How Important is length of Mash? - Home Brew Forums
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Old 04-21-2013, 07:25 PM   #1
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Been wondering and haven't found a whole lot of good research but how much time is really need for conversion for a typical Mash....my Mash tun recently has really been dramatically dropping temps after 30 minutes going from 150 to 140 very quickly...but haven't notice any change in efficiency and final product has been great

What I want to know is there research on how much time you really need to convert at optimal temps?


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Old 04-21-2013, 07:26 PM   #2
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I use an insulated keggle with a false bottom for reference


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Old 04-21-2013, 07:55 PM   #3
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You can use iodine to tell if you have any starch left. Just collect a sample (a drop or 2) of your wort, put it on something like a white plate so you can see color changes and add a drop of iodine next to it. Use a toothpick to mix the two. If it turns blue, there is still starch. If the iodine stays reddish, there is no starch left.

Your enzymes work over a range of temperatures so you get conversion from alpha amylase and beta amylase as it cools. Starting at 150 would get you a pretty dry beer and as the temperature goes down, the beta amylase has more effect and will make the wort more fermentable. If you start at a higher temperature the wort will be less fermentable because beta amylase is denatured at the higher temperatures. Your efficiency won't change but the fermentability of the wort will.

I'd read that the enzymes work quickly but I couldn't find a definitive number of minutes or hours so I experimented by starting a batch with the intent of taking an immediate sample and then one every 5 minutes until I got no change in color with my iodine. I BIAB so my grains were ground fine. At mash in the sample turned dark blue, so there definitely was starch. I missed the 5 minute mark and grabbed the sample at 7 minutes. No change in color, so the enzymes reacted in less than 7 minutes.

With a coarser crush, you need to get the water to the center of the particles to get the conversion since the dry grain won't convert. That's where the 60 minute mash becomes necessary as you wait for the grains to get wet and leach the sugars back out.

 
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Old 04-21-2013, 08:01 PM   #4
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I have heard people mention conversion times of as low as 15 to 20 minutes, but I always go with 60 just to be safe. At lower temps (e.g. 148-149) it can take longer.

 
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Old 04-21-2013, 09:18 PM   #5
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Quote:
Originally Posted by RM-MN
You can use iodine to tell if you have any starch left. Just collect a sample (a drop or 2) of your wort, put it on something like a white plate so you can see color changes and add a drop of iodine next to it. Use a toothpick to mix the two. If it turns blue, there is still starch. If the iodine stays reddish, there is no starch left.

Your enzymes work over a range of temperatures so you get conversion from alpha amylase and beta amylase as it cools. Starting at 150 would get you a pretty dry beer and as the temperature goes down, the beta amylase has more effect and will make the wort more fermentable. If you start at a higher temperature the wort will be less fermentable because beta amylase is denatured at the higher temperatures. Your efficiency won't change but the fermentability of the wort will.

I'd read that the enzymes work quickly but I couldn't find a definitive number of minutes or hours so I experimented by starting a batch with the intent of taking an immediate sample and then one every 5 minutes until I got no change in color with my iodine. I BIAB so my grains were ground fine. At mash in the sample turned dark blue, so there definitely was starch. I missed the 5 minute mark and grabbed the sample at 7 minutes. No change in color, so the enzymes reacted in less than 7 minutes.

With a coarser crush, you need to get the water to the center of the particles to get the conversion since the dry grain won't convert. That's where the 60 minute mash becomes necessary as you wait for the grains to get wet and leach the sugars back out.
I'll have to try the iodine test and do some experimenting thanks for the info
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Old 04-21-2013, 09:18 PM   #6
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I do BIAB and go 45 minutes for mash then turn up the heat for mash out. With my fine crush I think I could probably cut that time down to 30 min or less if I checked with iodine but I wonder how accurate the iodine test really is?

 
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Old 04-21-2013, 09:20 PM   #7
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Quote:
Originally Posted by bumstigedy
I have heard people mention conversion times of as low as 15 to 20 minutes, but I always go with 60 just to be safe. At lower temps (e.g. 148-149) it can take longer.
That its kind of what I've seen in my research but no real numbers to back that up though....my theory is 20 minutes is enough time but ill have to test and report back...going to see if anyone in my brew club wants to try to test too to get a larger sample
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Old 04-21-2013, 09:33 PM   #8
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Havent tried iodine tests, but ive heard they only check for if conversion has started yet, but not the extent of how much conversion has actually taken place. So you potentially have an iodine test say conversion has started, but you could still have some unconverted starches in there. Any truth to this?

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Old 04-21-2013, 10:54 PM   #9
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Iodine is testing for starch in suspension. It's doesn't tell you if you got all the starch out of the grains in the first place.

 
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Old 04-21-2013, 11:01 PM   #10
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Kai Troester has the answers. That guy is great. For those averse to reading the data, 2 additional hours of mash time will earn you about 4% more attenuation in the beer.

http://braukaiser.com/wiki/index.php...Fermentability


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