Las contaminaciones que no querrás cuando elaboras cerveza

We like beer, and we like it to be in perfect condition. However, sometimes our drink develops unpleasant flavors and aromas. In this case, the beer is most likely contaminated. Pay attention to the following list of contaminants that, if you’re not careful, can ruin it.

• Isoamyl acetate: in certain amounts it is acceptable, as it gives the typical banana flavor of wheat beers. However, at high concentrations it can be unpleasant.
• Acetaldehyde: this by-product of alcohol formation will give the beer a flavor somewhere between herbal and vinegary.
• Acetic acid: gives the beer a vinegary flavor. The most likely cause is bacterial contamination. It’s advisable to disinfect all the equipment if it’s detected.
• Butyric acid: this contamination is reminiscent of cheese or rancid butter. The main cause is an excess of starch that has not been converted into fermentable sugar.
• Caprylic acid: we perceive soapy flavors that will make our beer an unpleasant liquid.
• Isovaleric acid: we perceive a cheese- and sweat-like aroma. We must check that the hops are fresh and have not begun to oxidize.
• Lactic acid: a sour, yogurt-like flavor invades our beer. In this case, it is most likely a bacterial contamination.
• Diacetyl: a weak fermentation causes this compound to remain in the beer. To avoid a buttery flavor, it’s important to carry out a well‑oxygenated fermentation.
• DMS: most lagers contain DMS (dimethyl sulfide), but in excess it produces a stale flavor reminiscent of garlic. Simply chill the wort quickly and keep the kettle uncovered during the boil to avoid this off‑flavor.
• Ethanol and higher alcohols: we feel warmth in the mouth and throat. These types of alcohols are undesirable because they are the main cause of hangovers.
• Indole: this compound causes a fecal aroma in beer and can lead to stomach problems. We must therefore watch for possible tank infections and sanitize them.
• Mercaptan: stands out for its sulfur and rotten egg smell. It is usually caused by the degradation of hop alpha acids when exposed to light. For this reason, it’s best to store bottles in the dark.
• Metallic: a metallic taste in beer is never pleasant. To avoid it, it’s best to store it in stainless steel containers and control the metal content of the water.
• Moldy: most likely our beer is oxidized or has been stored for a long time in poor conditions.
• Papery flavor: usually appears due to beer oxidation and is reminiscent of the smell of wet paper.
• Overcarbonation: this may be the most common form of contamination in beer and results in excess gas. It occurs when too much sugar is added during conditioning.

Now you know the main contaminations that affect craft beer. Some originate during brewing, while others occur during dispensing (cleaning), but all of them can ruin it. From now on you’ll be able to detect them easily.