Yeast Fermentetion Temp - How low do you go ?

[hamster]

I made a Kolsch recently with Imperials G03 Dieter yeast which had temperature range of 16-20c. The beer though had a huge amount amount of banana flavor & aroma too it. Whilst my ferm fridge was set at 18c the extra heat generated through fermentation clearly put it higher and pumped out banana esters !

Onto my second attempt...

I've made one up and pitched the yeast @19c and instantly dropped my fridge down to 15c to attempt to get the yeast to ferment at the coolest possible temperature. My problem is 48 hours in and I've had no activity... Gravity reading is the same, 1.046, I don't rely on the bubbles !

Now with most strains wouldn't the yeast still ferment even at a slightly lower than recommended temperature ? I was hoping once it had kicked off, with the extra heat generated it would ferment at that 16/17c mark

I'm concerned now that I've murdered or done something to my yeast...

Whats your experiences ?

I've increased my fridge temp by another degree and shaken my FV to try and generate some activity so I'll see how that goes...

Also ordered some fittings so I can blow CO2 into my dump value for the Brewtech Chronical to properly stir things up... That'll take a few days though and worried my wort could sit around and spoil

 

[Dutto]

I'm still reeling from the amount of interference that you are putting your brews through; plus, what happened to the first brew?

1. "Whilst my ferm fridge was set at 18c the extra heat generated through fermentation clearly put it higher ..."
   • How? If the Set Point of the fridge was at 18*C how come it didn't control the temperature?
2. "I've made one up and pitched the yeast @19c and instantly dropped my fridge down to 15c to attempt to get the yeast to ferment at the coolest possible temperature.
   • Why? As you pitched the yeast at 19*C what was the point of dropping the temperature before fermentation was established?
3. "Gravity reading is the same, 1.046, I don't rely on the bubbles !"
   
   • Why? I have had many brews where I haven't seen a single bubble come out of the Blow Off Tube; the only indication being the formation of a krausen and an increasing level of trub in the bottom of the FV. Normally, I would never open up the FV to check the SG before a couple of weeks had passed.

With only 48 hours since you pitched the yeast into the second brew I suggest that you:

• Check that your temperature probe is accurate.
• Increase the FV temperature to 20*C.
• Leave it well alone for at least a week - even if there is still no sign of life from the brew.
• Pray that you haven't introduced an infection by opening up the FV to get an SG.

If there is no sign of fermentation after a week then you probably introduced a load of dead yeast cells at the beginning of the process (assuming that you didn't kill them off by pitching them at too high a temperature) because dropping the temperature will normally only put the yeast into a state of hibernation.

I'm still intrigued as to what happened to the first "banana" brew. Lot's of brews taste and/or smell terrible at some time during their production but a few months of conditioning in a cool and dark place can change them into something special.

Enjoy! :thumb:

 

[hamster]

1. "Whilst my ferm fridge was set at 18c the extra heat generated through fermentation clearly put it higher ..."
   • How? If the Set Point of the fridge was at 18*C how come it didn't control the temperature?

If you check your wort temperature at the beginning of ferementation it will not match that of a stat and the fridge. It's always higher, typically I've found over the last few weeks this can be as much at 3c !

If you want accurate temperature control you need to invest in something like the SS Brewtech FTSS system...

1. "I've made one up and pitched the yeast @19c and instantly dropped my fridge down to 15c to attempt to get the yeast to ferment at the coolest possible temperature.
   • Why? As you pitched the yeast at 19*C what was the point of dropping the temperature before fermentation was established?

My fridge cools wort slowly I was hoping that pitching yeast would start then off before the temperature reached the lower value. As per above probably settling at 16c due to heat produced through ferementation...

1. "Gravity reading is the same, 1.046, I don't rely on the bubbles !"
   • Why? I have had many brews where I haven't seen a single bubble come out of the Blow Off Tube; the only indication being the formation of a krausen and an increasing level of trub in the bottom of the FV. Normally, I would never open up the FV to check the SG before a couple of weeks had passed.</QUOTE]

The only way to tell if fermentation is taking place is to take a gravity reading. You can't see into my SS Brewtech Chronical, so who said I'd opened it up and exposed it to O2 and other air born nasties ;o)

Taken gravity readings through the racking port, I always make 500ml more than needed so I can take readings throughout the process...

With only 48 hours since you pitched the yeast into the second brew I suggest that you:

• Check that your temperature probe is accurate.
• Increase the FV temperature to 20*C.
• Leave it well alone for at least a week - even if there is still no sign of life from the brew.
• Pray that you haven't introduced an infection by opening up the FV to get an SG.

If there is no sign of fermentation after a week then you probably introduced a load of dead yeast cells at the beginning of the process (assuming that you didn't kill them off by pitching them at too high a temperature) because dropping the temperature will normally only put the yeast into a state of hibernation.

I pushed my temp up a few degrees, I don't want it fermenting hotter that absolute minimum. Temperature is taken from the thermowell so not going to get much more accurate...

Yeasties certainly are not dead, they were from a 2 litre starter that had finished and settled out in a fridge for 24 hours so I could tip most of that wort away. Again they had been brought back up to temperature for at least 8 hrs before pitching so no massive thermal shock...

Good news is the beer is down to 1.040 this morning so some fermentation has taken place. Temperature reading of the wort was 17c, or just under. Once fermentation really kicks off which will rise the temp again I'm going to try drop the temp on the fridge by a degree to keep it on or below 17c...

I think I need a tilt... :)

 

[Dutto]

In that case, all I can say is "You worry too much."

 

[hamster]

In that case, all I can say is "You worry too much."

Probably true !

Anyone else tried fermenting as low as possible with any yeast ?

 

[JerryP]

Ideally you want to be controlling for the temperature of your beer, not the air around it.

Either way, the G03 yeast from Imperial is, according to their site, ideally fermented at 16-20C. So being at 15C in the fermentation fridge is not going to harm it - but it may make it start a little slower. But, as you comment above, once it is going the temperature of the beer will be a little higher as fermentation is exothermic. How much higher depends on a number of factors and is not always easy to predict.

I will ferment at the lower end of the range when i want a cleaner beer (less esters), raising it to the high end once around 2/3 of the way through to ensure the yeast stays active and cleans up.

Either way, there is no reason why your process so far will have killed or harmed the yeast. So relax, don't worry and have a homebrew!

 

[hamster]

Thanks JerryP ! That's the experience I was after...
I always took the temperature ranges on yeast as a guide but assumed (never tested or read it would) that it would still ferment at a lower temperature (within reason) but slower. I want to try ferment this as clean and with as lower ester production as I possibly can.

I'm used to yeast kicking off within hours as I pretty much always use a starter with clean fresh yeasties...

Now it's started I'm happy but did take 36-48 hours to really do anything, hopefully now its' started it'll quicken up just need to keep an eye on that temp !