Mash Conversion Experiment

[buckeyebrewer]

I talked with a local commercial brewer the other day and he was describing his mashing technique. He said that he rarely mashes longer than 30 minutes and one of his beers he only mashes for 12 minutes....yes 12 minutes. He said that the conversion is usually done within 30 minutes and there is no reason to waste our time mashing any longer than that. He comes from a respectable brewery from Columbus so I took his word for it. I brewed a batch of Goose Islands Sofie today and decided to track the conversion of my mash. I took a refractometer reading every 4 minutes for 1 hour. I stirred my mash right before I took each reading. Here is the grain bill:
9 lbs Breiss Pilsner Malt
1 lb Breiss White Wheat Malt

Here are the results.
0 Minutes - 1.000
4 Minutes - 1.022
8 Minutes - 1.055
12 Minutes - 1.064
16 Minutes - 1.073
20 Minutes - 1.075
24 Minutes - 1.077
30 Minutes - 1.081
34 Minutes - 1.082
42 Minutes - 1.086
46 Minutes - 1.087
50 Minutes - 1.087
54 Minutes - 1.089
60 Minutes - 1.089
First of all I was really surprised that after only 12 minutes I was at 1.064...that is a pretty fast conversion. I'm wondering if I should have kept going past 60 minutes to see if it plateaued at 1.089. According to brewing software I hit my numbers exactly according to volume and grain bill at 80% efficiency. Now my question is why a professional brewer would choose to stop mashing at 12 minutes. Do certain grains convert faster than others. It's always been a 60 minute rule but I've never questioned the rule. I wonder if he adds more grain to just get more sugar from his first draining. Is it a time is money thing? I can't imagine 48 minutes is worth 25 points of gravity....any ideas?

 

[devilishprune]

Interesting experiment there. What temperature did you mash at? I guess unless you do RIMS or HERMs then you opening up the tun would affect your temperature. You may have had almost 1.089 at 30 minutes if not for that.

 

[buckeyebrewer]

I guess I should have included that as well. I have a RIMS system and mashed at 153. The temps were right on the whole time.

 

[buckeyebrewer]

Hey that was my 400th post....I was expecting balloons to fall from my ceiling.

 

[bob1852]

That's some interesting data....

I took the liberty of comparing it to % of total conversion...

25% 4 minutes
62% 8 minutes
72% 12 minutes
82% 16 minutes
84% 20 minutes
87% 24 minutes
91% 30 minutes
92% 34 minutes
97% 42 minutes
98% 46 minutes
98% 50 minutes
100% 54 minutes
100% 60 minutes

I guess if you wanted to speed up your brewday, you could do a 16-minute mash and just compensate to get whatever OG you need....

 

[buckeyebrewer]

That's a cool way of looking at it....it is amazing how fast it converts. I always noticed that a few minutes after I would mash in my fingers would be sticky with sugar but I never thought it would go this fast.

 

[buckeyebrewer]

Somebody help me out...how much more grain would you need to add to get the same amount of sugar in a 12 minute mash? If you mashed out at the 12 minute mark. This is like a 10th grade word problem.

 

[RM-MN]

How fine of a crush did you have? I'm under the impression that the finer the crush, the faster the conversion.

 

[bob1852]

Somebody help me out...how much more grain would you need to add to get the same amount of sugar in a 12 minute mash? If you mashed out at the 12 minute mark. This is like a 10th grade word problem.

So you're wanting to pick up 25 points so at 12 minutes your G is 1.089?

hmm.....

I'm sure it's a simple equation, but I can't think of it right now...

 

[buckeyebrewer]

It is a Schmidling Malt Mill....it comes from the factory preset at .045 inches. It makes a perfect crush on Breiss malt. I found that Muntons malt has a lager kernel and it tends to have more dust when crushing....I try to use Briess if possible.

 

[jkarp]

Somebody help me out...how much more grain would you need to add to get the same amount of sugar in a 12 minute mash? If you mashed out at the 12 minute mark. This is like a 10th grade word problem.

Problem is, based on the data, with a 12 minute mash, you'll have 72% converted sugars and 28% un-converted starches which you don't want in your beer. Shame you didn't do an iodine test along with your refrac readings.

 

[bob1852]

Problem is, based on the data, with a 12 minute mash, you'll have 72% converted sugars and 28% un-converted starches which you don't want in your beer. Shame you didn't do an iodine test along with your refrac readings.

hmmm.. but how many of those un-converted starches are still locked up in the grain and not in the wort?

 

[buckeyebrewer]

Doing a mash out would stop that wouldn't it? Would the unconverted starches rinse into the wort? I've had the so called 12 minute mash beer....you can't tell. I doesn't have any weird off flavors or anything funky going on.

 

[jkarp]

Here's Kai's work on the subject.

 

[buckeyebrewer]

So I'm still confused on how this guy can make 12 minute mashed beers and have them turn out fine if unconverted starches are making their way into the wort.

 

[BOBTHEukBREWER]

Maybe you run off the liquor at 12 minutes and hold the temperature of the run off for another 12 minutes at 157 deg F - ensuring any starches in the run off are converted.

 

[Northcalais40]

Have you considered the proportion of alpha to beta amylase at work over a short period of time. I would want to know that I am going to have a dry beer if I want one. I don't really know about this, but I would suppose that the beta amylase would be favored in a 16 minute mash.

This neglects a lot of variables, such as grind, stirring and water composition. Also, and I apologize if I am being overly critical, one experiment does not make science, it makes an event. Many repeatable experiments can point to facts.

That said I usually waste 45 min on decoctions anyway, so that puts my mashes at 1 hour plus no matter.

 

[kanzimonson]

Also worth considering is the completeness of conversion. A (theoretical) kettle of 100% maltotriose won't be fermentable to ale yeast, yet it will indicate full conversion with an iodine test.

It'd be interesting to do this experiment again but run off some wort every four minutes, ferment it, and see what the attenuation is. It'd be a lot of work so I doubt anyone's gonna try it.