Another Metallic Taste Question (Theory)

[vindee]

I have a slight metallic taste in all my beers. I have read multiple threads on this and have come up with the theory that my taste is coming from the aluminum spreader bars I installed on my immersion chiller. I usually drop it in the last 5 or 10 minutes or so of the boil before cooling.
I'm thinking maybe this is where the taste is coming from. Other than the stainless kettle and copper manifold in the mash tun I'm not using metal anywhere else in the process.
Unless this taste is a result of something other than actual metal, the aluminum could be the culprit.
Any thoughts?

 

[slym2none]

PTI, but that is an impressive bit of tubery.

 

[RM-MN]

Do you know what galvanic activity is? You have set up a great one there with dissimilar metals. All you need to do to make a battery is put it in an electrolyte, preferably acidic.

Short answer, you are probably right in blaming the aluminum spreaders for the metallic flavor. After all, wort is acidic.

 

[vindee]

PTI, but that is an impressive bit of tubery.

Tubery, I like it!

 

[vindee]

Do you know what galvanic activity is? You have set up a great one there with dissimilar metals. All you need to do to make a battery is put it in an electrolyte, preferably acidic.

Short answer, you are probably right in blaming the aluminum spreaders for the metallic flavor. After all, wort is acidic.

I see a redo in my future.
Thanks

 

[hottpeper13]

Do you know what galvanic activity is? You have set up a great one there with dissimilar metals. All you need to do to make a battery is put it in an electrolyte, preferably acidic.

Short answer, you are probably right in blaming the aluminum spreaders for the metallic flavor. After all, wort is acidic.

If this is the reason, why don't I get that taste when putting a copper chiller into an aluminium kettle?

 

[RM-MN]

If this is the reason, why don't I get that taste when putting a copper chiller into an aluminium kettle?

Perhaps because of the direction of current flow. It may take someone with better chemistry/physics background to answer that. I haven't had a chemistry class in nearly 45 years and don't remember all I learned/

 

[vindee]

If this is the reason, why don't I get that taste when putting a copper chiller into an aluminium kettle?

Interesting. Maybe it has to do with the grade of aluminum.
I used 6061 aluminum which has excellent corrosion resistant properties (which would make you think it would be less of a problem). Not sure of the grade they use for kettles. Also not even sure if it even matters.
I may just retire the immersion chiller and build a good counter flow.

 

[specharka]

Perhaps because of the direction of current flow. It may take someone with better chemistry/physics background to answer that. I haven't had a chemistry class in nearly 45 years and don't remember all I learned/

Oh boy, a chemistry lesson!

What you're referring to is galvanic corrosion, where a metal that is higher on the galvanic series corrodes instead of a connected material. In this case, aluminum is higher on the galvanic series and therefore will degrade as a response to being placed in a galvanic cell with copper.

Even though the aluminum itself is corrosion resistant, since it is placed in a galvanic cell, the corrosion occurs due to the potential across both materials (Al and Cu).

Replace those aluminum spreader bars with copper wire and you will have yourself a fine immersion chiller, sir!

 

[Yooper]

If this is the reason, why don't I get that taste when putting a copper chiller into an aluminium kettle?

It could be that the kettle has been used, and has a protective oxide layer in it. That's why you normally boil water in an aluminum kettle before use, and don't scrub off the oxide layer afterwards.