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Old 09-16-2008, 06:38 PM   #21
Kaiser
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I'm assuming their clear beer has been partly due to filtering, but we'll see!
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Even if they filter, they should pay attention to haze forming proteins and to reduce the load on the filter. The less hazy the beer going into the filter is, the longer the filter can go before it needs to be replaced.

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So the maltster and Noonan (in the excerpt quoted above) recommend a lower temp rest...but Noonan's book says otherwise?? My copy of the book is on order and should be here soon!


I don’t think there is a contradiction between the maltster’s and Noonan’s suggestions. You are dealing with a very high protein malt, and Noonan’s recommendation of skipping the protein rest for SNR ratios of 40 and more is likely for low (9-10% protein) malts.

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Old 09-16-2008, 09:07 PM   #22
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I don’t think there is a contradiction between the maltster’s and Noonan’s suggestions. You are dealing with a very high protein malt, and Noonan’s recommendation of skipping the protein rest for SNR ratios of 40 and more is likely for low (9-10% protein) malts.

Kai
Not to beat this thread to death, but this is curious. Kai, could you elaborate more on protein-related rest temps and how they relate to SNR and Total Protein?... or point me to a source that explains it? I've studied the Noonan stuff, but there appears to be some gaps in his information. Thanks.

(PS: I listened to your guest appearance on BBR... very informative and you really sound like you've put a lot of time and research into the science behind brewing. It was a fun listen because you seem to have brewing knowledge for the sake of learning and brewing good beer, without the ego. Great job!)
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Old 09-17-2008, 01:57 AM   #23
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As I see it, the protein rests (starting at 45C and ending at 55C) serve to reduce the size of the protein molecules. The smallest are consumed by the yeast, the medium long ones contribute to body, head retention and haze and the longer ones coagulate during the boil and cooling. With regular protein malts that have a low soluble nitrogen ratio, a concern exists regarding the amount of the smallest proteins, the amino acids. For a proper fermentation enough FAN (free amino nitrogen) is needed and a protein rest serves to creates more. With high protein malts the protein destructive nature of the low temp rests can help in reducing the number of larger proteins (which can cause excessive haze) by breaking them down into smaller ones that get eaten by the yeast. But if overdone, to many may be broken down and the body/head retention will suffer as well.

But unfortunately there is not a small number of enzymes responsible for that (like the amylases for starch) and it doesn't seem to be as well studied either. Lower temps 45-50C are known to favor the creation of short proteins and higher temps 50-55C are known to favor the creation of longer protein chains. Similar to fermentable sugars ad unfermentable dextrines, but I don't know how valid this analogy is.

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Old 09-17-2008, 12:12 PM   #24
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Thanks, Kai. That's probably the most concise and informative explanation of protein rests I've seen.

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