Brew Tips #13: Boil Length
The more I research brewing and craft brewing, the more I discover that a lot of practices and concerns stem from commercial breweries and rarely, if ever, apply in the home brewing world. To some degree boil duration is a part of that. I've seen many posts on forums saying that once you go all grain you should always be doing a 90 minute boil and when it isn't 90 minutes it is always 60 as the only other alternative.
So, how long a boil is required? Well, that is actually a not so easy answer, and the two biggest reasons are that one is dependent on your ability to chill your wort and the other is regarding hops additions.
Chances are (if you're reading THIS blog) that you're not doing massive batches. I'm talking commercially large. Or even 10 gallon batches. So, for most of us your ability to chill your wort is probably not really that large of a factor.
This is considered a factor because once your wort drops below boiling, steam isn't carrying away DMS anymore, but it is still at temperatures which produce it until it get below a certain temperature (I can't remember, around 160 or 180F). This may make your beer taste astringent and the longer you boil the fewer constituent components remains that can produce DMS that will stay in your beer.
You can boil longer than 90 minutes, but by that point you've really past the point of diminishing returns and the threat is already largely subdued. As a result, I haven't really seen anyone ever suggest a 2 hour boil or more (though I'm sure such people exist).
In practice, you're not likely to ever completely eliminate DMS in beer. But, below a certain threshold, the smell and taste are over powered by other flavors and smells in your beer. Even if you have a very light beer.
I bring up commercial breweries, but when you're dealing with triple digit (or more) gallons of beer, truly getting all of it, or ever just the majority below those temperatures in a reasonable timeframe is typically not viable. Many employ processes which drain the beer through cooling tanks, but, it is only the beer which passes through that cools quickly. Beer still in the kettle waiting to drain can remain near boiling for much longer periods of time than what even the most ghetto home brewers experience.
Almost as if to drive this point home is the fact that the "no chill" method even exists and is widely used anywhere. If DMS production were a serious threat on home brew batch sizes NO ONE would EVER continue to use the "no chill" method. Which is effectively a double whammy of DMS because it not only involves exerting NO EFFORT to chill the wort, it also involves letting it come down to pitching temperatures in an air tight container where the DMS has nowhere to go but BACK INTO YOUR BEER. Sorry for the caps. But these points really needed to be stressed. I have no doubts at all that the no chill method results in more DMS. And I wouldn't be surprised that if you do two identical batches, one with and one without the no chill method, that you could probably pick out the no chill method batch.
The point is more that, even with such extreme negligence on the cooling front you can still make a perfectly drinkable beer. So just about any active cooling attempt on a home brew scale is likely to result in a beer with non-detectable levels of DMS.
That all having been said. If you have a particularly shitty cooling system AND you wish to drop the boil time (especially below 60 minutes) then you really are tempting fate. Choose your battles.
But, cooling isn't the only consideration. The longer hops are boiled the more bitterness they contribute. Also, many state that the way the bitterness is perceived is also different based on boil time. So, if you have a great cooling system and wanted to cut your brew day down to just a 20-30 minute boil you might find that you A) need to buy nearly double the hops and B) that even with the same IBU's the flavor isn't the same.
I think this is partly where the 60 minute recommendation comes into play. Around that mark, I believe that you start seeing diminishing returns on IBU's and there isn't really a ton of information on the effect on the taste for a 60 minute addition vs, say a 90 or 120 minute addition. At least, not that I can find.
So, the 60 minute mark seems like a nice trade off to me. You don't boil off as much DMS as with 90 minutes or more, but you still get rid of the bulk of it (probably enough to ensure it doesn't cause you any problems) and save yourself some time. In addition, you boil long enough to get good hop utilization rates so you aren't dealing with massive quantities of hops in the bottom of the kettle at the end of the boil.
Where that leaves me is, if I were to try the no chill method, I would probably opt for the 90 minute boil. But I hear many people are fine with 60 there as well.
Usually I go for 60 minutes both because I like to keep my hops low enough that I'm not losing more beer than I need too before I even get it fermenting and because my cooling method is a bath tub of water which can take 30 minutes to an hour before reaching pitching temps.
Quick note, 30-60 minutes of cooling may sound bad. But the laws of thermodynamics are on my side. Temperature drops most rapidly the wider the margin from the ambient cooling temperature. If I'm not topping up with cold water at the end, the extra half hour is really just to take it from 30C to ~20C. The wort is probably below DMS production temperatures in as little 15 minutes if not less.
On a related side note: This method (for these reasons), can actually be more efficient for getting the whole of the wort below those temperatures than a counter flow chiller or heat exchanger. In fact, I've seen many people go from a CFC or heat exchange plates BACK to immersion chillers for this very reason (well, also because they suck to clean and sanitize). Bath tubs and immersion chillers are both in contact with more of the wort at any given time, and the chilled wort remaining is being chilled by the wort in contact with your chiller. And the result is that while a CFC or a good heat exchanger might get you to pitching temperatures faster, it will, more likely get you below 160F more slowly.
So there you have it. If you have a great chilling solution and no need for 60 minute additions, you could probably shave some time off of your boil. I would start small (5-10 minute intervals) and see if you notice differences before making a major jump. And of course, you want to go at least 10-15 minutes regardless of DMS to sanitize the wort.
So, how long a boil is required? Well, that is actually a not so easy answer, and the two biggest reasons are that one is dependent on your ability to chill your wort and the other is regarding hops additions.
Chances are (if you're reading THIS blog) that you're not doing massive batches. I'm talking commercially large. Or even 10 gallon batches. So, for most of us your ability to chill your wort is probably not really that large of a factor.
This is considered a factor because once your wort drops below boiling, steam isn't carrying away DMS anymore, but it is still at temperatures which produce it until it get below a certain temperature (I can't remember, around 160 or 180F). This may make your beer taste astringent and the longer you boil the fewer constituent components remains that can produce DMS that will stay in your beer.
You can boil longer than 90 minutes, but by that point you've really past the point of diminishing returns and the threat is already largely subdued. As a result, I haven't really seen anyone ever suggest a 2 hour boil or more (though I'm sure such people exist).
In practice, you're not likely to ever completely eliminate DMS in beer. But, below a certain threshold, the smell and taste are over powered by other flavors and smells in your beer. Even if you have a very light beer.
I bring up commercial breweries, but when you're dealing with triple digit (or more) gallons of beer, truly getting all of it, or ever just the majority below those temperatures in a reasonable timeframe is typically not viable. Many employ processes which drain the beer through cooling tanks, but, it is only the beer which passes through that cools quickly. Beer still in the kettle waiting to drain can remain near boiling for much longer periods of time than what even the most ghetto home brewers experience.
Almost as if to drive this point home is the fact that the "no chill" method even exists and is widely used anywhere. If DMS production were a serious threat on home brew batch sizes NO ONE would EVER continue to use the "no chill" method. Which is effectively a double whammy of DMS because it not only involves exerting NO EFFORT to chill the wort, it also involves letting it come down to pitching temperatures in an air tight container where the DMS has nowhere to go but BACK INTO YOUR BEER. Sorry for the caps. But these points really needed to be stressed. I have no doubts at all that the no chill method results in more DMS. And I wouldn't be surprised that if you do two identical batches, one with and one without the no chill method, that you could probably pick out the no chill method batch.
The point is more that, even with such extreme negligence on the cooling front you can still make a perfectly drinkable beer. So just about any active cooling attempt on a home brew scale is likely to result in a beer with non-detectable levels of DMS.
That all having been said. If you have a particularly shitty cooling system AND you wish to drop the boil time (especially below 60 minutes) then you really are tempting fate. Choose your battles.
But, cooling isn't the only consideration. The longer hops are boiled the more bitterness they contribute. Also, many state that the way the bitterness is perceived is also different based on boil time. So, if you have a great cooling system and wanted to cut your brew day down to just a 20-30 minute boil you might find that you A) need to buy nearly double the hops and B) that even with the same IBU's the flavor isn't the same.
I think this is partly where the 60 minute recommendation comes into play. Around that mark, I believe that you start seeing diminishing returns on IBU's and there isn't really a ton of information on the effect on the taste for a 60 minute addition vs, say a 90 or 120 minute addition. At least, not that I can find.
So, the 60 minute mark seems like a nice trade off to me. You don't boil off as much DMS as with 90 minutes or more, but you still get rid of the bulk of it (probably enough to ensure it doesn't cause you any problems) and save yourself some time. In addition, you boil long enough to get good hop utilization rates so you aren't dealing with massive quantities of hops in the bottom of the kettle at the end of the boil.
Where that leaves me is, if I were to try the no chill method, I would probably opt for the 90 minute boil. But I hear many people are fine with 60 there as well.
Usually I go for 60 minutes both because I like to keep my hops low enough that I'm not losing more beer than I need too before I even get it fermenting and because my cooling method is a bath tub of water which can take 30 minutes to an hour before reaching pitching temps.
Quick note, 30-60 minutes of cooling may sound bad. But the laws of thermodynamics are on my side. Temperature drops most rapidly the wider the margin from the ambient cooling temperature. If I'm not topping up with cold water at the end, the extra half hour is really just to take it from 30C to ~20C. The wort is probably below DMS production temperatures in as little 15 minutes if not less.
On a related side note: This method (for these reasons), can actually be more efficient for getting the whole of the wort below those temperatures than a counter flow chiller or heat exchanger. In fact, I've seen many people go from a CFC or heat exchange plates BACK to immersion chillers for this very reason (well, also because they suck to clean and sanitize). Bath tubs and immersion chillers are both in contact with more of the wort at any given time, and the chilled wort remaining is being chilled by the wort in contact with your chiller. And the result is that while a CFC or a good heat exchanger might get you to pitching temperatures faster, it will, more likely get you below 160F more slowly.
So there you have it. If you have a great chilling solution and no need for 60 minute additions, you could probably shave some time off of your boil. I would start small (5-10 minute intervals) and see if you notice differences before making a major jump. And of course, you want to go at least 10-15 minutes regardless of DMS to sanitize the wort.
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