Ok so to go off topic. Has anyone ever experienced a sort of "dirty sock/feet odor" taste in a lager? I know that may sound weird...I don't know how to describe a taste as the way something actually smells...That could be isovalaric (sp?) acid, caused by certain bacteria in the presence of oxygen and stuff found in wort (not to sound too scientific). If its sulfur you're smelling some lager yeast strains throw that more than others. But stink feet is usually isovalaric
I have had a few commercial lagers over the years that had this distinct flavor to me but not to anyone else with me. Basically undrinkable and I have always referred to them as "feet beers". My current lager has just a very slight impression of this characteristic however I think it is something that I may just be sensitive to and not necessarily an off flavor.
Interesting. Good to know. Thanks!
"So, how does isovaleric acid get into beer? Most of the time, it’s formed when hops get old, particularly when the alpha acids degrade. I’ve discussed hop acids already in the bitterness article, so if you need a quick overview, head over there and it might clarify some things. This image (from the above-linked article) shows the basic structure of the alpha acids (on the left) and the iso-alpha acids (right) that they isomerize into during boiling in the brewing kettle (at which time they become the source of bitterness in beer). Basically, there are 3 main types of alpha acid (and the 3 corresponding iso-alpha acids) and while they have the same basic structure as each other, there are differences at the “R-group” (top right of the molecule in the images). The differences are minor, but these minor differences can be interesting and influential nonetheless. One of these 3 alpha acids (humulone) has an R-group which is called an isovaleryl group. When this alpha acid oxidizes (due to age and/or improper storage), this R-group can be removed from the molecule and becomes flavor-active, leading to the cheesy/sweatsock flavor I’m on about.
Another way isovaleric acid can get into beer is through a Brettanomyces infection. It’s not the most common source in beer, but infection by this yeast genus can produce cheesy aromas, as well as a host of other undesirable flavor-active compounds like acetic acid (vinegar), 4-ethylphenol (bandages), and 4-ethylguaiacol (smoky). Some breweries intentionally “pitch” Brett into their fermentors as they try to achieve a certain flavor profile or match a particular Belgian style, but more often than not a Brett infection is a bad thing. Brett is also used in winemaking to achieve certain flavors, but it can also be a spoilage organism here depending on the intent of the oenologist.
So limiting undesirable isovaleric acid levels in your beer comes down to using fresh and high-quality raw materials (store hops in a cool, dark environment and, if possible, oxygen-free), and maintaining sanitary brewing conditions and using plentiful and healthy yeast to limit the potential for beer spoilage."
My hops were fresh out of the sealed package so it sounds like it could be slight infection. Luckily it is barely detectable and has not worsened or ruined the batch. The strange thing is he distinctly mentions this as an aroma when I only get it in the taste. The aroma is great...