Metallic off flavors can occur in both commercial and home brewed beers. They are almost always considered an off-flavor or flaw in the beer to be avoided.
Metallic off flavors can vary in taste and aroma. Copper, tin or iron flavors are common and even blood-like flavors may be present.
The Root Cause of Metallic Off Flavor in Beer
Not surprisingly the cause of metalic off flavors is the presence of actual metal in the beer. The most common is iron which produces blood-like or steel flavors, though you can lose flavor stability if you get a large amount of copper or other metals into your beer.
Inexpensive, porcelain coated steel pots are a common cause. All it takes is a small chip of the porcelain to leave exposed steel which can rust and leach into your beer. Exposed (unseasoned) copper, the chrome chipped from faucets and other metallic equipment can also create off flavors. Most modern commercial brewing equipment that appears to be made form copper or iron is actually stainless steel with copper cladding for visual appeal.
Stainless steel is probably the best insurance against metallic off flavors, though some extremely cheap low carbon stainless steels may not be so “stainless.” Aluminum is also acceptable if it has been properly “seasoned” so that a oxidized patina has formed over the metal.
Using the wrong cleaning agent on metals can create off flavors. For example bleach should not be left in contact with stainless steel for an extended period or it will corrode. Make sure the cleaning agent you are using is safe for the metal you are working with.
It is also possible to get metal directly from your water source. Some well waters, in particular, can have high iron or other metallic ion content which can ruin your beer. If in doubt, have your water tested by a reputable lab.
Those are a few tips on avoiding off flavors in your finished beer. Thanks for joining me on the BeerSmith Home Brewing Blog. You can grab a trial version of BeerSmith from BeerSmith.com. Be sure to sign up for my newsletter or my podcast for more great tips on homebrewing.
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