First AG Mash

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CanadianWhisky
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First AG Mash

Post by CanadianWhisky »

Well, after much reading I finally got around to doing my first AG mash and one thing is for sure, it's easier said than done at least the first time. Not sure how bad I messed it up yet either but I'm starting to wonder. I went the BIAB route because I'm cheap, but after dealing with 15 pounds of wet grain I think I'll pony up the $100 and build a mash tun.

So I started with with 7.5 gallons of water at a strike temperature (after much mucking about) of 158 degrees. Added this to my bag of 15 pounds of ground 2 row barley in an old cooler and stirred. Temp came down to 154 degrees so I added a quart of cold water and the thermometer went down to 150 and I closed the lid. Checked a half hour later and the thermometer was reading 156! I guess the probe was in a cool spot and the temp went up as the heat equalized. Left the lid open and stirred for half an hour until the temp hit 151 and I closed the lid again. An hour after that it was 149 and i drained it into the fermentor and squeezed the bag. I then added a gallon and a half of 153 degree water to rinse the grain and get more sugar out. First runnings measured 1.061 and the second runnings were 1.030. Combined I got 1.052. Combined and cooled to 84 degrees and pitched my yeast starter of 2 tablespoons of bread yeast that i had rehydrated for about two hours. 8 hours later it was bubbling and smelled like it was off and running. 19 hours later the fermenter is 80 degrees and a sample measures at 1.014.

Questions.
Did most of my mashing time being at about 156 do me any harm besides creating more unfermentable sugars?
Even with there being no large pieces of anything, is there enough sediment in an all grain brew to throw off the hydrometer reading?
If the initial gravity was 1.052, is there any possible way it could have fermented down to 1.014 in 15 hours? I'm sceptical. Fermentation does sound vigorous, but I'm worried I messed up somewhere. Only sure way is to distill it when it's done, but I'm worried.
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still_stirrin
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Re: First AG Mash

Post by still_stirrin »

CanadianWhisky wrote:Questions.
Did most of my mashing time being at about 156 do me any harm besides creating more unfermentable sugars?
That's probably what happened.
Even with there being no large pieces of anything, is there enough sediment in an all grain brew to throw off the hydrometer reading?
Probably not. It more than likely is the non-fermentables you set with your mash.
If the initial gravity was 1.052, is there any possible way it could have fermented down to 1.014 in 15 hours? I'm sceptical. Fermentation does sound vigorous, but I'm worried I messed up somewhere.
Temperature correct your gravity reading. With elevated (ferment) temperatures, your hydrometer will read lower than it actually is.
Only sure way is to distill it when it's done, but I'm worried.
You're probably not done with only 15-20 hours of fermentation. 72 hours (3 days) would be a very aggressive ferment. 96 would be even more likely. Wait a little longer.

And one more pointer: you don't need to rehydrate your yeast for 2 hours. It's actually better to rehydrate for 15-20 minutes only and then pitch it into the fermenter. Obviously, yours worked...as I would expect. But the yeast will be viable with a much shorter hydration period.

All you really need to do is to moisten the cell walls and fill the cells with water so they don't implode when poured into the higher density wort/must.
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CanadianWhisky
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Re: First AG Mash

Post by CanadianWhisky »

Thanks for the reply. All readings are already temp corrected. As for being done, I know I'm not. Will be another 4 days before I have time to run it in any case. I've just never had sg drop that much that fast so I thought something else must be at play. The yeast only rehydrated for 2 hours because it took longer than expected to cool to pitching temp. Oops.
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Jimy Dee
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Re: First AG Mash

Post by Jimy Dee »

I am about to do my first AG mash. Is it critical to get the heat at 150 ? On reading this post am I correct in understanding that the 6 degrees higher than this 150 did damage and reduced the amount of fermentable sugars?
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still_stirrin
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Re: First AG Mash

Post by still_stirrin »

Jimy Dee wrote:I am about to do my first AG mash. Is it critical to get the heat at 150 ? On reading this post am I correct in understanding that the 6 degrees higher than this 150 did damage and reduced the amount of fermentable sugars?
In a brewer’s mash we are concerned with the activity of two main enzymes, alpha and beta amylase.

Alpha amylase is the enzyme responsible for breaking large, complex, insoluble starch molecules into smaller, soluble molecules. It is stable in hot, watery mashes and will convert starch to soluble sugars in a temperature range from 145° to 158° F. It requires calcium as a co-factor.

Beta amylase is the other mash enzyme capable of degrading starch. Through its action, it is the enzyme largely responsible for creating large amounts of fermentable sugar. It breaks starch down systematically to produce maltose. Beta amylase is active between 131° and 149° F. But like all enzymes, its activity reaches a peak, declines, and then drops precipitously as temperature increases. The rate is also dependent on the amount of enzyme present. It takes time for all of the enzyme to be destroyed, but what is still intact works very quickly. So as the mash temperature approaches 149° F, beta amylase is operating at its fastest rate but it is also being denatured.

This may seem trivial, but at these higher temperatures the denaturation is so rapid that the enzyme is mostly gone in less than 5 minutes. Also, in a homebrewer’s mash tun, where the grain may be poured into very hot water, the exposure to very high heat for the few seconds before the mixture becomes homogenous may work to destroy the fragile enzymes. This means that, in a practical sense, the manipulation of beta amylase activity can be utilized to control the fermentability of the wort. If the mash is allowed to “stand” at a temperature that favors the action of beta amylase, then a greater proportion of the sugars extracted from the malt will be maltose and hence the wort will prove more fermentable.

In commercial brewers' experience, it was found that changing the mash temperature from 149° to 156° F raised the beer’s terminal gravity from 1.008 to 1.014. This is a significant difference.
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Jimy Dee
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Re: First AG Mash

Post by Jimy Dee »

Brilliant reply - thanks a mil.

As a follow on to this please - I was thinking of adding 30% MALTED barley to 70% cracked UNmalted barley.

Question - Am I correct in saying that it is OK to bring the cracked UNmalted grains to a boil for 10 mins and let them sit for an hour of so to allow the grains to swell and get ready for conversion. (Obviously the malted barley is not added until the temp is 65 degrees Celsius)
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Re: First AG Mash

Post by still_stirrin »

Crushed raw (unmalted) barley does not need to be boiled. Corn is boiled to gelatinize the starch so it can be mashed. Raw barley will mash without gelatinization because its starches are already available to the enzymes once the husk has been crushed.

Ironically, the same would apply to raw rye grain as well. Crush it and mash with malt...no gelatinization required. Grains with hard seeds like wheat and rice (and corn) benefit from gelatinization, especially if flaked. They mash much easier following the flaking process.

Keeping the 30% malted barley in your grainbill will help ensure success with the mash conversion too. Crush the grains and mash at the beta amylase enzyme temperatures (60-65*C) and you should be fine.
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Jimy Dee
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Re: First AG Mash

Post by Jimy Dee »

SS - many many thanks, I am waiting for my bag of malted barley to arrive and as soon as it does I am going to attack my first AG mash. Cannot wait. Willing help from the likes of you and others makes this a winner of a web site. Thanks SS. Jim
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