Crashing lager yeast and head retention

I have a head retention question, and not finding an obvious thread with the search:

Made a Helles with ~15% Carapils (I know.. way too much).. everything was okay.. it dried 1.054->1.010.. but I would have thought the head formation would have been huge and sustained. Primary for 3.5 weeks (49°F), diacetyl (59°F), kegged and slow carbed to 2.7 volumes over two weeks @ 35°F; its only been lagering for a couple of weeks at 35°F, so there is that. Oh, clean glass and all that; lacing is there but the head dissipates much faster than I was expecting with that much Carapils. FWIW, I used WLP810 San Fran Lager.

Somewhere (cant find it) I think Ive read that rapid crashing (60°F->34°F overnight; dont know the rate) of lager yeast after diacetyl rest causes protease enzymes to be released, continuing the consumption of proteins necessary for head retention.

Any confirmation, or sources, on this one? Should I slowly drop to lagering temps (like max XX°F per day or hour)?

So how long are we talking here? 4 to 5 minutes and other than foam clinging to the sides of my glass, my head is gone.
Seems normal to me.

Head retetion can be affected by the boil, yeast pitch rate, fermentation temp., wort aeration etc...

There are so many factors involved it is REALLY hard to tell.

Yes, Briggs mentions this in Brewing, Science and Practice... that crash-cooling lager yeast can cause the yeast to release proteolytic enzymes, thereby affecting foam stability.

menschmaschine said:

Yes, Briggs mentions this in Brewing, Science and Practice... that crash-cooling lager yeast can cause the yeast to release proteolytic enzymes, thereby affecting foam stability.

Click to expand...

So the recommendation is to slowly step down to lagering temp. to avoid the release?

Soperbrew said:

So the recommendation is to slowly step down to lagering temp. to avoid the release?

Click to expand...

Yes, 3-5°F per day seems to be a good range.

However, some homebrewers cold crash lagers and report no noticeable effects in foam stability. I prefer to slowly cool them... not only for the potential of proteolytic enzymes, but lager yeast slowly eat away at various sugars during lagering and shocking them out of suspension seems counterintuitive.

I try to gradually lower mine, too, but sometimes can't. I haven't had any foam stability issues though.

menschmaschine said:

Yes, 3-5°F per day seems to be a good range.

However, some homebrewers cold crash lagers and report no noticeable effects in foam stability. I prefer to slowly cool them... not only for the potential of proteolytic enzymes, but lager yeast slowly eat away at various sugars during lagering and shocking them out of suspension seems counterintuitive.

Click to expand...

Thanks for the info. It was probably some post of yours that I read

Some extra reading here http://forum.northernbrewer.com/viewtopic.php?f=1&t=81509&p=762866&hilit=+cold+crashing#p762866

I think a few more weeks age at cool temperatures will help with the head retention. All of my beers have poor head retention until they're aged a bit. Even some PVPP can help.

FWIW I don't think i've ever had a commercial lager that has held a full head of foam for more than a minute, even the finest German ones.