How does the addition of boiling water to a mash (infusion) not scorch the grains?

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Juno_Malone

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Hey all,

I don't have a ton of experience with infusion mashes; I've done them once or twice with mixed results. I'm planning on brewing a Czech pilsner this weekend with the following mash schedule:

Step 1: 146F for 35 minutes. 9.52 quarts strike 160F (1.12 qt/lb using 8.5# grain).
Step 2: 158F for 35 minutes. Adding 2.8 quarts boiling water (1.44 qt/lb).
Step 3: 168F for 10 minutes. Adding 3.2 quarts boiling water. (1.83 qt/lb).

It looks like this will start as a pretty thick mash (1.12 qt/lb) and end up pretty thin (1.83 qt/lb), but I guess that's unavoidable(?) with infusion mash. I'll also be doing a batch sparge at the end to hit my pre-boil volume of 7.2gal.

Anyway, my question is - how does the addition of boiling water not scorch the grains it initially touches? I guess the temperature equalizes pretty quickly, especially if you are constantly stirring while adding the boiling water. But it seems like all of the grains it initially touches would be scorched/their proteins denatured. Is this not something I need to worry about?

Thanks!
 

homebrewer_99

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Scorch, is not really the term that is relative here, but I understand where you're coming from.

IMO, they are not impacted because they are already over 140F. A 70 degree temperature difference is not substantial enough to scorch. I would think adding the first water to the grain is a far greater temperature range. Even with that, going from room temp to 160F, the grain and the tun reduces the temp about 10-13 degrees (depending on the amount of grain and volume of water used).

I use near boiling (200F) for batch sparging and it only raises the mash temp less than 25 degrees.

I wouldn't worry about something everyone does with success. :yes:
 

beernutz

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Brewers have been doing decoction mashes where part of the mash is removed and separately boiled for hundreds of years without scorching the grain. I think you'll be ok.
 

MaxStout

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The boiling water will only contact a small portion of the grains before it cools and reaches an equilibrium point with the rest of the mash.
 
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Juno_Malone

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Cool, thanks for the replies! As a follow-up, do I need to worry about my mash being so thick (1.12 qt/lb) at the start and so thin (1.83 qt/lb) by the end? Or is that just the nature of infusion mashes.
 

ancientmariner52

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To add to what has been said before, I believe there is a time factor involved. Chemical changes require time, and so does heat transfer. The added hot water will quickly lose it's heat to the cooler grain and water, before much denaturing of enzymes can occur, especially if you stir.

As to diluting the mash, many brewers do a full volume mash, with no sparge at all. They seem to be happy with the result.

Keep on questioning things, that's the only way we advance!
 

RM-MN

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You really are worried about denaturing the enzymes with the hot water as the hot water cannot scorch the grain. Most base malts contain far more enzymes than are necessary for full conversion so if your boiling water denatures some of them it is no big deal. It also takes some time to fully denature the enzymes so a short contact with the boiling water won't immediately destroy them either.
 

homebrewer_99

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OK, here's something that will help. Cut and paste this into a WORD DOC and print it out for your quick reference board:

MASHING

THIN MASH:
2 qts of water per pound of grain
Slower conversion takes more time
More fermentable sugars
Produces a drier beer

THICK MASH:
Less than 1.25 qts per pound of grain
Faster conversion
Fewer fermentable sugars
Produces a maltier beer

LOW MASH TEMP: 140 - 150F, for a light body
HIGH MASH TEMP: 150 - 160F, for a maltier body

OPTIMUM TEMP for a BALANCE of the two: 149F.
 

RM-MN

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OK, here's something that will help. Cut and paste this into a WORD DOC and print it out for your quick reference board:

MASHING

THIN MASH:
2 qts of water per pound of grain
Slower conversion takes more time
More fermentable sugars
Produces a drier beer

THICK MASH:
Less than 1.25 qts per pound of grain
Faster conversion
Fewer fermentable sugars
Produces a maltier beer

LOW MASH TEMP: 140 - 150F, for a light body
HIGH MASH TEMP: 150 - 160F, for a maltier body

OPTIMUM TEMP for a BALANCE of the two: 149F.
I'm afraid you have some old information here. Thin mashes convert just as fast or faster than the thicker mashes. The speed of conversion depends on the time it tales to gelatinize the starches so the crush of the grain is the deciding factor, not the water to grain ratio. The fermetability of the wort depends on the temperature of the mash, not the water to grain ratio. I also will dispute your optimum mash temperature of 149 because based on this article your temperature would make a very thin beer. Read this article on Brewers Window and see where the ideal mash temperature range falls in the graph. https://missionarybrewer.wordpress....ers-window-what-temperature-should-i-mash-at/
 

mongoose33

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I'm afraid you have some old information here. Thin mashes convert just as fast or faster than the thicker mashes. The speed of conversion depends on the time it tales to gelatinize the starches so the crush of the grain is the deciding factor, not the water to grain ratio. The fermetability of the wort depends on the temperature of the mash, not the water to grain ratio. I also will dispute your optimum mash temperature of 149 because based on this article your temperature would make a very thin beer. Read this article on Brewers Window and see where the ideal mash temperature range falls in the graph. https://missionarybrewer.wordpress....ers-window-what-temperature-should-i-mash-at/
Let me extend just a bit. When I started doing BIAB, I had a pretty narrow gap on my mill: .020. I'd stir at 15- and 30-minutes into the mash, then take pH (at 15 minutes) and gravity samples.

Done this way on a beer I did in November:

.020 Gap:
15 minutes: 1.042
30 minutes: 1.047
60 minutes: 1.048

That's pretty fast! Somebody--I think it was you, RM--said they do longer times even though conversion is essentially done, as the flavors are better. I think that has merit, so I mash all the way to 60 minutes.

Fast forward a bit. Now I'm implementing Low Oxygen brewing techniques. Part of that is using a coarser crush. I bought a Monster Mill 3-roller mill, and the gap is set at .035. Much coarser than what I had with my Barley Crusher and the .020 gap.

Here's a recent beer--different recipe so the numbers are different--using those techniques:

.035 Gap:
15 minutes: 1.022
30 minutes: 1.028
60 minutes: 1.058

Yeah, the first time I saw numbers like this I nearly panicked, but followed the RDWHAHB rule of thumb. Why the difference? As you note above, it's in the size of the particles in the crush. It just takes longer to gelatinize the larger particles. It still gets there, it just takes time.
 

homebrewer_99

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I'm afraid you have some old information here. Thin mashes convert just as fast or faster than the thicker mashes. The speed of conversion depends on the time it tales to gelatinize the starches so the crush of the grain is the deciding factor, not the water to grain ratio. The fermetability of the wort depends on the temperature of the mash, not the water to grain ratio. I also will dispute your optimum mash temperature of 149 because based on this article your temperature would make a very thin beer. Read this article on Brewers Window and see where the ideal mash temperature range falls in the graph. https://missionarybrewer.wordpress....ers-window-what-temperature-should-i-mash-at/
I agree the crush is important. I do a pretty fine crush.

FWIW, the sources for this information are contained in the 30+ books of my brewing library from authors such as Papazian, Palmer, BYO (10 years of subscription), HBT, et al.

All I did was put all these bits and pieces of info onto a quick reference chart that I pinned to my corkboard.

The MOST important factor here is THEY WORK FOR ME, I BREW FOR ME.
 

ClaudiusB

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I'm afraid you have some old information here. /quote]
What about you?
I also will dispute your optimum mash temperature of 149 because based on this article your temperature would make a very thin beer.
Based on your graph at 67 °C .

Based on German brewing science "By the time the mash reaches 67 °C (153 °F), there is practically
no β-amylase activity".

Half-life of β-amylase at 62 °C approx. 18.5 min
at 64 °C 9.3 min
at 65 °C 4.7 min
at 70 °C 1.7 min
Your graph shows enzyme activity of 45% at 153 °F (79 °C), no time giving.

According to German brewing science this applies only for approx. 5 min, after 10 min the activity is around 20% of initial value.

BRAUWELT INTERNATIONAL 2016/VI
Authors: Dr. Bertram Sacher and Prof. Dr.
Thomas Becker, Chair of Brewing and Beverage
Technology, TUM; em. Prof. Dr. Ludwig
Narziß, TUM, Freising, Germany
 

RM-MN

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With a very finely milled grain i'm getting conversion in less than 2 minutes. Beta amylase does not seem to need to be stable for long if it converts that fast.
 

ba-brewer

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Brewers have been doing decoction mashes where part of the mash is removed and separately boiled for hundreds of years without scorching the grain. I think you'll be ok.
I have never done a decoction mash but I would say that technique looks to have the most potential to actually scorch the grain. I would also bet there have been people that have actually scorched their grain due to not paying attention when bringing the thick grain slurry up to a boil.
 
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