Cycles of foaming head on WOW variant

[KayB]

Just a general question concerning a 'strange phenomenon'.
We made up 5 gal of a WOW style (red grape/blueberry) on the 3/12/12 with OG 1092. Soon afterwards we noticed that a foaming head developed (nothing strange in this!) and shortly afterwards disappeared, just to repeat the whole cycle again. Ever since the 3rd when we started, this cycle of building up a head and then dissolving, goes on and on, and we were just wondering if others experienced that as well.
This is not the first WOW we did, and we did quite a lot of country wines, among them loads of WOWs and variations of it during the summer/autumn. In some batches, especially the 5gal ones, we could observe this as well.
Just wondering what the reason for this is.

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[fatbloke]

Perhaps it's something like ambient temperature swings like during the day when the heating isn't on, then it warms up a bit and the yeast gets a bit more active only to cool again over night ?

Dunno how you'd check for that without sitting, watching it and timing the appearance of the foam, or get some clever kit that connects to a timer and thermometer, via a computer to get a record of such events.

Maybe it's only while the brew is still in the early ferment stage. Or just a reaction as above but to do with that particular mix of juices.......

[KayB]

hmmm..... that temperature swings might be the reason was our first thought. As might be seen in the pix, we have a digital thermometer beside the carboys/buckets, and yes, there are 'swings' of 0.1-0.2 degrees... which is in fact not really a 'swing', between 18.8 - 19 degrees Celsius. The time difference between the two pictures is 5! minutes.... so a full cycle is approx. 15-20 min, sometimes less.
As I said, were were just wondering what might be the cause of it, so thanks for the response!

[fatbloke]

Ah, well if it's that quick, maybe its something to do with cellular development etc. Which is just another guess...... I get some weirdness with my meads so both thoughts are nothing more than a "stab in the dark" type guess.

I don't suppose it really matters, as long as it comes out drinkable at the end does it......

One of the guru's might have an idea, but those two are all I can think of.....

[Abervin]

Thats a strange coincidence as I was watching one of my DJs (not a wow) doing the same thing at the weekend Only theory I could come up with, the bubbles became bigger as they got to the top of the pile to the point where they started to burst and the shock wave started bursting the ones below till they were all gone bit like a pack of dominos. Then the cycle begins again.
Its stopped doing it now though

[KayB]

It's exactly as you describe! Something to do with surface tension???

[Abervin]

Probably is.... and rate of fermentation, air temperature, yeast type, must viscocity etc.
I'm sure its nothing to worry about, maybe only your sanity as I thought I was going mad one minute big foamy head then next time you look not a bubble to be seen

[Cellar_Rat]

I would venture it something to do with a gas saturation point being achieved. How much carbon dioxide the liquid will support before it lets go, and then there is a rush.