Foam stopper question

[ChrisCorley]

I just made my first starter and for whatever reason the nice clean white foam stopper after being cleaned turned brown. It was fine until i put it in a little bleach and a some oxy clean. I noticed on a Brewing TV episode his foam stopper was way more brown. I was just curious as to how or why this happens. Thanks!

 

[worksnorth]

I'm not sure, perhaps CO2 discoloring it?

 

[pjj2ba]

Always happens. When you boil, more than just water vapor passes through the stopper. Other volatile stuff will bind to the stopper, and you get some maillard reactions (browning) occurring and presto your nice white stopper is now brown.

 

[TyTanium]

...It was fine until i put it in a little bleach.

This...whenever I put any foam in bleach it drastically changes color. Not sure why...maybe the foam is dyed white/yellow and the bleach strips the dye. Oh well, no harm done.