Boiling Time

[scottjk7890]

Anyone know how long a boil actually needs to be to boil off volatiles? I've tried to have this discussion with my boss but he insists on a 90 minute boil time for that reason, and then our conversation ends. If you know of a source I can find for evidence it would be appreciated. Thanks.

[Jedi]

Anyone know how long a boil actually needs to be to boil off volatiles? I've tried to have this discussion with my boss but he insists on a 90 minute boil time for that reason, and then our conversation ends. If you know of a source I can find for evidence it would be appreciated. Thanks.

You are asking a wierd question. Conversion is mash, Boil is a reduction of water to increase gravity and boil off tannins, etc.

[jebzter]

It depends on the boiling system in use, and the types of grain. Boiling accomplishes many things, not just a gravity increase, but reduction in DMS, isomerization, floculation of protein/tannin complexes, and various other reactions. You can tell him that 60 minutes on our 10bbl direct fired system is adequate for most malts to get rid of DMS, anything more than 20% pils malt and I up it to 90 minutes. Other systems are able to accomplish this in less time, though they are much more expensive and only found on much larger systems from Krones, Steineker, etc. There is some merit to doing a 90 min boil and not adding hops until 20-30 min have passed, this helps with reducing tannin levels from the grain, useful if you are having chill haze issues.

[Junkyard]

If you are boiling "hard", 60 min will work fine under all circumstances. By hard I mean that baby is rolling.

[TheCarolinian]

It depends on the boiling system in use, and the types of grain. Boiling accomplishes many things, not just a gravity increase, but reduction in DMS, isomerization, floculation of protein/tannin complexes, and various other reactions. You can tell him that 60 minutes on our 10bbl direct fired system is adequate for most malts to get rid of DMS, anything more than 20% pils malt and I up it to 90 minutes. Other systems are able to accomplish this in less time, though they are much more expensive and only found on much larger systems from Krones, Steineker, etc. There is some merit to doing a 90 min boil and not adding hops until 20-30 min have passed, this helps with reducing tannin levels from the grain, useful if you are having chill haze issues.

I agree with this one based on information I have read in the MBAA Practical Hanbdbook series here: http://www.mbaa.com/store/Pages/519KIT.aspx If you're looking for sources specifically, try here. They are very in-depth but accessible. Volume 1 specifically deals with malts and hot side issues, but it's a better deal to get the package.

Jebzter, I've never heard that about the pils malt though. Did you learn that from your own experience, or did you learn that somewhere you can share with us? Any idea why pils is different?

[jebzter]

The processing for pils malt does not drive off the DMS as well as other malts. It is only an issue with standard kettle boiling, especially if a rolling boil is not achieved. The harder the boil, the faster it drives it out. Modern equipment uses thin film evaporators to do this and can get everything done in a fraction of the time.

[TheCarolinian]

The processing for pils malt does not drive off the DMS as well as other malts. It is only an issue with standard kettle boiling, especially if a rolling boil is not achieved. The harder the boil, the faster it drives it out. Modern equipment uses thin film evaporators to do this and can get everything done in a fraction of the time.

Thin Film Evaporator animation: https://youtu.be/jRieOgIKdMQ

Neat! Thanks!

[Bainbridge]

Yep. We boil things like our Kolsch and our Alt for 90 (lots of German pils and vienna), but there's really no reason to boil say a stout for that long. We switched our IPA to 60 minutes, which saved us an hour on double brewdays, and didn't notice a difference (except in things like boil-off % and so on, and easily accounted for.)

[jebzter]

Thin Film Evaporator animation: https://youtu.be/jRieOgIKdMQ

Neat! Thanks!

Check out the Merlin system that New Belgium uses. The animation you have is not something that is used in a brewery, but it gets the point across about how they work. Internal calandria boilers with the china hat do similar things, not as efficient, but does a good job increasing surface area for evaporation.

[brewmaster 2011]

The more violent the boil the more volatiles are removed. Same goes with fermentation. All my beer have Weyermann Pilsner as the base malt. I make beers from German Pilsners to American IPA. I have yet to have any sulfur off flavors.

[dick murton]

Boil is a reduction of water to increase gravity and boil off tannins, etc.

Tannins do not boil off. DMS is boiled off, and DMS precursor is converted to DMS and then flashed off.

As other posts have mentioned, different malts have different levels of DMS and DMSP in them after malting - the paler lower temperature roast malts generally having higher level than say a pale ale malt. Depending on the source malt, you can leave in / create higher levels of DMSP depending on your mashing and sparging process, but particularly wort boiling process.

There is no simple answer to time. However, generally, a vigorous boil giving plenty of surface area for DMS and other undesirable volatiles evaporation - something around 4% evaporation and 60 minutes is typically quoted. The time and vigour will also affect the degree of protein coagulation and hence haze and flavour stability. 30 minutes is all you need for about 95% conversion of the alpha acids into iso alpha acids that you would achieve from a 60 minute boil. 90 minutes will not convert appreciably more than you get from a 60 minute boil

Because of the variability in boiling systems, you cannot say 90 minutes is essential, any more than 60 minutes or 45 minutes is essential. If you want to try reducing the boil time and save energy, then I suggest you aim for some trials, reducing the boil time by say 10 minutes per trial. Repeat a couple of times if the first trial appears successfully identical. Then reduce by a further 10 minutes, allowing for shelf life checks if you are bottling / canning - so it is a slow process to reduce evaporation / boil time if you want to do it methodically with little risk of change to the product

[Jedi]

Tannins do not boil off. DMS is boiled off, and DMS precursor is converted to DMS and then flashed off.

That's not what I have learned or heard contrary to regarding tannins.

Hot break is the interaction between polyphenols and protein byproducts that occurs during the boiling of the wort. Proteins and polyphenols are removed during lautering when their opposite charges attract. But there is a fair amount of protein and protein byproduct that does not have the proper interactive charges to react with the polyphenols.

This is where the boiling process comes into play. Boiling is a violent physical reaction. A tremendous amount of energy is released when water is boiled. Boiling the wort denatures the protein (changes its structure). A similar effect occurs when eggs are fried and meat is cooked.

This energy is unleashed on the proteins that were not taken up by polyphenols during the lautering and mashing. The boil causes the proteins to change their structure; what was inside might now be on the outside. As a result many proteins, once boiled, change their outside electrostatic charge. This change makes them susceptible to polyphenol interactions, and thus more tannin material and protein is removed in the boil. If the boil is not* vigorous enough, these clumps of protein and tannin tend to get large and form a scum on the top of the boiling wort. If the boil is vigorous, which it should be for many reasons, then this top layer breaks into smaller particles.

[ChesterBrew]

I'd imagine the draw from the kettle would be a factor too. We have a condensate stack and 6" inline fan that vents to the exterior of our building. We also open a door to provide make-up air to the BK (3bbl system, 145 gal. kettle.)

[jebzter]

The venting will have little to do with increasing your vaporization rate unless you are putting the whole vessel under vacuum, then the resistance to the vaporization goes down(like being at a higher altitude) or if it is plugged an pressure is allowed to build which would decrease the vaporization rate. The biggest thing is to make sure that none of the condensate makes it back to the kettle, it is full of DMS.

[dick murton]

Jedi

You are spot on with your description of polyphenol removal. The only thing that is different is your use of "boiling off", which to my mind is evaporation - as used for water (and DMS) evaporation, not precipitation. Since I have only ever heard of "boiling off" referring to evaporation, perhaps this is one of those differences in terminology from one side of the pond to the other.

Cheers