Cooling wort (extract brewing)

Hi,

I've been reading this forum and it has helped me brew some nice beers and troubleshoot several issues, so thanks to all!

There is one subject that I think I can contribute to; cooling wort.

This is the info I've gathered so far on cooling wort;

1.- Luke-warm wort is at the highest risk of bacterial contamination (think of leaving a potato salad at room temperature). It is important to minimize the cooling time so that pitched yeast has the best chance of taking over any other micro-organisms.
2.- Most folks recommend that you experiment with ice/chilled water to get the temp you want when adding the boiled wort to the fermentor (consensus seems to be 1 gallon of ice topping off to 5 gallons with chilled water added, but this does not allays work for me, tending to be too hot and forcing me to cool further with an ice-bath while I hope that bacteria is not growing )

So I thought about it. The volume of boiled wort that goes into the fermentor can vary depending on how much initial water you use (2-3 gallons), how strong the rolling boil was and the altitude at which you brew (evaporation loss), and the temperature of the ice and chilled/tap water based on the fridge/city. Makes sense that the that I have trouble getting to 72.5F by guessing the amount of ice each time !

So, I put my scientist hat on. To first order (treating the mixture as water, witch it is with 95% accuracy), the final temperature (Tf) of the 5 gal wort is,

Tf = Tx*(x/5) + Tw*(w/5) + (0.6*Ti - 80)*(i/5)

Where the temperatures are in C and,

Tf is the final wort mixture temprature. Ale yeast wants it to be ~22.5C = 72.5F.
Tx is the temperature of the wort when dumped into the fermentor (typically very close to 100C = 212F).
Tw is the temperature of the water used to top off the fermentor (~15C for tap water and ~3C for chilled water)
Ti is temperature of the ice (typically ~-19C = -2F)
x is the volume of boiled wort in gallons (typically 2-3 gallons)
w is the volume of top-off water in gallons (typically ~1 gallon)
i is the volume of ice measured before freezing when it was water (typically ~1 gallon)

A few comments about the formula,

1.- I derived this formula, so it may contain an error (beware!). Would be nice if someone could verify it. It seems to work for me.
2.- The boiling wort and top-off water terms are simply a weighted average. The ice term also looks like a weighted average but is a bit more complex; the 0.6 factor is due to the fact that it is easier to heat-up ice compared to water, and the -80 term comes from the energy needed to melt ice into water once it reaches 0C=32F.

Ok, so can this formula be useful? You bet! There are two techniques I've found so far,

Super Express cooling - Put a gallon of ice at the bottom of the fermentor, add the boiling wort on top, measure the volume of the fermentor after that and subtract 1 to get the volume of boiling wort (or simply have a graduated boiling pot), then use the formula to calculate how much more ice you need before adding the top-off water (you'll need a supply of ice cubes with known volumes).

Express cooling - Have a fixed about of ice (e.g. 1 gallons). After boiling is done measure the boiled wort volume (related to the height of boiled wort in the pot). Wait for the boiled wort to cool down and reach the Tx that will produce Tf = 22.5C, pour it over the ice and top off. This works well because (1) the boiled wort is far from room temperature and it cools down very quickly, and (2) bacteria won't find it comfortable to live in the cooling boiled wort. This is my preferred method as you don't need to have a bunch of ice-cubes ready and you can increase the amount of ice so you wait less by making Tx closer to 100C (beware, that you can overshoot and get over 100C for Tx, this means that the volume of boiled wart is too low for how much ice you have; don't panic you can add more water to the wort to change x and heat up the fuller boiling put until you get to the new Tx needed).

Anyhow, if anyone is interested I can publish practical tables or maybe write an app so folks don't have to calculate (not doing that at this point since no one may be interested ).

You can boil, then freeze to make sterile ice.

ajosin said:

You can boil, then freeze to make sterile ice.

Click to expand...

I do this and freeze in either sanitized ziplock freezer bags and/or food storage containers.

ajosin said:

Anyhow, if anyone is interested I can publish practical tables or maybe write an app so folks don't have to calculate (not doing that at this point since no one may be interested ).

Click to expand...

This is fantastic! I've try to do this in my head and have mixed results. Sometimes I'm spot on, but usually I end up with too much ice, or the ice isn't enough and I'm back to water baths (which I usually do as insurance(

Would definitely look forward to an online calculator/app, or even a table.

Thanks for your effort

I'm not into math, so I always just cooled the wort in an ice bath in the sink for 15 minutes, until it was 65 degrees then dumped it into the fermenter and topped up with 65 degree water. Of course, then the entire batch was 65 degrees, perfect for pitching my yeast and no math!

Yooper said:

I'm not into math, so I always just cooled the wort in an ice bath in the sink for 15 minutes, until it was 65 degrees then dumped it into the fermenter and topped up with 65 degree water. Of course, then the entire batch was 65 degrees, perfect for pitching my yeast and no math!

Click to expand...

That will work. Notice that you are using math though. In a brilliant simplification you have taken i=0 and Tx = Tw = 65. That means that,

Tf = 65*x/5+65*w/5 = 65*(x+w)/5 = 65, since x+w =5, the total volume of mixed wort when ice is not used .

With your set-up, if (for example) you had two gallons of ice waiting in the fermentor (-2 F for typical ice), and ended up with 2.5 gallons of boiled wort after evaporation, you would only have to wait for the temperature of the boiled wort to be Tx =120F (or so the unverified general formula says), then dump it on the ice and top off with water. You would be able to get to 65F much faster and reduce the time the wort is between 95-65F when microorganisms would want to take over your sweet wort.

rodisian said:

This is fantastic! I've try to do this in my head and have mixed results. Sometimes I'm spot on, but usually I end up with too much ice, or the ice isn't enough and I'm back to water baths (which I usually do as insurance(

Would definitely look forward to an online calculator/app, or even a table.

Thanks for your effort

Click to expand...

Great, working on it - will post when complete. I'll do express cooling first since seems more practical.

Yooper said:

I'm not into math, so I always just cooled the wort in an ice bath in the sink for 15 minutes, until it was 65 degrees then dumped it into the fermenter and topped up with 65 degree water. Of course, then the entire batch was 65 degrees, perfect for pitching my yeast and no math!

Click to expand...

Just noticed that it only takes you 15 minutes to cool boiling wort to 65F! That it really that fast, it takes me a lot longer... (How do you do it?)

Your just running in circles, there are reasons why seasoned brewers, or in fact most people do not use ice. Eventually you will be going to full boils, thus your ice route is useless, or you'll go to all grain once again useless.

Are your goals to make the best beer possible and learn ways to make the beer better? If so your ice method will not last long. A chiller can be made pretty cheap, or just purchased with no effort and will work great. Its hard to have sanitary ice, and it sure would suck to ruin a batch because of it.

rodisian said:

This is fantastic! I've try to do this in my head and have mixed results. Sometimes I'm spot on, but usually I end up with too much ice, or the ice isn't enough and I'm back to water baths (which I usually do as insurance(

Would definitely look forward to an online calculator/app, or even a table.

Thanks for your effort

Click to expand...

Ok, here is a table that may help. It assumes that you have frozen 1.5 gallons of water to Ti= -2F (typical of freezers) and that your tap water temperature is Tw = 60F (typical of tap water). To achieve an pitching temperature of 72.5F, you need to wait for the boiled volume of wort (x gallons) to cool down to the following temperature before mixing it with ice and tap water,

x(g) Tx(F)
---------
2.0 Not enough boiled wort!
2.1 Not enough boiled wort!
2.2 Not enough boiled wort!
2.3 212 (no need to wait!)
2.4 206
2.5 200
2.6 195
2.7 190
2.8 185
2.9 181
3.0 177

Again, same calculation as above but using 1 gallons of frozen water (instead of 1.5),

x(g) Tx(F)
---------
2.0 188
2.1 182
2.2 176
2.3 171
2.4 166
2.5 162
2.6 158
2.7 155
2.8 151
2.9 148
3.0 145

You can see it is less risky to use 1 gallon of frozen water (since there is little risk of over-cooling), but you'll need to wait more.

For the general situation I would have to write an app. I can write a java applet for that and put it on-line at a later date.

Maxkling said:

Your just running in circles, there are reasons why seasoned brewers, or in fact most people do not use ice. Eventually you will be going to full boils, thus your ice route is useless, or you'll go to all grain once again useless.

Are your goals to make the best beer possible and learn ways to make the beer better? If so your ice method will not last long. A chiller can be made pretty cheap, or just purchased with no effort and will work great. Its hard to have sanitary ice, and it sure would suck to ruin a batch because of it.

Click to expand...

This is for extract brewers like me that don't have a chiller and need to get to the pitching temperature as fast as possible after boiling 2-3 gallons of wort. I've found that the ice guess work often misses the mark and forces the use of ice baths and long waits before the yeast can be pitched.
Like you say, if I had a chiller and/or went all grain I would not have this problem, but in the meantime I've found something that works for me and may help others.

ajosin said:

This is for extract brewers like me that don't have a chiller and need to get to the pitching temperature as fast as possible after boiling 2-3 gallons of wort. I've found that the ice guess work often misses the mark and forces the use of ice baths and long waits before the yeast can be pitched.
Like you say, if I had a chiller and/or went all grain I would not have this problem, but in the meantime I've found something that works for me and may help others.

Click to expand...

There is no "as fast as possible". There are people that do no chill brewing and in my opinion I think that is less risky than using ice. If you can sit it in a ice bath and stir and it take you 20 to 30 minutes or so, at least you are not directly added foreign material into the wort.

What I did when I was extract, was throw 3 gallons of still sealed jugs of water into the freezer and get them almost to freezing point. With that I did not have to chill the wort too much in the ice bath.

But whatever works for you, that's what brewing is about. But if you make a "why is my beer infected thread" and mention ice, everyone will jump on the bashing train.

rodisian said:

This is fantastic! I've try to do this in my head and have mixed results. Sometimes I'm spot on, but usually I end up with too much ice, or the ice isn't enough and I'm back to water baths (which I usually do as insurance(

Would definitely look forward to an online calculator/app, or even a table.

Thanks for your effort

Click to expand...

Rodisian, I made an applet for us (express cooling method). Let me know what you think (no more ice baths )

http://tinyurl.com/4ysv8qb

Well I applaud your efforts! Without quantitative data beer would just be a lot of guessing. I'm no math expert, but after taking a statistics class in college I realized just how important numbers can be.

I did the ice bath thing for a few batches. I quickly summized that it sucks donkey balls. It takes way too long. I never had enough ice on hand. And not to mention the longer it takes to get the wort into a fermentor the more chance you have of introducing an infection.

ajosin said:

Ok, here is a table that may help. It assumes that you have frozen 1.5 gallons of water to Ti= -2F (typical of freezers) and that your tap water temperature is Tw = 60F (typical of tap water). To achieve an pitching temperature of 72.5F, you need to wait for the boiled volume of wort (x gallons) to cool down to the following temperature before mixing it with ice and tap water,

x(g) Tx(F)
---------
2.0 Not enough boiled wort!
2.1 Not enough boiled wort!
2.2 Not enough boiled wort!
2.3 212 (no need to wait!)
2.4 206
2.5 200
2.6 195
2.7 190
2.8 185
2.9 181
3.0 177

Again, same calculation as above but using 1 gallons of frozen water (instead of 1.5),

x(g) Tx(F)
---------
2.0 188
2.1 182
2.2 176
2.3 171
2.4 166
2.5 162
2.6 158
2.7 155
2.8 151
2.9 148
3.0 145

You can see it is less risky to use 1 gallon of frozen water (since there is little risk of over-cooling), but you'll need to wait more.

For the general situation I would have to write an app. I can write a java applet for that and put it on-line at a later date.

Click to expand...

Won't the S.G. of the wort make a difference? Higher S.G. = denser = more mass (in the same volume) to cool => more ice.

So most of you guys pre-boil your top up water?

I always thought/heard/read that straight up tap water, so long as your tap water is good, is fine for your top up water.

That's all I've ever used when doing concentrated wort boils and everything has always turned out fine.

Well, let me offer something kind of different. I'm not an expert at all, but have been brewing a few years and I usually "get it right".

I'm an AG brewer. My main point here is that I am much more worried about contamination than I am about the old adage "cool it as fast as possible". I think it is more important to reduce chances of contamination and pitch yeast at the appropriate temperature than to worry about speed. What I do is move the boil kettle to an ice bath, insert my chiller and continually stir the wort. It takes 10 minutes or so to get it to about 80 degrees (perhaps a bit more). At that time, I rack it to my carboy and put the carboy in my "fermentation place" - which is a wine cooler set for 64 degrees. It takes about 3 hours for it to chill down, then I shake the crap out of it, pitch the starter (in my case) and shake the crap out of it again.

I would love to have a better facility, such as a kegerator or freezer set for 40 degrees or so (in fact, I have my eye on a brew that requires a week of cold fermentation), but this works really well for me. I'm not disputing the experts that harp on doing it FAST, but just saying that, for me, this has resulted in excellent products.

ajosin said:

Just noticed that it only takes you 15 minutes to cool boiling wort to 65F! That it really that fast, it takes me a lot longer... (How do you do it?)

Click to expand...

I put the pot in a sink full of ice water, and gently stir the wort as well as the ice water bath. When the ice all melts, I add more. It doesn't take long at all.

Dons said:

Well, let me offer something kind of different. I'm not an expert at all, but have been brewing a few years and I usually "get it right".

I'm an AG brewer. My main point here is that I am much more worried about contamination than I am about the old adage "cool it as fast as possible". I think it is more important to reduce chances of contamination and pitch yeast at the appropriate temperature than to worry about speed. What I do is move the boil kettle to an ice bath, insert my chiller and continually stir the wort. It takes 10 minutes or so to get it to about 80 degrees (perhaps a bit more). At that time, I rack it to my carboy and put the carboy in my "fermentation place" - which is a wine cooler set for 64 degrees. It takes about 3 hours for it to chill down, then I shake the crap out of it, pitch the starter (in my case) and shake the crap out of it again.

I would love to have a better facility, such as a kegerator or freezer set for 40 degrees or so (in fact, I have my eye on a brew that requires a week of cold fermentation), but this works really well for me. I'm not disputing the experts that harp on doing it FAST, but just saying that, for me, this has resulted in excellent products.

Click to expand...

I just noticed that you're in Carabelle. We were down there last winter (2010) looking for a place to rent long term in the winter. I found a place on the river, but we decided on Texas. I noticed that area of the panhandle is a beer wasteland- and not even a good bar! I did like the coffee shop though.

If your method works, that's great. I am lucky, because my tap water is usually 45 degrees, so it makes a chiller very effective!

Dons said:

Well, let me offer something kind of different. I'm not an expert at all, but have been brewing a few years and I usually "get it right".

I'm an AG brewer. My main point here is that I am much more worried about contamination than I am about the old adage "cool it as fast as possible". I think it is more important to reduce chances of contamination and pitch yeast at the appropriate temperature than to worry about speed. What I do is move the boil kettle to an ice bath, insert my chiller and continually stir the wort. It takes 10 minutes or so to get it to about 80 degrees (perhaps a bit more). At that time, I rack it to my carboy and put the carboy in my "fermentation place" - which is a wine cooler set for 64 degrees. It takes about 3 hours for it to chill down, then I shake the crap out of it, pitch the starter (in my case) and shake the crap out of it again.

I would love to have a better facility, such as a kegerator or freezer set for 40 degrees or so (in fact, I have my eye on a brew that requires a week of cold fermentation), but this works really well for me. I'm not disputing the experts that harp on doing it FAST, but just saying that, for me, this has resulted in excellent products.

Click to expand...

I've read about doing this, but I heard you're better off putting the cooling wort into an ice bath or a tub full of colder water, as it is more efficient than cool air circulating around in a fridge or keezer. However, if time isn't a factor for you, I'm sure a fridge would work fine. For my last batch, I got my wort down to 80, and I was using Nottingham yeast. As a result, I was looking for ways to get my wort down to about high 60's ASAP, since I already rehydrated my yeast (I won't make this mistake of rehydrating the dry yeast until I'm almost at my correct pitching temp). It took about 30 minutes in a tub full of cold water to bring the temp down to about 70. And remember, this is after I already had my ice bath to get the wort down to 80. I really need to find a better way of cooling my wort to proper pitching temps. Had I not already rehydrated my yeast, I probably would've left my wort in a fridge for a few hours to cool to the ideal pitching temp.

Since you said you do this now, are there any concerns with cooling your wort this way? I have a perfectly good unused fridge that I can use for this next time, but I get nervous leaving my wort unattended for a few hours before I pitch my yeast.

Maxkling said:

Your just running in circles, there are reasons why seasoned brewers, or in fact most people do not use ice. Eventually you will be going to full boils, thus your ice route is useless, or you'll go to all grain once again useless.

Are your goals to make the best beer possible and learn ways to make the beer better? If so your ice method will not last long. A chiller can be made pretty cheap, or just purchased with no effort and will work great. Its hard to have sanitary ice, and it sure would suck to ruin a batch because of it.

Click to expand...

Does doing a full boil really add anything? I know it affects your hop utilization and your color, but both those things can be accounted for if you're using brewing software. I currently do 3 gallon boils for ease. When you're doing an AG batch is your wort volume always your batch volume?

82cabby said:

Won't the S.G. of the wort make a difference? Higher S.G. = denser = more mass (in the same volume) to cool => more ice.

Click to expand...

Yes it does, but since the error is onl 5% (~3 F @ 75F) it is ignored.
The other source of error is the heat that is given to the environment after the boiled wort/ice/water mix is made; this will make the final mix cooler than expected (fortunately it is in the opposite direction of the S.G effect).
In the end I ignore both since they I do not know how to include them in the calculation and they go in opposite directions.

CanadianQuaffer said:

So most of you guys pre-boil your top up water?

I always thought/heard/read that straight up tap water, so long as your tap water is good, is fine for your top up water.

That's all I've ever used when doing concentrated wort boils and everything has always turned out fine.

Click to expand...

I use tap water for the ice and top-off. No issues so far. I do put the ice in sterilzed cover tuperware, but that is it.

BrewMeThatBeer said:

Does doing a full boil really add anything? I know it affects your hop utilization and your color, but both those things can be accounted for if you're using brewing software. I currently do 3 gallon boils for ease. When you're doing an AG batch is your wort volume always your batch volume?

Click to expand...

I cant answer as I never did a full boil extract, but have heard that it greatly increases the quality of the beer, but I cant swear on it. You can easily find the answer by searching though.

With all grain, after my sparge I have roughly a gallon more in the boil kettle. My set up boils off about a gallon an hour. So your preboil gravity will be lower than your post boil (OG), after the boil off you should be at your target OG depending on your efficiency and if you adjusted your recipe for your average efficiency.

So my wort volume after the boil is my batch volume.

Maxkling said:

I cant answer as I never did a full boil extract, but have heard that it greatly increases the quality of the beer, but I cant swear on it. You can easily find the answer by searching though.

Click to expand...

It definitely does! When trying to decide on boil size, my advice is always "Boil as much of the entire batch as you can!" You'll have less "extract-y" tasting wort, better hops utilization, lighter colored finished beer, and a beer that tastes more like an all-grain batch.

kyle6286 said:

I've read about doing this, but I heard you're better off putting the cooling wort into an ice bath or a tub full of colder water, as it is more efficient than cool air circulating around in a fridge or keezer. However, if time isn't a factor for you, I'm sure a fridge would work fine. For my last batch, I got my wort down to 80, and I was using Nottingham yeast. As a result, I was looking for ways to get my wort down to about high 60's ASAP, since I already rehydrated my yeast (I won't make this mistake of rehydrating the dry yeast until I'm almost at my correct pitching temp). It took about 30 minutes in a tub full of cold water to bring the temp down to about 70. And remember, this is after I already had my ice bath to get the wort down to 80. I really need to find a better way of cooling my wort to proper pitching temps. Had I not already rehydrated my yeast, I probably would've left my wort in a fridge for a few hours to cool to the ideal pitching temp.

Since you said you do this now, are there any concerns with cooling your wort this way? I have a perfectly good unused fridge that I can use for this next time, but I get nervous leaving my wort unattended for a few hours before I pitch my yeast.

Click to expand...

Well, I'll let others smarter than I answer any concerns, but as I said, this is working well for me. I use liquid yeast with a starter, so I put the starter in the same cooler as the wort. They are then the exact same temp. I aim for 65f.

Yooper said:

It definitely does! When trying to decide on boil size, my advice is always "Boil as much of the entire batch as you can!" You'll have less "extract-y" tasting wort, better hops utilization, lighter colored finished beer, and a beer that tastes more like an all-grain batch.

Click to expand...

Well there you go, question answered.