Beer head differences

A couple of the beers I’ve brewed over the past few months have ended up with these really beautiful, persistent creamy heads – almost as fine (fine, as in minuscule bubbles) as a nitrogen beer.

I realize the chemistry and physics of head composition is complex, but I’m wondering if anyone has any ideas on how to replicate this?

The two beers were an amber ale and a pale German lager, so I can assume it’s not related to yeast strain, fermentation temperatures/times, or grain bills. I use irish moss in the boil, fine with gelatin and burst carbonate in kegs.

I usually leave my beers under a constant 8-10 psi for serving, and the heads seem to get progressively ‘finer’ over time, perhaps it has something to do with CO2 becoming less soluble, etc?

Actually, those things are exactly what it’s related to.  Here’s an amazing article.  You’ll have to set up a tiral account to read it, but it’s well worth it.

I had the same questions a while back. One of the LODO guys sent this shot from one of the brewing texts.

…and Kai Troester writes this: “The dextrinization rest at 70-72C (158-162F) needs to be held until the mash is iodine negative but may be extended to 45-60 min. Many authors contribute head retention and mouthfeel benefits to extending this rest.”

http://braukaiser.com/wiki/index.php/Infusion_Mashing

I’ve found these factors in particular to be crucial:  mash in no lower than 146°F,  and hold an extended rest around 160°F and mash off at 170°F; ensure correct mash pH, and acidify wort to pH 5.0 10 minutes before end of boil  – this ensures optimal performance of kettle finings and removal of hot break and lipids; a short, low intensity boil (this is probably the hardest thing to impress on homebrewers, and makes a huge difference in many areas;)  rapid fermentation as cool as the yeast can go (this presumes proper yeast handling and health,)  and a period of cold storage (29°-30°F) but not too long (a week or three is good.) These points, of all those in the chart from Kunze and quote from Kai posted by BrewBama,  are process-oriented and can be applied to any recipe;  higher iso-alpha content, malt specification,  and such are just as valid, but can’t be observed in every recipe.

One further process point:  You’ve noticed that the head gets finer over time, and this is indeed because the CO2 is becoming better dissolved and comes out in a finer “bead.”  Even if you burst carbonate quickly, it would help to hold the beer for a period of time at serving pressure and temperature before tapping to permit this to happen.  Or even simpler, just carbonate over a couple of weeks at serving pressure.  The gas will be finely dissolved by the time the beer is ready.  I’ve found this works even better for some reason.