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Old 12-07-2010, 03:11 AM   #11
boomernintysix
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I believe your issue comes in the misconception of what optimized for brewing and biologically optimized.

Biologically Alpha Amylase has a HUGE range of stable temperature operation. It is active from basically 0C up to 90C, which makes it ideal in starch conversion in a wide range of organisms (including humans).

Now with brewing your balancing what enzymes are in your mash, their working temps, and what you want to do. For example while your mashing at say 130F you'll have a lot of things going on, alpha and beta amylase and upward range of the proteases. The proteases are actively breaking down all the proteins in the mash INCLUDING alpha and beta amylase so obviously this is not a good place to be for too long.

So Alpha Amylase is very optimized (optimized DOES NOT MEAN MINIMIZED) for what it does and is widely used, and that we should all be thankful for. I hope this helps

 
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Old 12-07-2010, 01:39 PM   #12
apeltes
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I agree that alpha amylase can certainly do its job at nearly any temperature. It's a very forgiving enzyme. But any enzyme has, within the range of temperatures within which it will work, a window within which it works best (fastest)... depending on temperature and pH. For human amylase, I'm willing to bet it works best at around 98F. For barley, it should be closer to the temperature it usually experiences during germination, which surely isn't 160F (where we mash). The only thing, then, that makes sense is that barley's amylase isn't working as fast as it can when it does it's job during germination. If that were the case, we would mash at around 70F or 80F, I guess.

 
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Old 12-07-2010, 04:08 PM   #13
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Quote:
Originally Posted by apeltes View Post
But any enzyme has, within the range of temperatures within which it will work, a window within which it works best (fastest)... depending on temperature and pH.
I completely agree. That window is around (actually a little bit higher then) room temp. The point I was trying to make is that optimized for brewing, the 154-156 range, is that way because of lack of other enzyme activity not the speed of which alpha amylase works.

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Originally Posted by apeltes View Post
For human amylase, I'm willing to bet it works best at around 98F. For barley, it should be closer to the temperature it usually experiences during germination.
Correct, but it doesn't mean it can't work at higher temps effectively.

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Originally Posted by apeltes View Post
The only thing, then, that makes sense is that barley's amylase isn't working as fast as it can when it does it's job during germination. If that were the case, we would mash at around 70F or 80F, I guess.
Your thinking of this backwards. It works slower at mash temps, but it still works fine and decently fast (remember an hour is a LONG time in enzyme world). The reason we mash high as apposed to room temp is to denature enzymes we don't want working and just lucky enough that alpha and beta amylase can withstand the temps. If it wasn't the case we would have to boil the extract then add our mash enzymes then boil it again (with hops). I hope I made myself a little more clear.

 
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Old 12-07-2010, 04:50 PM   #14
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It is a happy coincidence for us that it is this stable. The half lives of proteins varies immensely. Some are stable for only minutes in their native environment, others are stable for a very long time - like the chitin and the protein in shells. It depends on the structure of the protein.

Once could conduct a mash at 50 F. It would take several days to convert, and during that time, a host of microbes present on the grain would start chewing up the released sugars. This is actually probably what happened on the very first beers (probably more like 90 F though).

Germination is a HIGHLY coordinated process. The seedling will only break down starch to make sugars as fast as they can be utilized for growth. Lots of excess sugar around is an open invitation for hungry microbes. These seeds are living in the soil which is loaded with organisms that would love to get at the sugar for themselves.

As an example, super sweet corn seeds are a pain to germinate in the field. The seeds don't store starch, just simple sugars. One result is the seeds really shrink and shrivel - and crack. Put them unprotected in the soil and the microbe party light goes on. Very few seedlings will survive without a seed fungicide treatment.
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Old 12-07-2010, 04:55 PM   #15
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And, germination does in fact occur more rapidly in a warmer than room temp environment. Lots of pro's in Nurseries utilize heat mats for seed starting to increase yield.

 
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Old 12-07-2010, 06:06 PM   #16
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My confusion is probably based on the chart below (from: http://www.realbeer.com/jjpalmer/ch14.html ).

It shows each enzyme having a "range", so I assumed alpha amylase works poorly below 146F. Is that not the case?


 
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Old 12-07-2010, 06:35 PM   #17
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Quote:
Originally Posted by apeltes View Post
My confusion is probably based on the chart below (from: http://www.realbeer.com/jjpalmer/ch14.html ).

It shows each enzyme having a "range", so I assumed alpha amylase works poorly below 146F. Is that not the case?

These ranges are specific to beer production. Plain and simple.

For temp optima related to germination, look at malting processes. Floor temps etc... Those are most definitely NOT kept at 150*F+ but are monitored for optimal success.

 
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Old 12-07-2010, 06:48 PM   #18
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Again, the range is for practical brewing application. We can't take 3 days to mash at 90F for a couple reasons. First, you'd get lacto infection which is great if you like Berliner Weisse but... Second, you're under the gelatinization temp of barley so the yield would suck badly. The reason why the brewing optimum is in the range is based on both the gelatinization temp and the speed at which you get full starch conversion.
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Old 12-07-2010, 09:33 PM   #19
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Quote:
Germination is a HIGHLY coordinated process. The seedling will only break down starch to make sugars as fast as they can be utilized for growth. Lots of excess sugar around is an open invitation for hungry microbes. These seeds are living in the soil which is loaded with organisms that would love to get at the sugar for themselves.
Thumbs up on that. Plants have to adapt to biological and nonbiological stresses/threats by changes in gene expression only, they can't run away.

 
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Old 12-07-2010, 09:48 PM   #20
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I think the consensus is that barley amylase is well-adapted to operate at germination temperatures. Although it works at mash temperatures, it doesn't work as well... but that's fine. We want to convert at the top of the temperature range to suppress other enzymes and to prevent infection.
Fair summary?

Question: What would happen if malt were mashed at 80F? Would the amylase succeed in quickly converting the starch? Would something interfere, since mashing does not happen in a living seed/embryo? Is the enzyme too dilute once mixed with so much water?

 
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