saflager 34/70 cold pitching method question

[GalBrew]

Pic Blue mountain on left Coles on right the Blue was sweet then suprisingly bitter while the coles was pretty plain bit sweet not very bittter at all. I was really suprised at the different colours!

Oxidation much? Seriously +1 to the above comment. Also explains your 'sweet' tasting beer. Jebus....... :unsure:

 

[Ducatiboy stu]

Maybe over time the hop oils have reacted with the malt.

Either that or the coles tin was misslabeled..

 

[Rocker1986]

I was led to believe malt extracts will darken with age. That may be part of the reason for it too, given it's a couple of years out of date.

 

[GalBrew]

Or it has been sitting in a cupboard or a LHBS shelf in the sun for the last 2-3 years and has slowly oxidised over time.

 

[Ducatiboy stu]

Hard to oxidise in a vacume sealed tin...but anything is possible

 

[GalBrew]

Hard to oxidise in a vacume sealed tin...but anything is possible

So now we are saying that tins of goo don't oxide on the shelf? I am pretty sure they aren't vacuum sealed either. They are canned and probably pasteurised in an autoclave, but I have never heard telltale 'whoosh' of air enter a tin of goop upon opening. I will even reference 'the Palmer' on this one (I apologise for being lazy and not using the newest version but I am going home).

http://www.howtobrew.com/section1/chapter3-2.html

 

[Adr_0]

from what I read, you should only really cold pitch if you are 100% confident you have the volume of yeast cells. a pack of dry yeast has viability but I would be a bit nervous about the cell count so would quietly be either pitching at fermentation temperature or a couple of degrees warmer... as everyone has suggested above.

The 'waiting 12hrs' is also more for signs of activity before you change the temperature to fermentation temp (presumably 10°C). I would agree with this with a warm pitch.

The cold pitching thing... I'm not so sure about it. What's wrong with pitching the correct cell count of active yeast at the temperature you will ferment?

I have just done a pils, which was 1.5L, 2.5L then 2.5L (to freshen it up, not so much for growth) stir-plated starters. 50L of 1.045, so that should have been about 1.5mil/°mL. I pitched at 8°C, waited until there was pressure in the airlock after swirling a few times - ended up being 12 or 18hrs... not at my computer so can't remember - then warmed up to 10°C.

Comments? The beer is ridiculously clean, but still has buttery notes - this is diacetyl, not DMS as I think has been confused above. Not a hint of ester. Diacetyl did get a bit stronger, but I haven't tasted since dropping to lagering temps.

I would say it is the cleanest lager I've done, but previous lagers have only had about 1mil/°mL and I would say this, then pitched at correct fermentation temp, is more important than cold pitching. Anecdotal a bit, but I haven't seen a lot of science about the cold pitching. Thought I would give it a go though.

 

[JoeyJoeJoe]

I have been doing some more research on this topic and found this http://www.fermentis.com/wp-content/uploads/2012/06/TT_Booklet_En.pdf.

It is a bit of guide that fermentis put together anyway if you jump to page 6/7 it seems to indicate that they recommend rehydrating at 23C and then pitching the yeast into the wort when it gets to 12C. This seems like a big temperature change but I guess they know what they are up to.

I also found this graph very interesting. It really shows that yeast starts kicking the diacetyles ass when they lift the temp up to 14C (they recommend 48 hours at 12 then up to 14.)
The start time was pretty close to what I experienced as well about 24 hours before I saw air lock activity.

 

[Rocker1986]

Yes I figured the active fermentation producing heat would be the cause of the temp rising faster and therefore the fridge kicking in more often. It just doesn't follow any logic to me that just because it's fermenting, the probe measures the temp differently to when it's not as active, especially when it is causing the fridge to come on more often to bring it back to the desired temperature. I'm not arguing because I haven't tested it, it just seems weird. But, as I said, next brew I will take a reading while it is actively fermenting to see if the temp of the brew is the same or higher than what the STC reads. If it is higher then I'll drink a six pack of VB cans

Well, it appears at least for my set up and equipment, that I was right. I have a brew in the FV which is in its second day of fermenting, quite a thick krausen (grav reading is 10 points below OG so it's going nicely), temp probe taped and insulated on the side measuring 18.2C, took a sample and took the temperature at 65F (or 18.3C). I don't know whether this is due to the way I insulate it, covering it with a reasonably thick layer of foam and taping it on with big thick plastic tape, but it's accurate.

Not saying it'll necessarily be like that for everyone, as obviously others have had different experiences, so obviously you'd set it up to suit your own situation, but at least now I can be happy in setting the thing to the temp I intend to ferment at and not worry about it going 2 or 3 degrees higher. And I don't have to drink that 6 pack of VB cans. :lol:

 

[JoeyJoeJoe]

Thanks for letting us know.I have ordered a digital temp probe on ebay that I will be able to stick down the air lock so I will report back next time I have a fermenting brew (current one is 10 days in so very little activity).

 

[Rocker1986]

No worries. Yeah, that would be the most accurate way of measuring it if you can do it without risking infections and such.

I can't remember whether I have tested it on an actual fermenting brew before or not, but I will do it again on the next couple of brews as well to see if it is consistent. It just defies logic to me, which is why I decided to test it, that just because the brew is fermenting it'll measure differently. The probe is measuring the same way regardless. The fridge is coming on more often to keep it down. Now if the temperature when it's inactive is coming through the plastic accurately, it surely follows that it would come through accurately during fermentation as well, which it did today at least.