Wierd Start To Fermentation

[colinw]

The story so far ...

On the Saturday I made my Squires Golden Ale recipe (as posted in the recipes forum last week). The mash, sparge, boil, chilling & transfer to fermenter were "by the numbers" with no drama.

I aerated & pitched some nice active 1056 at about 8:30PM, with the wort at 22, leaving the fridge set in the 18C range. Sunday morning around 8:00AM the airlock was bubbling and a krausen was starting to form. I got kinda busy after that and didn't look in on it again until yesterday (Monday) afternoon at about 4:45PM.

Fast forward to coming home from work Monday afternoon:

I expected to be greeted by an ale at high krausen, or even starting to slow down. I nearly always get complete fermentation of ales within 3-4 days with slow activity up to about day 10.

Instead I was greeted by an almost identical pattern of froth to when I checked on Sunday morning, and just slight airlock displacement. The fermenter appeared to have a considerable amount of yeast in the bottom. Ok, I thought, maybe the lid isn't sealed properly (common with my fermenters), so lack of airlock activity means nothing.

BUT, here's where it gets wierd!

At that point, I moved the fermenter around in the fridge so I could get to the tap to draw off a sample to check with my refractometer.

On being disturbed, there was a sudden burst of airlock activity which didn't die down. For the next hour or so the airlock bubbled so vigorously that nearly all the water was thrown out of the airlock, and a good 2 inches of krausen formed. Before going to bed I refilled the airlock, which continued to bubble vigorously at the rate I expect to see with an ale when my fermenter is actually sealed. This morning the krausen was still up at 2 inches and it was bubbling at about the normal rate for this stage.

The sample I drew off shows only a couple of points of fermentation up to last night.

SO - how the hell can a nearly inactive fermentation suddenly burst into activity so quickly just as a result of moving the fermenter? It literally went from little activity (and the sample showed a drop from 1.045 to about 1.043 in 2 days) to behaving perfectly normally, in a matter of minutes, after moving the damn thing.

As Rove would say ... what the????

I can only figure I had a long lag time for some reason, and somehow ended up with the wort super-saturated with CO2, and possibly the yeast flocculating due to stress induced by the CO2? Disturbing the fermenter appeared to cause a very vigorous outgassing.

Anyone else ever seen anything like this? It has me beat!

cheers,
Colin

 

[Stuster]

Weird indeed. I've never had a fermentation like that, thankfully.

I think your hypothesis is probably right. Is it possible that the airlock could have been blocked at the bottom? This could explain the build up of CO2. Maybe moving it unblocked it. :unsure:

 

[colinw]

I didn't think of a blocked airlock. That would fit.

The change was almost like opening a bottle of softdrink which has been shaken up.

On moving the fermenter, the airlock suddenly started bubbling so vigorously that it was foaming out. Most of the fluid in the airlock was expelled in a few minutes, and it had expelled so much that it no longer bubbled within an hour.

The wort surface went from some low foam (like the first stages of krausen forming) to 2 inches of high krausen.

Before disturbing it, the bottom inch of the fermenter had a lot of yeast (or break material) in it. After it took off that was disrupted and the whole wort was uniform.

Whatever it was - I have never seen a beer behave like that before and hope I never do again.

I shall report back on the progress & finished beer ...

 

[Finite]

I consolted my brewing book for this:

im no expert by any length but here what i think could have happened:

In the time you were busy and not checking the brew the krausen rose to the airlock (not uncommon with alot of beers) as it reached the top of the airlock in caked on (for lack of a better word) to the funnel of the airlock, blocking or at least almost compleatley blocking the hole. (that krausen that can collect on the airlock can be very stubbon to get off if left to dry)

Meanwhile the yeast is still chomping away producing carbon dioxide which is filling up the fermenter and creating alot of pressure. The carbon dioxide cannot escape so higher levels than normal are being absorbed into the beer. Enclosed fermenters and maturation vessels in brewerys are fitted with automatic gas pressure regulators that can be set at a chosen pressure. Asumming that the gas above the beer is pure CO2 then it will begin to disolve into the beer. As i understand, increasing the pressure (or in your case blocking the airlock) will lead to a liner increase in the wieght of CO2 dissolved in the beer. An increase in tempeture will result in a non-liner decrease in the ammount of CO2 dissolved. There is actually a formula which allows you to calculate the amount of Co2 in the beer baised on that theory and another constant (which is tempreture dependant).

When you went to move the fermenter, the pressure from each hand on the side of the plastic (im assuming plastic) bent inwards just enough to push the gunk in the airlock out (ive noticed alot that when i move a fermenter even lightly i create enough force to push out some CO2 which stimulates the airlock) which in turn released the carbon dioxide and as such the beer begain releasing the excess CO2 inside it. Beer is capable of holding carbon dioxide in a supersaturated state, so rapid release of pressure or increase in tempreture does not immediatley lead to reduction of CO2. As we know beer goes flat over time.

I would liken this last bit to what happens when you over carbonate a beer bottle, It appears normal but when you uncap it because its overcarbonated the beer just gushes out in foam.

Anyway i could be totaly wrong or partly wrong thats just my thoughts. Again i know nothing compared to alot of the blokes here

 

[colinw]

I'm tending to agree with the blocked airlock theory.

The airlock blocks, leading to higher pressure than normal, hence lots of CO2 in suspension, slowing down the fermentation as a side effect.

I move the fermenter, which is suddenly freed up, leading to a rapid outgassing. This explains both the expulsion of nearly all the fluid in the airlock, and the sudden formation of a 2 inch head of foam on the beer.

With the airlock freed up, the normal dynamics of CO2 are re-established, and the fermentation proceeds as normal.

Wierd!

 

[warrenlw63]

Colin.

I've had a few starters display this trait but not do it in the actual primary ferment.

Swirl the starter, blow the water sky high from the airlock and then a huge amount of foaming. Some even coming through the airlock (2 litre starter in 5 litre demijohn ).

Only thing I can think of is entrained cO2 in the ferment for some reason?

Warren -

 

[colinw]

Wow!

The interesting thing is that the refractometer reading, and the appearance of what looked like premature flocculation, tends to indicate that the fermentation was stopped by all that CO2.

Once it started, it really took off and was going along fine this morning.

 

[colinw]

Update: its fermenting along beautifully now, and was down to 1.028 from 1.043/4 within 24 hours of bursting into life in such an odd way.

One thing: has anyone noticed a change in the aroma of the 2005 crop Amarillo hops compared to 2004? 2004 seemed to have a very rich "stone fruit" character, with the 2005 I swear it is more pineapple like. Although I do find hops aroma during fermentation is rarely representative of the finished beer.

 

[Jens-Kristian]

premature flocculation

Hehh . . hehhh - sounds naughty. :chug: Right, back to milk.

I've never heard of that happening before either, but I'm sure the explanation given so far must be what caused it.

It'll be interesting to see if this process will have some form of impact on the taste of the beer? I've been trying to figure out how it might do something tastewise, but I really am no wiz on chemical processes.

Is this a beer you've brewed before? If so, please, please, please let us know if you notice any changes in the outcome, because I'm always extremely interested in hearing what the outcome is when something 'unexpected' happens.

Cheers,

Jens-Kristian

 

[colinw]

Its the first time I've made the recipe, so no baseline for comparison there. Also, I usually use US-56 dried yeast rather than 1056 liquid, so differences in flavour profile could be attributed to that as much as the funny start.

As of last night it was down to 1.010, and the sample tasted perfectly normal with no preceivable off flavours. The fermentation from Monday night when it burst into life to last night was normal, and took the 3 days I generally expect my ales to take ... just delayed by about a day from normal.

I'll put this down as a one off anomaly. The proof will be in the drinking, but at this stage it looks good.