Preboiling to remove alkalinity also removes oxygen.
Doughing in at the acid rest temperature slows oxidation reactions, and washes away the starch and amylase enzymes. Most of the LOX enzymes are found in the husk where it meets the arcospire. If the crush preserves the husk, LOX will not leech quickly into the wort. Pulling the first decoction and boiling it will denature LOX before it has a chance to inflict damage on the main mash.
Additionally, decoction boils create melanoidins which are powerful antioxidants and can fight oxygen as it diffuses into the main mash.
Just some food for thought.
Statistics: Posted by Techbrau — Mon Dec 07, 2015 1:27 pm
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On the other side I quite like the idea of a combination heating the water then using co2 for the finish. It seems faster to me.
There will be a reasonable middle-ground somewhere. Time is an issue for me.
My focus is currently on water composition, so I am anxious not disturbing it by any means.
When I decoct I always transfer very carefully, avoiding any o2 intake (that's how I learned it).
I am not sure one has to be 100% o2 free. Time and many happy drinks inbetween, will tell
Statistics: Posted by Weizenberg — Mon Dec 07, 2015 1:23 pm
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You could verify this by taking pH samples of your water before and after boiling.
Statistics: Posted by Roachbrau — Mon Dec 07, 2015 12:06 pm
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I find it interesting that it didn't occur to Fix at all that the initial oxygen concentration of brewing water at mashing temperatures is going to be approximately 6ppm.
I also found it very interesting that Narziss' research from the 1970s was so influential that it inspired breweries all across Europe to invest in low O2 equipment. And we now know that their brewing water is degassed to less than 0.1 ppm oxygen as well...
Statistics: Posted by Techbrau — Mon Dec 07, 2015 11:45 am
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Statistics: Posted by wobdee — Mon Dec 07, 2015 10:16 am
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His sparge tun has empty space that is filled with water before the grain goes in. This water is de-oxygenated with CO2.
I *might* try de-oxygenating the dough-in water just before it's used. I am not sure about boiling it due to the time and energy cost, as well as the potential uncertainty about the actual liquor composition. My attitude may change though
Statistics: Posted by Weizenberg — Sun Dec 06, 2015 6:05 pm
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The easiest way that I can think to do this right now is adding potassium metabisulfite to chemically buffer out any oxygen which diffuses into the mash. Using 1/3 of a tablet per gallon of water (approximately 208 mg of potassium metabisulfite) should add about 22 ppm of sulfites to the mash, which should be enough to take care of oxygen without adding to many extra minerals. It will change the water profile, but it's hard to know by how much since some of the sulfites escape as SO2 during the boil and others end up forming SO4 and staying in the wort. My best estimate would be to figure that using this method will give you an extra 10 ppm of SO4 than was originally in your water, along with a couple ppm of potassium. Boiling the wort should destroy or drive off everything added by the k-meta except the aforementioned potassium and SO4.
I still think pre-boiling is a good idea, because you know that the oxygen content is 0 immediately after boiling. Otherwise, you'd have to try and guess how much extra k-meta to add in order to scavenge all of the initial dissolved oxygen and still have enough sulfites left over in solution to capture any that diffuses in. Just remember to add your potassium metabisulfite after pre boiling.
Statistics: Posted by Techbrau — Sun Dec 06, 2015 8:58 am
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