Everyone wants their beer to turn out delicious and if your homebrew tastes metallic then you are probably pretty frustrated and want to know why. Since this is a fairly common off-flavor, I thought it would be a good idea to learn all the reasons you might have a metal-tasting beer.
Metallic flavors in homebrew beer are typically caused by metals contaminating the wort, alkaline brewing water, oxidation during fermentation or bottling, or improperly stored malts, hops, and other ingredients. Using the proper equipment and checking your water report are essential to avoid metallic off-flavors.
While it might seem obvious that you should just avoid potential metal contamination while brewing, the real answer isn’t quite so easy. There are many variables that you will need to control while homebrewing your beer and we’re going to take a look at each one more closely!
Why would homebrew beer taste like metal?
The simplest answer to this question is that your beer has been contaminated with metal at some point during the brewing or fermenting process. Surprise, surprise, metal makes things taste metallic!
Going further into this answer, we will find that there are many ways for your beer to come into contact with metal during your process and there are also a few less obvious things that brewers have discovered over the years that you will need to stay on top of to avoid metallic beer.
Let’s take a look at the top 7 reasons why your beer tastes like metal.
Check your metal equipment
Most brewing equipment is made out of metal because it is long-lasting, easy to clean, and stands up to the boiling process. While stainless steel is almost entirely inert and unlikely to leach any metal into your brew, the same can’t be said about aluminum, iron, or copper. Copper and, especially, iron will impart a metallic flavor into liquid quite easily. This is even more true under the circumstances that homebrewers would be using the pots for – extended boiling!
I doubt any of you out there have a giant iron or copper pot that you are using on brew day, but aluminum pots are way more common. Since they are much cheaper than stainless steel, it’s especially common to see these pots in a beginner’s kit until they make the decision to start upgrading their equipment.
The biggest issue with aluminum pots is that they should be ‘seasoned’ first before they are used as a brewing kettle. If this is your first batch of beer and you skipped this step, it’s possible that your pot has had a role to play in your metallic off-flavor – especially if your water is highly alkaline with a pH level greater than 9.
If you failed to clean your brand new aluminum kettle well, you could also be getting off-flavors from oils and other material left on the metal from the factory.
While aluminum will create a microscopic layer of aluminum oxide anytime that it is exposed to the oxygen in the air, you can increase the thickness of this layer simply by boiling water in a covered aluminum pot for a while until you see some darker color appear on the surface. If your oven is big enough, you can also ‘bake’ your kettle at 350 degrees for one hour.
Don’t clean metal equipment with bleach
Even if you are using stainless steel equipment, it’s not completely immune to corrosion and metal leaching.
Using bleach to clean stainless steel can create scratches, pits, and corrosion on the metal’s surface. These defects will open up the door for metallic contamination of your wort during the boiling phase. You should avoid using abrasive pads to clean your kettle for similar reasons.
In general, you should use a high-quality cleaner and sanitizer that is meant for stainless steel and homebrewing, in general. Good choices are Star-San or PBW.
Check your water report
If you have never read a water report for your local source then you might be surprised to find out that it’s fairly common to have metallic trace materials in tap water. This is especially true for people that use well water or live in a municipality with lots of local metal deposits.
If you get your water from the city, go online to see if they have a water report available for download. If not, call them up and ask to have one sent to you. In most cases, you should be able to get this data. If not, you will be forced to take a sample of your tap water and send it to a lab for testing. In fact, it’s usually better to do this anyway because then you will get results accurate for YOUR tap water, not just the water leaving the water treatment facility.
Those of you using well water should draw a sample and have it sent off to a lab for testing. You are looking for any heavy metals in the report.
In either case, you can avoid issues with metal in your water by installing a high-quality filtration system or switching to bottled (Purified or Reverse Osmosis) water for your brew water.
Check your home’s pipes and use cold water
I mentioned this a second ago, but just because your water company’s water report looks good doesn’t mean that your tap water is exactly the same.
Old pipes can easily contaminate water with lead and other heavy metals on their way from the water treatment plant to your home. Depending on where you live, this could be unavoidable. If that’s the case, you will need to look at getting a filtration system for your home (that’s probably a good idea anyway!).
Something to point out as well is that hot water will naturally leach more heavy metals than cold water. This is good to keep in mind if you typically get hot water out of the tap to shorten your boiling time on brew day. Not only will it absorb more metals from your pipes, but hot water also travels through your hot water heater which can further expose it to lots of other sediment and junk that has accumulated inside the tank over the years.
Be sure your water is not too alkaline
Once you have confirmed that the metal content of your water isn’t a factor, double-check the level of alkalinity as well. Alkalinity is a measure of how much carbonate and bicarbonate is in the water.
Ideally, brewing water will have an alkalinity rating of less than 50 ppm, but that is not likely without making changes to your water chemistry. Usually, you will find that your water is between 50 and 150 ppm. If it’s higher than that, you will need to think seriously about bringing that number down through chemical/mineral additions to your water.
This information is not always available on your water report, but there are cheap and easy strips or kits available to test this. You can find them online or at your local pool supply store.
Watch out for old or improperly stored malt, hops, and other ingredients
There has been a lot of anecdotal evidence that using old ingredients, especially malted extracts that have been stored in metal cans, will produce metallic flavors in your beer.
With the malt, the issue is that there will be the hydrolysis of the lipids over time which creates the flavor. In other ingredients, such as hops, it’s a little less clear why it might happen. In any event, using the freshest ingredients possible is always a good idea and it will go a long way to preventing this off-flavor and other issues as well!
Do more to prevent oxidation
It’s standard knowledge that oxidation is bad for beer after fermentation is complete (unless you are brewing a wicked barleywine!). Typically, excess oxidation will give your beer a wet cardboard smell and taste that is completely off-putting.
Less known, however, is that sometimes an early sign of oxidation issues is actually a metallic smell or taste. If you are picking up this off-flavor and it’s early on in the conditioning process then you might want to give it more time to see how it develops. It’s possible that the taste could go away over time or that it turns into more of a traditional oxidation flavor.
Here are a couple of quick ways to help prevent oxidation:
- Avoid doing a secondary fermentation – It’s easy to oxidize beer during the transfer process and there will be more headspace available in the secondary fermenter along with way less CO2 being produced, creating more opportunity for oxygen to creep into the beer.
- Be careful during bottling – Disturb the beer as little as possible during the bottling process.
- Ferment with a lid and airlock – Seems obvious, but I have to mention it.
While metallic flavors are by no means ideal, there are definitely worse off-flavors that you will have to deal with as a homebrewer. Check out all of the other ones that I’ve covered here!