I'm allergic to bio washing powders with enzymes, and I typically wash everything at 30c so I've noticed this smell on some of my shirts over the last year or so (I'm 51)

So far to conquer it I gather the shirts with the smell together and wash them with a bio washing powder at 40c, then wash them straight away at 30c with the non bio, I've noticed a huge reduction in the smell and it doesn't irritate my skin and cause eczema - double bonus!

They say that persimmon soap is supposed to be good, or anything with tannins in, but I'll stick to my imperial leather.