Friday, December 12, 2014

How Do I Know If My Beer Is Infected?

One of the most common questions we get at the shop is "How do I know if my beer is infected?"

Large viscous clear bubbles or large bubbles under a grey "baby powder like" film are a sure sign you may have an undesired bacteria or yeast inyour beer. Healthy beer should have no grey "skin" or film on top, and generally only small, compact bubbles or small "rafts" of small bubbles with some protein or hop matter on the surface.

Here are our two different brown ale batches from the same brew day: The darker beer is a sour brown ale, a beer intentionally inoculated with multiple "wild yeast" and bacteria strains. the lighter, brown creamy looking beer is a standard, healthy fermentation on the same wort with "regular yeast" only. both are the same age, and same base beer, just different yeasts, and in this case bacteria.

The sour brown ale will continue to form a large "pellicule" on the surface, which will become thicker and more prominent with time. Eventually, the pellicule may break apart and fall to the bottom.

A pellicule may form rapidly, or may take weeks or even months to show. not all infections will show such obvious signs. many infections go un-noticed until tasting or bottling. infected bottles may become over carbonated, or even explode! infected beer may have a number of odd flavors such as: tin, metallic, barn yard, green apples, sour cherries, wet leather, pineapple and horse sweat. There are many other flavors that may occur, as this is not an all-inclusive list.

Most brewers view wild yeast (such as brettanomyces) or ANY bacteria growth in their beer to be negative and unwanted. There are, however, many beers which are prized for their flavor profile which is driven by fermentation by organisims other than Sacchromyces yeast. Proper sanitation is the ONLY way to prevent an unwanted infection by competing organisms. ANYTHING that touches your un-fermented wort after the boil may carry unwanted "life" unless properly sanitized. Sanitation is the MOST IMPORTANT aspect of quality craft brewing!

Hope this answers some burning questions!

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