Brewing with anti foam: is it good or bad?
By Moritz Kallmeyer
Chief Brewer of Drayman’s Microbrewery, Silverton, Pretoria, January 2013
I first read about anti foam in the book Basic Brewing Science by Dr Trevor Wainwright. He classifies it as a processing aid, meaning no traces of the additive is found in the final beer. I view malt husks in much the same light. I’ve been using it for about a year now and probably would never go without it again. During fermentation CO2 produced causes the beer to foam. When the foam collapses at the end of fermentation, a considerable amount of the material forming the bubbles (mainly protein and hop components) is left on the walls of the fermented – and inside the domed roof in case of a closed fermenter. As a result the packaged beer (especially on high adjunct ratio beers) may not be able to form a good foam head and some of the bittering material is lost in the fermenter. The material deposited on the walls is often difficult to clean off and large fermenters are needed to prevent over-foaming. Even over sized fermenters are no guarantee to prevent over-foaming and this always results in beer loss and cleaning problems. Walking into the brewery in the morning, finding half your brew on the floor is not a pretty sight.
At home brew level there would certainly be no more clogged bubblers or blocked blow off tubes! When there is fat from food or lipstick on a beer glass it destroys beer foam. Anti foams are food grade silicone oils or hydrocarbon oils with additives that act in the same way and are normally preserved with sulfur dioxide. Anti foam allows CO2 to escape from the beer without forming stable bubbles. The brand name that I use is called “Fermcaps” and contains an emulsion of 20% Dimethyl Polysiloxane. Since I have experienced frequent problems with boil-overs at Drayman’s (because of an undersized kettle), I was delighted to learn that antifoam is also used in the wort kettle to prevent over foaming and to allow the water to evaporate more quickly. The antifoam added are absorbed onto the yeast and filter material and none is supposedly left in the finished beer.
The word antifoam is thus a bit of a misnomer because the foam on the end-product beer is usually improved. The reason is that less of the head forming protein which is good for foam has been lost during fermentation and transfers.
Other advantages which I have discovered:
- Improved yeast separation at the end of primary fermentation which allows easier collection into buckets.
- More complete yeast removal from the FV is possible because of the slipping effect, lack of sticky adherence to the cone.
- Beer drops bright even in the primary FV during the diacetyl rest period before racking.
- More complete fermentation, yeast tend to stay in suspension for longer.
- Faster transfers due to no foaming.
- Improved filtration due to more yeast that is removed at primary yeast collection stage and less work for the added finings.
- Lower hopping rate to achieve the same bitterness level.
- Those who use plain caustic in a CIP system know how much time is wasted with foaming. When cleaning the fermenter I found a carry over of antifoam into the CIP caustic tank resulting in less caustic wastage and more efficient cleaning.
- For reasons unknown the caustic storage tank also drops bright which allows me to purge the bottom of old dregs, top up the strength and re-use the caustic almost continuously.
Warning! Reception vessels to be CO2 blanketed or use counterpressure. Because of a lack of foam coverage during transfers, there is a risk of oxidation!
Like with all processing aids the challenge is to find the absolute minimum dosing rate for maximum efficiency. Like usual I question any suppliers dosing rate! With Fermcaps which I have been using, I initially halved the suggested dosing rate and still picked up problems. I also added Fermcaps to both the boiler and the FV, thinking it would “degrade” during boiling. In the supplier’s spec sheet, no mention is made of the fact that if you added antifoam to the kettle there is no need to add it to the fermenter again. I found that there is a larger than anticipated carryover effect, because of the adherence to the yeast cells – which is subsequently re-pitched. After a few batches the beer had a very faint but certain oiliness to it and the foam head was affected negatively. I thus followed my own brewer’s instinct and kept cutting back until reaching my current optimum dose rate of 1 1/2 ml antifoam per 900L wort kettle volume. Just add it to the kettle before boilstart.
My own recommendation is thus that you can use antifoam with a clean conscience and enjoy a more relaxed brewing day. No nasty boil over surprises, no early morning beer flooded basements, piece of mind as far as CIP is concerned and a beer in your hand topped with more brilliant white foam bubbles!