Metallic Taste in Beer: What’s Causing It?

So, you’ve been experimenting with various brews and wondering what is causing the metallic taste in beer that can occur?

If you’ve ever bitten your lip, had a mouth wound, or licked blood off your body in the past, you have likely tasted it before – iron.

By now, most people are aware that humans have enough iron in our blood to make the taste of iron in blood detectable. Thus, when we taste anything else, metallic, it can often taste like blood to us.

But it is not necessarily blood you’re tasting. It’s metal.

Iron and other Metals

Iron and other metals are often the only thing that give off that metallic taste, and in trace amount are not detectable.

Indeed, in beer, trace amounts of iron actually foster healthy growth and stimulate strong fermentation in yeast cells.

Test Your Yeast

 

But once the metal has become detectable, it has exceeded normal rates and can cause unwanted off flavors in beer.

Is It Safe to Drink Beer that Has a Metallic Taste?

If you can taste metal in your beer, it may have reached unsafe levels and must be discarded.

The truth is that too much iron consumed alongside alcohol can lead to oxidative stress in your body and liver disease.

When too much iron gets into your intestines, your organs begin to absorb the iron and cannot get rid of it, which can cause major primary and secondary illnesses in your body.

So metallic off flavors in beer are not just unwanted, they can be dangerous.

What is interesting is that beer with normal levels of iron is actually good for people with iron deficiency precisely because beer promotes the absorption of iron.

As with most things, it is all about striking the right balance, and with the combination of alcohol and iron, that balance can be tricky.

How Iron Ions Get into Beer

Again, in general, a small amount of iron, particularly in its divalent form, is actually good for beer. It promotes yeast fermentation, it helps create foam, and it lends itself to a gentle haze in beer.

Too much can cause excessive and unwanted turbidity in addition to the dangers it can cause the human body.

Excessive iron to the point of creating a metallic taste can be caused by multiple factors.

The Yeast

Yeast and iron have an interesting relationship. Many different yeast strains are rich in iron, and yeast grows and ferments better when iron is present. Thanks to the presence of iron in most grains, including wheat, oats, and barley, yeast tends to ferment these grains just fine.

During the mashing process, when ground grains are boiled and literally “mashed in” to make a thick wort, the trace amounts of iron in the grains are released and they will serve the yeast well once it is added to the wort.

Yeast also carries iron that it does not typically release into the wort. If the levels of iron are too high in the wort, however, the iron locked into the yeast cells will “autolyse” or break out of the cell wall and dissolve into the beer.

Once the iron in the yeast and the iron from the grains are all dissolved into the wort, iron levels may get high enough that it is detectable to the palate.

Water

Water also naturally contains iron, but again, at normal levels, even with the iron from the grains, the iron levels should remain low enough to be both helpful for fermentation and harmless to humans.

It would still serve brewers to check the iron levels in their water, however, particularly if the source of the water is a well or especially hard water.

Hard water can bring the overall pH of the wort up as well, which can cause an increase in oxidation and release the iron from the yeast cell walls, once again driving up the overall iron levels to detectable and higher levels.

Thus, brewers should check both iron levels and the pH of the water used in brewing.

The Container

Finally, and most commonly, excess iron can come from the container in which the wort is mashed. Most brewers today will use the classic copper kettle that is coated with a protective film so as not to leach any minerals into the brew.

But inexpensive, old, or damaged metal containers can often leak iron into the wort and drive up iron levels across the board.

The Complex of Iron in Beer

Ultimately, iron levels are most often driven up not by a single source but by a catalyst of sorts which increases iron levels exponentially.

At every stage of brewing after the mash-in, so the boil, sparging, the cool down, fermentation, and even racking and secondary fermentation, the iron ions from all the various sources have the potential to mesh with other substances in the wort like enzymes and amino acids and create iron complexes, which are what become harmful to humans in large amounts.

Thus, it is important to be aware of and control for balanced levels of iron at every potential source.

How to Control for Iron in Beer

The easiest way to control for iron in beer is to test your water and be mindful of your metal containers.

You shouldn’t have a problem with your grain or your yeast as long as your water is not too high in iron and your metal containers are not corroded or cracked, causing them to leach iron.

If you do find that your water is too high in iron, you will likely need to switch water sources.

And if your containers are leaching iron, it is a good idea to invest in copper kettles designed specifically for brewing.

Once you cut out the source of extra iron, you should resolve any metallic taste in your beer.

Cheers!

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Sources:

  1. https://beersmith.com/blog/2016/10/14/metallic-flavors-in-beer-off-flavors-in-homebrewing/
  2. https://www.micetcraft.com/guide-to-beer-off-flavors-metallic/
  3. https://www.recoveryranch.com/addiction-blog/hemochromatosis-and-alcohol/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166273/
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