The boil

[prankster1590]

So im using directions from the ray daniels book which gives an estimate of an evaporation rate of 5%/60 min. So I wanna end up with 10.5 L of solution after a boil of 90 minutes. So approx. 7.5% should have been evaporated. This means that the starting volume should have been 11.35 L of solution.

So I did an experiment. I made a sugar solution of 1.050 end boiled it. I did not inserted a lot of energy because i used a small gas pit with medium heat almost.

I went dry after 90 minutes. Now im afraid to do the boil with 10 liters. Should i just do it?

During the experiment i did not use a closed system. It was open to the atmosfear. Should I use a closed system?

 

[RM-MN]

First question is why do you want to boil 90 minutes? 90% of the hop bitterness is achieved in 30 minutes, nearly all is there in 60.
Second question is how hard did you boil your solution. As long as a boil is achieved at first the rest of the boil time can be not much more than a simmer. It doesn't need to be a rolling boil.

Evaporation rate is never a percentage. It is a constant based on how much heat you apply. Reduce the heat, reduce the evaporation.

What you evaporate is only water. If you are boiling off too much you can add some back.

 

[prankster1590]

First question is why do you want to boil 90 minutes? 90% of the hop bitterness is achieved in 30 minutes, nearly all is there in 60.
Second question is how hard did you boil your solution. As long as a boil is achieved at first the rest of the boil time can be not much more than a simmer. It doesn't need to be a rolling boil.

Evaporation rate is never a percentage. It is a constant based on how much heat you apply. Reduce the heat, reduce the evaporation.

What you evaporate is only water. If you are boiling off too much you can add some back.

Im trying for a Pilsner and Pilsners are boiled longer. I wanna copy Heineken en Heineken boils for 90 minutes.

Isn't evaporation rate also dependant on the amount of sugar in the solution. It also takes energy. And I calculated my bitterness with Tinseth to be 23 IBU with tettnanger, Perle and Hersbruck. I think the longer boil helps with other tastes and may be helps increasing the clarity or something. I dont know.

But should I put a lid on the system?

 

[RM-MN]

Im trying for a Pilsner and Pilsners are boiled longer. I wanna copy Heineken en Heineken boils for 90 minutes.

Isn't evaporation rate also dependant on the amount of sugar in the solution. It also takes energy. And I calculated my bitterness with Tinseth to be 23 IBU with tettnanger, Perle and Hersbruck. I think the longer boil helps with other tastes and may be helps increasing the clarity or something. I dont know.

But should I put a lid on the system?

The justification for boiling a Pilsner malt for 90 minutes is to drive off DMS. Putting a lid on keeps this from happening as the DMS will condense on the lid and fall back into the wort. I don't use Pilsner malts but I was taught that pale malt needed a 60 minute boil for the same reason, to drive off the DMS. It's funny but I don't seem to have a problem with that using only a 30 minute boil. Perhaps the long boil was really needed for the commercial quantities and that information found its way into home brewing much as using a secondary was brought into home brewing. Perhaps someone with experience with shorter boils using Pilsner malts will weigh in on this.

 

[Coastalbrew]

Boil off rate is different for each system. What I would do is repeat your experiment with a known volume of water. Boil for 30 minutes at whatever boil biggie you plan to achieve with your beer. At the end of the 30 minutes take the pot off the heat let it cool to the original water temp and measure how much water you have left. Multiply the loses times 2 for a 60 minutes boil and times 3 for a 90 minute boil. Then you know how much water you will need to start your boil. There is also a good calculator on Brewers friend that will get you very close as well.
As for keeping the lid on, conventional wisdom says no, leave it off. But I just listened to an interesting discussion on Brulosophy that indicates this may be less significant than previously thought. Good luck .

Cheers!

 

[mongoose33]

Turn down the heat. There's a vast difference between a violent rolling boil, where much more of the heat energy applied is flashing to steam, and a gentle simmer. Kettle dimensions also affect this.

There was a time when conventional wisdom suggested that one needs a good rolling boil, in part to drive off DMS. Here's an example of that: https://beerandbrewing.com/off-flavor-of-the-week-dms/ Among other things, the advice is to "Boil with vigor."

Well, maybe. There's a precursor to DMS that exists in light malts call SMM (can't recall the name, it's long and involved). Heat breaks the SMM down into DMS, and that process is more or less continuous unless you boil a very long time. This is why, with a Pils or similar, you want to chill that wort quickly at the end of the boil, so you stop the SMM --> DMS train.

There also is an increasing sense among brewers that a too-vigorous boil can damage malt flavors. Many, as a result, are moving toward doing more of a simmar than a boil.

So--if I were to give you a suggestion on all this, it would be to do an hour-long boil at a gentle simmer, uncovered. I've read some stuff that suggests covering doesn't limit the elimination of DMS, all that steam is going SOMEWHERE whether covered or not, but IMO there's a better reason not to cover--it's a lot easier to control boilovers.

But all that said: seems like a lot of work just to reproduce Heineken....

 

[Bassman2003]

What are you using for heat?

The topic you are asking about refers to thermal load. This is the amount of thermal units you put into the wort to make it boil. Throw a ton a wattage at it and the thing will be volcanic. Throw a little and you will need a lid just keep a simmer going. In between these two extremes is your rate of evaporation.

I used to boil the snot out of my wort. It is sort of a manly thing or an over-do type of approach. The industry has determined that all of that heat is not needed and can be harmful to some malt flavor compounds. I was surprised at how little heat along with a partial lid is needed to get a 6% evaporation rate.

The best way is to brew a batch and measure pre-boil and post-boil volumes, take notice of your heat levels, figure out what your evaporation rate was then adjust for the next batch. Once you dial in your system you will never have to think about it again until you change systems.

 

[kh54s10]

Every pot configuration and heat source will have a different boil off rate. You can use the calculators as a start but you will want to know the boil off rate of your system. Many sources say the average is 3/4 gallon per hour. My burner sputters and could go out when low, so my boil off rate is 2 gallons per hour.......

I boil without a lid.

 

[Saunassa]

After the initial boil and hotbreak foam(?) has happened and foam is reduced I turn the heat down until I have a slow boil/simmer. Three reasons: it is easier to prevent boil overs, people have said flavor is better and I use way less propane.

 

[kh54s10]

After the initial boil and hotbreak foam(?) has happened and foam is reduced I turn the heat down until I have a slow boil/simmer. Three reasons: it is easier to prevent boil overs, people have said flavor is better and I use way less propane.

You don't turn the heat down BEFORE the hot break foam??? This is when you have to work to prevent boil overs. I heat high until the foam starts rising then turn it down. After the hot break I turn my burner low until it sputters then up a notch. That is still hotter than needed, hence my very high boil off rate.

 

[applescrap]

It's the legendary brew professor Dr. Bamforth who States repeatedly brew with vigor. I thought brulosophy had tested a simmer verse boil and found Participants were in fact able to tell a rolling boil from simmer. And they preferred the rolling boil. It may have been basic brewing. Boil temperature is different where we all live. In theory its possible that someone's simmer is the same temperature as my boil here in Colorado. 90 minute vigorous boil is what the brew professor at ucla mentioned above would Recommend So as long as you get your water rates right you Are certainly well on your way to making good beer. Water has to do with knowing your system and with some documenting of your brews you will get the hang of it. If you document well enough you could probably figure an exact boil off rate. Based on your test you have a good place to start! 2.6 g in 90 minutes seems like a lot to boil off?

 

[Bassman2003]

I would like to know what evaporation rate Dr. Bamforth is targeting. Because in the end, the evaporation rate determines the amount of heat needed per system. If one uses a partial lid you can get more boiling with less heat as well. "Vigor" is sort of a nebulous term. Imho "simmer" is very low, hardly boiling.

 

[Toxxyc]

Honestly, I'd rather boil to gravity rather than volume. Mash, measure gravity and then determine what your final volume has to be to hit your target OG, then boil until you hit that, using the correct amount of hops in proportion to the batch size. If your mash efficiency is low, boil shorter and just brew a smaller batch. Also, most hops isomerize at a lot lower than boiling, around 79°C or 175°F. No need for a constant, rolling boil.

EDIT: Oh yes, and DMS is less of an issue in modern malts, as I have it. They're not the malts from 20 years ago.

 

[kh54s10]

Honestly, I'd rather boil to gravity rather than volume. Mash, measure gravity and then determine what your final volume has to be to hit your target OG, then boil until you hit that, using the correct amount of hops in proportion to the batch size. If your mash efficiency is low, boil shorter and just brew a smaller batch. Also, most hops isomerize at a lot lower than boiling, around 79°C or 175°F. No need for a constant, rolling boil.

EDIT: Oh yes, and DMS is less of an issue in modern malts, as I have it. They're not the malts from 20 years ago.

90% of the time I don't have to worry about hitting my OG. I have things dialed in well enough that I hit my OG and volume pretty close. At least close enough that it is not worth messing with any additives or trying to calculate what volume or boil time that I need to make the small change.

But I do think that you will get quite a bit difference in hop utilization at boiling compared to if the wort only reached 175 degrees.

 

[Saunassa]

You don't turn the heat down BEFORE the hot break foam??? This is when you have to work to prevent boil overs. I heat high until the foam starts rising then turn it down. After the hot break I turn my burner low until it sputters then up a notch. That is still hotter than needed, hence my very high boil off rate.

Well as the foam starts I do adjust down a bit but it always seems to really start a hard rolling boil just after the break and as the foam disappears. Once boiling it takes less heat to maintain the slow boil. I think some believe the vigorous, geyser type boil is needed and I was one of these on the first few batches. I tend to evaporate 3/4 per gallon now versus the 5 quarts I did with the vigorous boil. Probably biased but the wort just seems to have better flavor with the slow boil method.

 

[GPNewBrew]

My two cents:

1. Boil off is determined by the ambient temperature, geometry of the boil vessel, and the heating medium and BTU output.
2. Many schools of thought on boil time; depends on malt type. You will have to decide for yourself what you prefer. Some will say only 30 minutes is needed, others 90, particularly for lighter Pilsner malts. The post above regarding the link between SMM and DMS is spot on; there was a good article about this in Zymurgy a couple months back - good read.