Metallic taste and my brew pot

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iloman

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I've completed four extract brews now, and I've noticed the last two have a metallic aftertaste to them (the latest being stronger than the previous). After doing some research I believe this may be related to my brew pot. Since I'm brewing on electric there's a small ring at the very bottom of the pot that looks like some of the malt extract, or the wort itself, burned just a enough to make an impression of the coils. When that happened the pot got a good scrubbing. My fear is it got scrubbed too much and may be causing the metallic taste.

I've read that some people do an acid bath by putting a double strength solution of Star San into the pot and letting it sit for 60 minutes. My issue is I have no clue if this pot is aluminum or stainless steel (I don't cook much and there aren't any markings at all on the thing to tell me one way or the other). Is an acid bath safe to do on either aluminum or stainless steel? If so I think it would be an easy step to help eliminate it as the possible cause.

Thanks,
Jason

ps. I also read water could be the issue, and I've been using bottled spring water. I plan on checking the next batch of water bottles to make sure iron isn't listed in the ingredients.
 
Some good info here:
http://www.howtobrew.com/appendices/appendixB.html
http://www.howtobrew.com/section4/chapter21-2.html

From above:

Metallic
Metallic flavors are usually caused by unprotected metals dissolving into the wort but can also be caused by the hydrolysis of lipids in poorly stored malts. Iron and aluminum can cause metallic flavors leaching into the wort during the boil. The small amount could be considered to be nutritional if it weren't for the bad taste. Nicks and cracks ceramic coated steel pots are a common cause as are high iron levels in well water. Stainless steel pots will not contribute any metallic flavors. Aluminum pots usually won't cause metallic flavors unless the brewing water is alkaline with a pH level greater than 9. Shiny new aluminum pots will sometimes turn black when boiling water due to chlorine and carbonates in the water.

The protective (grayish) oxides of aluminum can be enhanced by heating the clean pot in a dry oven at 250°F for about 6 hours.
 
If you want to determine the metal your pot is made from, here are a few hints.

Stainless steel is much harder than aluminum. If it's aluminum, you should be able to easily put a deep scratch in the pot (try an unsuspecting spot on the outside) with a butterknife.

If you have stainless steel utensils or another pot for which you can confirm the metal, compare colors. Stainless steel is a bit more blue with a hint of gold or yellow coloring. Aluminum is more white/gray.

Also, aluminum is much lighter in weight than stainless, but I don't have a good way of describing exactly how heavy your pot should feel one way or the other.
 
iloman said:
...My issue is I have no clue if this pot is aluminum or stainless steel ...
You can try a magnet, it will not stick to aluminum but probably will on a typical stainless one
 
I Bought A Stainless Steel Pot From Sports Authority And A Magnet Wont Stick To It....sorry For The Caps
 
Are you trying a larger heavier one, there might not be enough magnetic properties to hold its weight. Try one of the thin refrigerator ones, they are easier to see if there is some attraction going on.
 
Yuri_Rage said:
Because of the high nickel content, stainless typically doesn't have very magnetic properties.
Correct but aluminum has none so if a fridge magnet slightly attracts then would be SS and not aluminum. It is a quick easy non destructive test.

I tried a few SS pots and pans and although it may not have "stuck" to it, most had at least a slight attraction. And oddly enough more at the top then the bottom.
 
whodwho said:
Correct but aluminum has none so if a fridge magnet slightly attracts then would be SS and not aluminum. It is a quick easy non destructive test.

I tried a few SS pots and pans and although it may not have "stuck" to it, most had at least a slight attraction. And oddly enough more at the top then the bottom.
I just took a couple of small rare earth magnets (the kind you can barely pull apart) and tried intently to feel an attraction against several pieces of stainless brew equipment from several manufacturers. I felt no magnetic attraction whatsoever. Some stainless alloys (303/304) may slightly retain the ferrous/magnetic properties of their parent steel, but high nickel/chrome/manganese alloys (316) will lose those properties completely.

EDIT: I just proved this with an accurate (+/- 0.1 oz) digital scale and some welding rod. I put 309 rod on the scale and waved the magnet above it. The reading got lighter by 0.2 oz, proving magnetic attraction. With 316 rod, there was no change in the scale reading. FYI, 309 is the most ferrous of the common stainless alloys and can be used to join mild steel and stainless.

FURTHER EDIT: whodwho, not trying to prove you wrong (as you are partially correct!), just amplifying the information you gave. The magnet test is definitive if it shows some attraction, but inconclusive if it shows none.
 
Geez, I feel bad that I kinda hijacked your thread with the metallurgy discussion. To get back to the point, the Star San bath should do the trick whether it's stainless or aluminum. I'm guessing that it's an aluminum pot, as stainless shouldn't leave a metallic flavor like that, even after being scrubbed bare.
 
I had a "wrong metalurgy" stainless false bottom that put some metalic taste into a couple batchs. Or maybe soaking it in chlorine (a no-no for stainless) did something to it's surface . It has rusted since I stopped using it...
 
Yuri_Rage said:
Geez, I feel bad that I kinda hijacked your thread with the metallurgy discussion. To get back to the point, the Star San bath should do the trick whether it's stainless or aluminum. I'm guessing that it's an aluminum pot, as stainless shouldn't leave a metallic flavor like that, even after being scrubbed bare.
No worries on where the thread went, I was getting a kick out of it and even chuckled as I told the wife about it.

So based on everyone's feedback - this thing is aluminum. I'm going to go for the Star San bath instead of putting it in the oven for 6 hours since I don't really want to run my electric oven for 6 hours. Between the electric $$$ and having to keep my 20 month old away from the oven/kitchen for that long the chemical solution is definitly the easiest to try.

I'm kicking around the idea of an altbier for the next batch, or a california common, and hopefully whatever I go with won't have that flavor lingering around.

Jason
 
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