New to the forum. I feel privileged. Still just a K&K brewer but looking at partials soon.
I know this is digging up an old post but I was just wondering if any of you found an answer to why a brew would lose bitterness as it ferments?
I found this on the Coopers website. Not sure if it helps.
"Much of the bitterness is made up of surface active compounds - this is why the foam of a beer is more bitter than the beer itself. Also the main reason a more bitter beer displays better head retention.
Surface active compounds attach themselves to the krausen (foam) and become trapped in the crusty ring on the wall of the FV. Also adhere to the yeast falling out of suspension.
Some bitter compounds fall out of suspension as the pH of the brew drops to a certain level - this is known as their "isoelectric point"."]
As for the bitterness attaching itself to the krausen I can vouch for that personally. Try running a fingernail through the scum ring and touching it to your tongue and you'll see what I mean. I wouldn't reccomend this with an IPA or big stout though