Saturday, October 4, 2008


On the whole, most of us are healthy individuals. However, we all must deal with infectious diseases or conditions from time to time. Bacterial or viral, our bodies cannot always successfully defend against the microbes that bathe our world. We all get infections. Our pets get infections. Even our computers get infections. And believe it or not, so does our beer.

Readers should already be familiar with the role of yeast in fermentation. Whether you talk about beer, wine, vinegar, bread, yogurt, cheese, buttermilk, sauerkraut or soy sauce, the process is essentially the same: microorganisms of various cultivated yeast species eat sugars and produce alcohol, carbon dioxide and a few other chemical flavoring components. We use and breed yeast to do this because the end product tastes so good.

But what is good for domesticated Saccharomyces cerevisiae is also good for hundreds if not thousands of other microbial life-forms, ranging from mold spores, bacteria or wild yeast species native to our environment. The process is similar to that of yeast, as existing sugars are consumed, but the output of these foreign bugs can contribute flavors that range from mildly sour to absolutely vile. A rare few like Salmonella can even kill you.

The dichotomy of brewing is to develop an environment that is literally an ideal world for these microorganisms to thrive and then deliberately infect it with the germ of your choice—yeast. After boiling the hops and grains during the brewing process, the resulting cooled liquor (called wort) is a sterile landscape just waiting to be populated. And it will be quickly invaded and inhabited, either by the choice of the brewer or by the chance of whatever agent can get to it first. This is why sanitation in the brewing process is paramount.

The good news in this microscopic war zone is that yeast has been bred to be very good at what it does. Whereas professional brewers have sealed industrial equipment, homebrewers can reliably and repeatedly make good beer in their kitchen or backyard. Even if a few undesirables get into the wort, yeast can usually out-compete anything else. In this environment, yeast is generally the dominant life-form.

However, yeast isn’t bulletproof. Some infections can gain a foothold and add their own flavors to the recipe. It can happen when the yeast is pitched, or when it is transferred for bottling, or even live in the plastic lines behind a commercial tap. Some states and municipalities have their own laws and procedures for maintaining brewing and beer-serving equipment, above and beyond commercial food safety regulations.

Whatever its origin, an infected beer is not too difficult to identify. In a bottle, an infection sometimes overcarbonates the beer, leading it to gush uncontrollably when opened. Flavors that infections can impart include a sour or acidic taste like vinegar (often a result of Brettanomyces, Lactobacillus or Pediococcus), a plastic taste (often referred to as "Band-Aid"), a sulfur taste like rotting eggs or matches, or vegetal components like celery, onion or asparagus. Flavors of infection tend to resemble organic substances, as opposed to other contaminants like soap or cleansers that may add more of a chemical flavor element.

The good news is that other than ruining the taste, nothing that can grow in a beer is really harmful to humans. The pH of beer and the presence of alcohol keep almost all the truly nasty microorganisms at bay. Even drinking an infected beer won’t make you sick, although the flavor and acidity may turn your stomach. If you suspect a beer is infected, always inform the manager, the retailer or even the brewer directly. Most will be happy and eager to replace it.


Yatika Dhingra said...

fantastic job on writing this...
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Reyan Loeffler said...

Very Informative and useful, Keep it up the great work. I was looking for microbial infectious diseases that become the reasons of human death, i find your post and found it informative. There is a device called Hulda Clark Zapper by ParaZapper, which kill all the microbes through electrical pulses, we should research on it.

Stacy's Helping Hand said...

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