I left my stove un-attended for 8 weeks and when I got back to using it, I noticed mould on one of the stove's knobs. I sprayed some white vinegar, let it sit for 5 minutes and wiped it off. Sadly, it has turned the knob pink in color.
What causes aluminium to turn pink in color and how can I restore this knob to its original aluminum color ? I live in a very humid coastal city in Australia if that helps. Here's a picture of the pink knob :