Hello I have a Scottish 70schilling fermenting at 60f for the pass 5days. An I am wondered when I can start ramping up the temp I doing this to help clean up any Diacetyl or other fermentation byproducts an how high should I ramp it up to?
I raise after 3-4days after the yeast start to slow down. I go from 64-65 to 68-70
So ramp it up by what 2f per day from the 60f upto 70f
That will work. 4-6 deg would be fine.
I just let it free ride to ambient temp 68 or so after 5 days or so. Even lagers I just pull out of the freezer and set on the floor those generally I’ll keep cold for 10 days or so before the d rest. Ales don’t need a d rest anyway I just look as it as dessert time for tired yeast
1 Like
I think about 5 days after first signs of fermentation seems about the right timing. But it’s not that critical either. 4 days wouldn’t be bad. 7 days wouldn’t be wrong either. And even if you didn’t raise temperature at all, that wouldn’t be bad either. It’s all good.
1 Like
Here’s a bit of info that will appear in the couple months in a BYO article I wrote…in effect, cleanup happens all the way through, not just at the end of fermentation. From John Palmer…"Yeast have 3 phases in their life cycle: Adaptation, High
Growth, and Stationary. (See Yeast by CW and Jamil) They do not have a
maturation phase where they clean up byproducts. Adaptation phase is
where they take in oxygen and build sterols and other lipids, assess the
sugar composition and build enzymes, etc. Once those activities are
done, they start the High Growth Phase, eating and reproducing. The
number of cell divisions is limited by their lipid reserves they made
during Adaptation. These reserves are shared with each daughter cell.
When those lipid reserves are exhausted, the cell stops reproducing. In
addition, when those reserves are exhausted, the cell is old and cannot
eat or excrete waste efficiently across it’s cell membrane. A yeast cell
typically can reproduce about 4 times during a typical fermentation,
after that it is old and tired and tends to enter Stationary phase where
it shuts down most of its metabolism and flocculates, waiting for the
next batch of aerated wort. Stationary phase is essentially an
inactivity phase, resting on the bottom.
Like
I said, no conditioning phase as far as the yeast are concerned.
Byproducts can be consumed at any point during the high growth phase,
but they are a lower energy source than sugar, so guess what? Byproducts
are not a biological priority. The brewer therefore needs to plan his
pitching rate and fermentation conditions such that the yeast run out of
fermentable wort sugar before their lipid reserves are exhausted and
they go into stationary phase. Now you have a majority of vigorous yeast
that have only undergone 2 reproductions (for example), the sugar is
gone, and they are still hungry, so they turn to acetaldehyde and
diacetyl as alternate energy sources and maturate the beer. You can help
this by doing a diacetyl rest by raising the temperature a few degrees
after the first half of fermentation, to keep the yeast active and
eating. Where in the fermentation? after the first half, 2/3 to 3/4,
when most of the attenuation has occured and raising the temperature is
not going to cause rampant growth and the off-flavors associated with
it. "
4 Likes
Ditto.
FYI, it will be in an article on fast lager fermentation.
1 Like
So my dessert analogy is correct. The yeast pig out on a big meal and then the host brings out dessert. Not wanting to be rude they eat that also even it is just empty calories. After that they all flocculate down to the couch to watch football and fall asleep.
2 Likes
sounds like a lounge topic…Sneezles61
