When we brew beer we must boil it for at least 60 minutes before we chill it and pitch yeast and during the boiling phase, the foam will always form at the top of the wort.
The foam is formed because the proteins from the grains are pushed at the top during high temperatures and it’s completely normal and to be expected.
The foam can be inconvenient for some, so the question is should we remove the foam during boiling or should we let it be?
You can remove the foam without worrying it will impact the beer as long as you haven’t added hops prior to it, but it’s not necessary as the foamy surface is a normal part of brewing and it will later dissolve within the fermenter.
Not all grains contain the same amount of proteins, so while every single grain mix we use for brewing beer will create foam to some extent, wheat beers will produce the most because wheat contains a large amount of protein.
Remove foam only prior to adding hops
If you decide to remove the foam, don’t do it once you already added hops into a boiling wort. When hops are added they’ll immediately start to release alpha acids and which will form at the top. If you scrap the foam you’ll also scrape off the precious hops and deteriorate their effect whether you are bittering, flavoring, or just adding a notch of aroma to the beer by the end of the boil.
That said, this applies to BIAB and every other brewing method, and in case you are not putting the hops in muslin bags first and instead throw the hops straight in, then it’s more than obvious how you could easily remove the fresh hop particles from the top and in other words, de-hop your precious future beer.
So, in either case, if the hops are in, don’t scrape any foam unless you notice a wine fly or a piece of husk floating.
Remove foam to reduce the risk of overflow
Removing the foam during boiling is a smart choice if you have serious problems with overflow. This is not an issue for every homebrewer because lots of it depends on the quality of the brewing kettle, its size, temperature control, and the amount of wort you are brewing.
However, if your kettle is full to the top so you can maximize the use of a brewing kettle (I always brew 5 gallons and my kettle can barely take over 5 gallons) you may experience overflow.
In my case, I don’t remove the foam and I rarely experience overflow even though my kettle is always full to the top. Truth be told, although rarely, I still from time to time experience minimal overflow but it’s minimal and nothing is lost. I also quickly clean it from the stove to minimize the mess. Seriously, reacting quickly before the stains dry is a big help because just like with any stain in homebrewing it only gets harder to clean it the longer you wait.
Does removing foam affect head retention?
This is an interesting question as some brewers believe that proteins that form foam during boiling don’t play a role in the later forming of head retention so you could remove it without worrying that it will impact the beer in any way.
However, there are also brewers who claim that those proteins are essential for head formation and retention.
The fact that proteins play a big role in head retention is absolutely true and for such reason wheat beers are traditionally always extra foamy with solid head retention. It’s good advice to include 3-5% of wheat grain in any recipe as a trick to increasing head retention.
In my opinion, it shouldn’t matter if you remove the foam during boiling because you are not removing all proteins from the wort by scrapping the surface once or twice to make the boiling process more convenient.
There will still be plenty of proteins in the beer that will form a nice head that will last for a long time if the recipe is correct.
If you are looking to improve the head retention on your beer it’s not that hard and it only requires a few tweaks in a recipe or in a brewing method.
Will the removal of the foam impact beer clarity?
More yeast and proteins that come from sediment (that’s where the proteins from foam turn into later) are important for hazy beer styles like hazy IPAs or hefeweizen bavarian beers. Introducing extra yeast character and protein from the grain is the mandatory factor that makes a great hefeweizen.
In such a wheat beer style it’s expected for it to have a strong yeast flavor and muddy appearance and if you want to recreate such a style consider not interfering with foaming during boiling for that little extra gain.
However, for other wheat beers like crystal wheat beers or literally any other style which is enjoyed clearly scrapping the foam off during boiling can help achieve the clarity sooner, so it may play a small role in clarifying in later stages.
Although it’s logical that fewer protein particles will form less sediment in later stages, the difference isn’t huge and there are better clarifying methods for your beer you can use. After all, those other clarifying methods will still be mandatory because some foam at the top during boiling won’t make a significant difference.
In conclusion, I wouldn’t scrap off the foam during boiling just because I’d expect a clearer beer.