Multiple late Boil hot breaks/Aggressive foaming sessions

[FatherSonBrew]

Occasionally during a brewing boil task I will see multiple very spontaneous and very aggressive hot break like foaming session that start, stop and then start up again until it finally peters out. Wondering what this is since I already had an aggressive Hot Break during the beginning of the boil? Should I be concerned? Should any action be taken if concern exists? And what would be that action? P.S. I am currently boiling very aggressively on my 15 gallon Kettle Electric B.I.A.B. system.

 

[BeerSmith]

I'm not sure what the cause might be - I typically get a nice hot break up front when the boil starts, but I usually don't see a second one.

Perhaps someone else can comment?

 

[BrewCat]

I've seen foaming during hop additions but not spontaneous flareups. Im wondering if there are cold spots in your kettle that are heating up at different times. what type of kettle and burner do you use? do you circulate or stir your boil?

 

[FatherSonBrew]

We currently have a 15 gallon 220vac Electric B.I.A.B. configuration with adjustable recycle wort capability on top and bottom of kettle. Brewhardware metal wire screen platform sits over element and under bag. Usually I only run the pump the last 15 minutes of Boil.
I am wondering if the vigorous boils we have started leaning into are the catalyst for this phenomenon.
I have seen this multiple late aggressive come and go foaming thing off and on during our 8 year brewing experience. It is not really a new thing. We have seen it on other systems. Just more often recently. Two variables I can think of is Pilsner malts, longer boils and vigorous boils. Thanks for your response. FS&HS

 

[brewfun]

It all boils down to a combination of surface tension, sugar density and hop isomers. Plus, with the addition of your screen, convection becomes the catalyst in the "spontaneous" foam creation.

As you boil, the concentration of sugars increases the temperature required to boil. No by much, maybe a degree or so, but this requires more heat to create convection. With the screen a separation occurs because the wort can't freely move, so, as the heat accumulates under the screen a slight heat differential occurs, but it's not moving as well to distribute the heat. Once the hotter wort finally hits the lower temperature wort, a fast convection occurs and you create surface foam. Add in foam positive elements like proteins, hop isomers and chloride, the foam doesn't break as fast. Other factor like air humidity and how fast air moves over the top of the boil are contributing factors, too.

 

[MaxStout]

I've seen that sometimes. At the beginning of the boil the hot break will cover the surface and rise some, then retreat to the sides for a while. A little later it will expand over the entire surface again. I chalked it up to convection currents and dynamics from the rising steam bubbles.

A few drops of Fermcap-S will knock it down.

 

[FatherSonBrew]

I have also seen some weirdly aggressive spontaneous very very foamy breakouts with late boil hop additions. The ONE thing I am doing different is very aggressive boils per some BeerSmith blogs I listen too. Having second thoughts about aggressive boils and thinking that I may very boil rate per beer style. Lighter grains hotter boil, medium grains gentle boil. I steep darker grains in last 15 to 20 minutes of Mash (bag in a bag). Problem is BeerSmith equipment profile also has to be adjusted, because boil off water loss varies with boil rate.

 

[brewfun]

Having second thoughts about aggressive boils....

I don't see any advantage to a boil that is greater than 8% evaporation per hour. DMS is scrubbed at that rate and concentration is still good. Couple that with improving mash efficiency and there is less need to heavily concentrate wort for gravity.