reliable cleaning agent, like Powdered Brewery Wash, is advisable. Following cleaning, sanitization is crucial. Sodium percarbonate is a highly effective sanitizer and is readily available.

When it comes to bottling or kegging, the same rigorous cleaning and sanitizing procedures should be followed. For bottles, a useful technique is to rinse them thoroughly and then run them through a dishwasher on the hottest setting to eliminate any residual microbes. On bottling day, a quick soak in a sanitizing solution ensures the bottles are ready for use.

Contamination in Home-Brewed Beer:

Addressing the Rotten Egg Smell Mystery

The rotten egg aroma, while often a sign of contamination, is not always indicative of a spoiled batch. Certain yeast strains naturally produce this scent, and bottle-conditioned beers may exhibit this aroma if opened too early. The smell usually fades as the yeast continues its activity. In regions with high sulfate water content, such as Burton-on-Trent, England, this scent is characteristic and known as the 'Burton Snatch'. However, if the rotten egg aroma is accompanied by an unpleasant taste, it likely signifies that bacteria have contaminated the beer.

For wine or cider makers, the natural yeasts present in fruits can cause similar issues. Many cider makers use Campden tablets to neutralize wild yeast, opting instead for yeast strains that align with their desired flavor profile.

In summary, detecting contamination in home-brewed beer involves a combination of taste testing, visual inspection, and understanding the common signs of infection. Maintaining cleanliness and thorough sanitization throughout the brewing process is paramount to prevent contamination and ensure a high-quality brew.

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