I skim the foam prior to adding my first hop additon (in the boil) only because I have noticed that I end up with less trub/cold break in the bottom of the kettle when I am done brewing.
I usually add hops as a first wort charge which makes it counterproductive to skim the foam. When I do not first wort hop, I have been known to skim, but this is mostly because some really good brewers I know skim, not because I have seen any difference.
For what it’s worth (if it’s worth anything) I don’t and have never skimmed off the hot break foam. It typically falls back into the wort and to me it’s easier to deal with the trub than try to skim.
I read way back in the early days of this hobby that the foam contributed to stability of the head in the glass. That’s probably a myth too. ;D
Never seemed worth it to me. A spray bottle of water will make the foam fall if it gets out of hand.
I skim because it’s what I do with chicken stock. That doesn’t mean it makes a difference with beer. It’s just a cooking habit. For that matter, I’m not sure it matters with chicken stock. In both cases, I suspect I do it more as “something to do.” At least hovering over the stove means fewer boil-overs.
“Hot Break and Skimming – The first think you want to watch for as you are heating your pot is the hot break, where a nice foam of protein often forms on the top of the pot. Ideally you want a strong hot break, which means you should run your stove on high until it starts to form. The hot break, which often foams up and causes boil-over, is primarily precipitated proteins from the grains which coagulate on the top of the pot. Some people take to skimming the “hot break” from the top of the pot to cut down on the protein remaining in the beer, and I think this is a good idea if you are brewing a light beer. Skimming also reduces the chance of boil-over.”
I skim…add add 1/2 a whirlfloc tablet and extra Irish moss and try to keep as much trub out of the fermenter as possible. I mostly keg, but I bottle some and since I’ve started this, the trub in the bottles is minimal and tight and the second pour from a 22 oz bottle is not all f!@#%&d up…