Decoction mash and Astringent

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Decoction mash and Astringent

Postby Raydownunder » Thu May 08, 2003 4:19 am

Decoction mash and Astringent

Hi all

The title tells the story. I have a problem with my decoction mash. I can’t put my finger on it but it is in my last 3 batches. They all have a small astringent taste after 4 weeks in the bottle and after that it gets worse. I really don’t know what I am doing wrong.

This is my decoction procedure for a 22L batch and an average of 6kg grains.

1. Crush grains and add to 15 L of 58C water.
2. Mash at 54C for 15 min
3. Remove 40% of the mash for the first decoction
4. Raise decoction temperature to72C hold for 20 minutes
5. Raise decoction to a boil and boil for 20 minutes
6. Add the decoction back to the mash to achieve a temperature of 64C.hold for 20min
7. Remove 40% of the mash for the second decoction.
8. Bring to boil, and let boil 20 min
9. Return decoction to mash, yielding a temperature of 73C hold for 20 minutes
10. Sparge with 77C water

I keep the above temperatures exactly with my digital temp gauge.

The last batch I used 1 tablespoon of Sodium metabisulphite in the mash as I heard this will work, but I have to wait till tasting day in 4 weeks.

Most of these beers are lagers and I am lagering them for 4 weeks at 2C.

My first few batches were fine and one has just one a silver metal. I am thinking of going back to single infusion mashes where this astringent taste was never there. All the malts used are German so why would I have the astringent taste with these malts, which a lot of brewers use decoction mashing in Germany.

Does anyone have these problems?

Ray Mills
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Boil with the grain?

Postby fitz » Thu May 08, 2003 5:11 am

Are you boiling the grain with the wort. That what it sounds like from your post. Any boiling, especially long boiling with grain in the wort will leave astringent properties in the final beer. If I am wrong, I sure someone will tell us, but that is what it sounds like to me. Boil the wort but not the grain. good luck.
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Boiling too long

Postby jayhawk » Thu May 08, 2003 10:34 am

I occasionnally decoct my mash to raise the temp if I miss the infusion temp. I have always felt that decocting is only for raising the temp of the mash, and that the decocting system was developed as a way to standardize beer production prior to thermometers being invented. I would think that the prolonged boiling of your decoctions would cause a release of tannins from the grain that is contained in the decoction. When I need to decoct, I bring the decoction portion of the mash to a boil and then immediately add it back to the main mash. I have never had any astringency problems, but I have noticed increased mash effeciency. Perhaps you should not boil the decoction so long next time.

Good luck
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Thanks Guys plus report

Postby Raydownunder » Sun May 11, 2003 4:02 pm

Hi all

Thanks for all the information on my decoction and astringent problems.

1. As suggested I will eliminate the protein rest altogether and mash at 64C for 1 hour. Remove about 30% for first decoction and bring to the boil only. Add this back and mash out at around 70C for 20 minutes.

2. I tasted my last 5 batches on the weekend, all made with the problem decoction mash. These are some findings.

a) The protein rest at 58C made all the beers to thin. A fine example was the Mailbock which had an OG of 1.070 and ended up tasting like a very nice Pilsner, the nice malty character expected was not there.

3. Three of the batches had astringent problems at different levels by this I mean two I could drink and perceiver with the problem and one I had to throw out. Of these beers they all had around 50% Munich malt and small amounts of Caramunich. The two beers (Mailbock and Pilsener) had no astringent problem only they were thin.

Will be making all those beers again but this time I think I have it right.
All in all an expensive exercise but gee its only a hobby.

Thanks again and
Ray Mills
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"infusion mash"

Postby beerbelly » Sun May 11, 2003 7:04 pm

grains have came along way,infusion mashing will save you trouble, 150 per hr dry, 158 malty, anymore questions, go to your local micro brew, they almost all infuse. when i mash out i ussualy dont let me strike water get over 180, tannins after that, plus the several times it takes you to get to 168 or so your wort is starting to clear
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Thin & Thick Fractions....

Postby Mesa Maltworks » Wed May 14, 2003 3:44 pm

If done properly by starting with a "thin" decoction (appx. 30% grain) and raising the temperature slowly while CONSTANTLY stirring until it reaches a boil, due to biochemical reactions (complex, difficult and too long to explain here) tannic extraction does not occur.

The second decoction typically takes place at around 70% mash and by then has raised to a high enough of a temperature by the reintroduction of the boiled "thin" first decoction that this tannic protection continues.

The keys are: constant stirring until a boil is obtained and rasing the mash slowly to the boil. Decoction can be pulled off successfully, but it requires strict attention and lots of temperature measurements to determine if you are raising the mash temperature at the right rate.
If you are doing a double decoction correctly to produce a 5 gallon final yield, this process should take around 4 hours from milling to kettle full !!!

Back in 1989, I did a bunch of experiments with American and British fully modified malts in both infusion and decoction mash regemins as well as "fully modified" European malts (which are typically less modified than their British and American counterparts)and compared the results among 10 BJCP judges. All grists, hops and yeast used were the same with the exception being the base malts.

The concensus was that the technique was wasted on the British and American malts, but was noticable when used with the Euro. malts. We also mashed with undermodified malts: Budvar and Gamb. Czech Pilsen. Of course, these malts require decoction. The overall flavor favorites came from the Euro. and undermodified mashes.

Now the decision to decoct or not comes down to a law of diminishing returns.... were the favorites 50% better? NO ! More like 5-10% better. But the input labor and hassle was over 150% more! It is also messy and requires more equipment. Fun to play with, but not something I would do all the time !

If anyone wants to read further about this, I can post more explicit decoction instructions including triple decoction (UGGH !).

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there are other reasons to decoct...

Postby vtterror » Thu May 15, 2003 4:52 am

Once in a while I like to do what a friend of mine calls a mini decoction (it's a technique she taught me). All it entails is after mashing the grains for about 35-40 min. @ 150 F, simply removing 1/3 of the thickest part of the mash, slowly bringing it up to a boil, and boiling for about 15 min. The decocted portion is added back to the rest of the mash, and sparging commences immediately.This process helps darken the color considerably due to caramelization of the sugars,and increases dextrins, which when all is said and done, actually improve the body in the final beer. Oh yes, and it does seem to improve mash efficiency slightly.Most malts these days are so well modified that a decoction mash isn't REALLY necessary...but it's still kinda cool to do once in a while.
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