This is translated “I put on an air of interest.” which, in English, means that you pretended to be interested, but it was fake, and you weren’t actually interested. Is this what the German sentence means?
I don’t know this word well, I have only heard it used to describe aromas, like if you’re drinking tea and there is a hint of a certain aroma in it but it’s not very strong, or like if you catch a whiff of a smell (like a brief, fleeting smell) when passing something.
To me it seems like the German sentence here would mean that the person was genuinely, but only very slightly interested. If this is the case then the current translation is wrong. But I don’t actually know about the idiomatic usage in a sentence like this so if a native speaker could clarify I would be grateful!