Time Frame for Chilling: A Musing.

[Not For Horses]

Dedicated to Dave70.

Thought I'd kick this on off with a few of my thoughts.
Note these are just my thoughts and understandings based on things I have read and are not necessarily all facts.
I should also point out that my experience with no chill is fairly limited.
This discussion should also not include any issues arising from sanitary practices. We should assume that whatever method you are using, you are doing it cleanly and correctly.

Chilling (fast or slow), as best as I can gather, serves a few purposes for us as brewers.
One being getting the wort to pitching temp so we can bang in the yeast and let it make beer. This does not require a time frame as such. So chill or no chill is not going to make any difference which I suppose is why some like no chill. You can brew when you can and pitch when you want.

Another reason for chilling is to stop the isomerisation of alpha acids from the hops. Isomerisation follows an exponential curve so, even at room temperature, alpha acids can still be isomerised. But this curve has a sharp decline around the 80c mark so for the purposes of determining IBU, we can say that isomerisation is negligible below 80c. Time frame here is important. The amount of time taken to get from boiling to <80c is going to affect the amount of alpha acid that is isomerised. This is why most people accept that a flame out addition of hops when no chilling is equal to a 15 to 20 minute addition when chilling.
You should probably account for this when chilling as well. Take note of how long it takes to get below 80c. If you were using a plate chiller and you take, say, 15 minutes to chill the whole batch, then you would effectively have a 5 or 7 minute addition. I think.

Following on from isomerisation temperatures we get to aromatics. Hop oils are volatile oils. This means that they are readily evaporated and, in our case, are easily carried away by steam. So it stands to reason that the faster you can get your cauldron to stop steaming, the less volatile oils you will loose.
Heat also causes volatile oils to break down into other compounds. This breakdown will still occur inside the no chill cube so it's not just a case of volatile compounds being reabsorbed into the wort as it chills.
So again, the rate of chilling is important as it will affect the extent of evaporation and breakdown of volatile oils.

As far as I can gather, the speed of chill does not affect the formation on cold break. And before you point it out, I am well aware that Palmer says it does.

As I already said, these are just my thoughts and I'm happy for the discussion that will inevitably follow. And I'm always happy to be corrected on anything.

Discuss.

 

[Dave70]

Phew...

I thought I was about to be satirized..

 

[quadbox]

Probably should be some mention of DMS formation here too...

 

[manticle]

Why should there be mention of DMS formation?

 

[Vini2ton]

Isn't DMS a boil related thingamadoover issue?

 

[JDW81]

Probably should be some mention of DMS formation here too...

In reference to no chill? Why not throw in C. botulinum for good measure.

What's a chilling topic without some good ole scaremongering?

 

[Vini2ton]

I love you guys.

 

[Camo6]

My mate knew a mate who died of botulism from no-chilling. He would have survived too, but the gladwrap on the FV allowed the toxin to breathe. They suspect the spores were introduced from remnant traces of juvenile feline faeces. How that got there was a mystery as the lid was only ever removed for photos.

 

[barls]

lets keep it on topic peoples.

 

[dago001]

I'm turning my tap on full bore. Just saying.
Cheers
LB

 

[danestead]

Beersmith did studies and determined that at 90 degrees, you extract about half the IBUs you would at 100 degrees, for the same time frame.

Just thought id throw this in there because its relevant.

 

[menoetes]

Good information, thanks. It's good to know about the 80'c thing.

I've been using a cold waterbath to cool the pot containing my wort until I can comfortably lay a my hand on the base of it and not feel too much warmth and I'm guessing that can't be much more than 50'c.

Good to know I'm getting it down low enough, I haven't been sure just how cool I needed to go to stop the isomerisation.

 

[dicko]

Why should there be mention of DMS formation?

From a blog from Brad Smith:

DMS in the Beer Brewing Process

DMS is created whenever wort is heated, so some DMS is present in any beer. DMS is created in the mash, however most DMS is evaporated during the boil, so the boil is the primary place to focus if you have a DMS problem.

The half-life for DMS is 40 minutes, so half of the DMS will be boiled off in a 40 minute vigorous boil. So if we do the math, a 60 minute boil gets rid of 64.7% of the DMS and a 90 minute boil rids us of 79% of the DMS. That is why most experienced brewers recommend a 90 minute or longer vigorous boil.

Since DMS needs to evaporate off during the boil, it is important not to cover your pot. Covering a brew kettle during the boil will prevent the DMS from evaporating and create a beer with much higher levels of DMS.

Rapidly cooling your wort after boiling is also important. The SMM to DMS conversion continues at temperatures well below boiling, so DMS is produced even while the wort is cooling after the boil. However, unlike the mash, DMS produced while cooling cannot be boiled off. This conversion continues even if the hot wort is vented. For every hour you have hot wort sitting around, you will produce approximately a 30% increase in DMS.

During fermentation, CO2 bubbles actually help remove from DMS from the beer. More vigorous ale yeasts tend to produce lower DMS levels. Also different strains of yeast do tend to produce DMS during fermentation primarily by converting DMSO (which does not boil off) to DMS. Lager yeasts and yeasts fermented at lower temperatures tend to have higher DMS production. Certain wild yeasts and bacteria can create high levels of DMS as well.

DMS aromas (including some sulfur or rotten-egg aroma) during fermentation (particularly lagers) are not unusual, so you don’t need to toss your beer out just because you have a DMS aroma during fermentation. Some of this will fade naturally during the lagering process.

Finally, beers with robust flavor profiles (dark beers, strong ales, etc) tend to mask the DMS cooked corn flavor with other flavors such as roast, chocolate or caramel malts. Because of this, high DMS levels are most perceivable in lightly flavored beers such as low-adjunct pilsners, many German lagers, continental lagers and extremely light ales. DMS is rarely a problem in beers that are Amber colored or darker, and also rarely an issue with most robust beer styles.

Controlling DMS – Summary

High DMS levels are most often perceived as a problem in light lagers such as Pilsner and many German lagers
Choose a 2 row pale malt (over 6 row) as a base malt to minimize SMM (a DMS precursor)
Very pale base malts (such as pilsner malt) tend to have higher SMM levels which drives higher DMS production
Avoid using corn as an adjunct with these beers, as it can enhance the creamed corn perception
Boil your wort for 90 minutes or longer with a vigorous rolling boil
Don’t cover your boil pot – leave it open so the DMS can evaporate during the boil
Minimize hot wort standing time by rapidly cooling your wort after the boil
Select a yeast and correct fermentation temperature to minimize DMS production
For many lagers, DMS aroma is normal during fermentation, but it should fade with time as you lager and age the beer
If you brew a beer with high DMS levels (creamed corn aroma) take a close look at the suggestions above, and focus on your boil, as that is where DMS can be most easily controlled. Thanks for joining me on the BeerSmith blog. Check out my podcast or email list for more great brewing material!

Tagged as: Beer, DMS, Dimethyl Sulfide, brew, brewing, homebrew, lager, yeast

 

[manticle]

Yeah I know how it's formed dicko. I also know that with modern malts and an adequate, uncovered boil, it's no more of an issue with no/slow chill than it is with immersion/plate/cf chilling.

 

[Yob]

Grumpy Paul is the new John Palmer

 

[dicko]

Yeah I know how it's formed dicko. I also know that with modern malts and an adequate, uncovered boil, it's no more of an issue with no/slow chill than it is with immersion/plate/cf chilling.

The selection of the type of grain is important in eliminating or at least decreasing DMS however the precursor to DMS which is SSM remains in the wort after the boil and can cause the re emergence of DMS in certain situations of slow chilling.
Without going any further off topic and without wanting to turn this into a chill v no chill debate the use of a base grain that has been kilned at a higher temperature eg Ale Malt as opposed to Pils Malt may go a long way to decreasing DMS.