Does cold crashing starter cause stress (heat shock proteins)?

[bigskygreg]

I usually cold crash my starters depending on my brew schedule. By putting the starter in the fridge and dropping the temp so fast, are we causing stress on the yeast that will affect our main batch?

At first thought, I would think yes, but... So many people do this. I also would think that as long as fermentation is complete, the yeast would already be going dormant and be less susceptible to stress of temp drops.

Also, if I use a high flocculant yeast, should I even bother cold crashing if brew day is 24 hours or so away?

Thanks for the input!
Cheers

 

[ColoHox]

The cold response in yeast mostly has to do with membrane fluidity and carbohydrate conservation. The heat shock proteins are involved in maintaining normal cellular protein function and repairing heat damaged proteins where as cold has more of a preservative effect, although there are some analogous responses.

The biggest reasons most people cold crash is to drop yeast out (not as much of a concern if the strain floccs well), and to not pour spent starter wort into their beer. Both are really not a big deal.

 

[Cyclman]

My understanding is that heat pisses off yeast, cold calms them to sleep, so I think temperature stress is mainly when yeast are too hot.

Of course, if you don't have a belgian hot enough in fermentation and they drop out before you reach FG, that's not too good.

 

[BigFloyd]

By putting the starter in the fridge and dropping the temp so fast, are we causing stress on the yeast that will affect our main batch?

No. They just go dormant.

A regularly cold crash my batches in the primary to clear the beer and firm up the yeast/trub layer. I take the 67-68*F bucket o' beer out of the fermenter chamber and put it straight into a 35-36*F fridge for 5-7 days. I've yet to detect any sort of problem with the practice.

 

[Black Island Brewer]

No. They just go dormant.

A regularly cold crash my batches in the primary to clear the beer and firm up the yeast/trub layer. I take the 67-68*F bucket o' beer out of the fermenter chamber and put it straight into a 35-36*F fridge for 5-7 days. I've yet to detect any sort of problem with the practice.

What was your control group to compare the cold-crashed beer against? Did you split the batch and gradually chill half and rapidly chill the other half? Yes, I know I'm being a bit of a smart alec, but how can anyone really know there's a problem unless they've done a side by side comparison?

I've heard from pro brewers that they chill at the rate of one degree per hour in order to eliminate the off flavors caused by rapid chilling yeast.

 

[BigFloyd]

What was your control group to compare the cold-crashed beer against? Did you split the batch and gradually chill half and rapidly chill the other half? Yes, I know I'm being a bit of a smart alec, but how can anyone really know there's a problem unless they've done a side by side comparison?

No. I'm not that hung up about it.

I've heard from pro brewers that they chill at the rate of one degree per hour in order to eliminate the off flavors caused by rapid chilling yeast.

I've heard all of this before, but I've never seen anyone actually describe what the particular off flavor is supposed to be. IMO, the burden of proof is on those claiming that you can indeed get some sort of negative flavor profile by doing this. If there's an off-flavor caused by rapid cold crashing, my taste buds have never ever picked up even the faintest hint of it.

 

[billl]

Of course yeast find big temps swings stressful. They go dormant as a result of the stress. That process does take some toll on them and they don't restart as quickly as if they were in full swing already. Of course, they are really, really good at going dormant and reemerging. A couple thousand years of selective breeding has resulted in yeast that can easily take that kind of abuse and still produce tasty beer.

 

[SpeedYellow]

Many folks cold crash their lager yeast starters yet still get fermentation to start in 12 or so hours, which is just fine. I'm working on testing a theory that cold crashing to fridge temp (about 35-40f?) is fine but 32f causes a deeper dormancy. I've never read or heard this, but I think I've seen it a couple times... still trying to confirm.

 

[Black Island Brewer]

I've heard all of this before, but I've never seen anyone actually describe what the particular off flavor is supposed to be. IMO, the burden of proof is on those claiming that you can indeed get some sort of negative flavor profile by doing this. If there's an off-flavor caused by rapid cold crashing, my taste buds have never ever picked up even the faintest hint of it.

I too would like to know if there is a difference. But you said in your original post

I've yet to detect any sort of problem with the practice.

but without comparing against a control, none of us will detect a difference or a problem. As I said, I know pro brewers who have said it makes a difference. For all I know, the difference may HELP some styles!

The closest I've found to a description of what is going on and what one might taste was that rapid temperature changes can cause SOME yeast cells to autolyse, and contribute the flavors associated with autolysis. Like you, BigFloyd, I've never tasted it in my rapidly chilled beers. But I can't assert that it hasn't affected my beers, because I've never had a control.