Biab question with a twist

Hi all,

Last year I made a biab IPA in my aluminum brewpot. I posted some questions after drinking some last year cause it was quite dark and tasted very malty/bitter. I kinda liked the color. It was very clear and a nice deep red hue.

I made the same recipe a few weeks ago but normal mash in my cooler,etc,etc. This batch is way lighter in color and not any where near the same flavor or maltyness.

I’m wondering if perhaps mashing in aluminum pot via biab may have pulled color and or some off flavors from the black stuff on the inside of the pot. Anyone have a similar experience or have a theory?

Grain bill was the same for both batches, same yeast, mostly same hops but not identical.

Really doubt it. That black colored lining is a protective oxidation which prevents aluminum salts from getting into your wort. It won’t leach into your wort. Try boiling plain water in it and you’ll see.
So, it’s more likely differences in the water profile which lead to more or less color being extracted, or differences in mash temperatures giving a different fermentable/nonfermentable profile, or especially differences in the boiling time/intensity leading to more or less melanoidins.
It’ll be interesting to see how much different it’s aroma and flavor will be.
I’m over two years into my brewing career and so am still experimenting with different styles. But I have done several different brews 3 times and one 4 times. They have all been a little different with each.