decoction effects?

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Enpitsu

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i made a partial mash batch yesterday using this technique:

http://byo.com/stories/article/indices/48-partial-mashing/511-countertop-partial-mashing

Added 140-145 F water to 4lbs grain / 4qts water mash, and it got to 135F, right as expected!

At 30 minutes, took out about 1/3, boiled, added back to mash - ended at ~160F, which after 5 minutes uncovered with some stirring got to 155F, so i covered and let sit for 40 more minutes.

problem is, my efficiency was super low, and i ended up with a SG potential of only 4-5%!!!! Considering i was aiming for 6-8% ( i added sugar and extra DME than callled for to the wort), i'm confused. does boiling the mash affect the sugars that are able to be used? in other words, did my boiling 1/3 of the mash before it sat at 155F reduce my potential sugars by 1/3?
 
I usually mash the decoction before boiling it (let it sit at ~160 F for 20 min, then boil). With such a small volume, you would have to be very carefull to pull a thick mash or you can boil a third of your amylases and get slow conversion.

That said, sparge and grain crush are probably more important for efficiency. I don't know exactly what you did to sparge your grains, but usually the more first wort you extract the better efficiency you will end up with. Especially since you are using a stiff mash, I would suggest letting that grain bag drip as long as you can stand before you add the sparge water. As for grain crush, not too much you can do about that unless you get a grain mill.
 
thanks all.

the primary has gone mad - more mad than i've ever seen it with fermentation. so i'm thinking maybe my hydrometer got stuck. also, i tried tap water in it and it gave me a reading of <1.000. sooooooooooooo, maybe my hydro is just bad.

great link about the decoction.
 
great link about the decoction.

If you watch Kai's youtube videos you will see that he rests (protein rest optional) the decoction portion with its own mash at 155 for 15 minutes before boiling. This attempts to finish conversion on the volume being decocted and I noticed you did not mention any such mash.
 
randar - this was exactly what i was wondering about! next time, if i do choose another decoction profile, i will let it rest at around that temperature for some time. no, i did not do that this time.

i'm going to keep this one going and see how it turns out and i'll let you know.
 
randar - this was exactly what i was wondering about! next time, if i do choose another decoction profile, i will let it rest at around that temperature for some time. no, i did not do that this time.

i'm going to keep this one going and see how it turns out and i'll let you know.
You only need to let it rest at 160*-ish for ~10 minutes, maybe even less. It should be mostly converted by then and will continue to convert for a bit as you heat it from there. You don't need to fully convert the decoction, you'll convert it all later in the main mash anyway.
 
You only need to let it rest at 160*-ish for ~10 minutes, maybe even less. It should be mostly converted by then and will continue to convert for a bit as you heat it from there. You don't need to fully convert the decoction, you'll convert it all later in the main mash anyway.

Maybe I am arguing semantics here, but you will destroy any enzymatic activity int he decoction portion when you boil it so you will lose SOME conversion opportunity by boiling it. This is precisely why you let it rest to get what you can out of that volume (disclaimer: I have never done a decoction). :cross:
 
There should be a large surplus of active enzymes in the main mash. Since you are hydrating and solublizing starches that may not have been available without it, the decoction boil may increase efficiency (conversion opportunity).
 
There should be a large surplus of active enzymes in the main mash. Since you are hydrating and solublizing starches that may not have been available without it, the decoction boil may increase efficiency (conversion opportunity).

I've not seen anyone (limited reading on decoctions) advocate skipping the first rest of the decoction and Kai explicitly uses it and tests for conversion before stepping up to boil. It's not that I don't believe your reasoning, it is... reasonable :D... just yearning for more detailed information/study to back this up.
 
Most of the enzymes stay in the liquid/main mash. I thought Kaiser mentioned that you don't need complete conversion in either the video or the article, I know he's mentioned it in threads. I quickly scanned the article and all I could find was this:
After the decoction is converted or almost converted (iodine test) the heating of the mash is resumed.

And 944 touched on another point, that during the decoction boil you liberate starches that weren't available during the sacc rest so the decoction will have some non-converted starch anyway.

In any case you might be surprised if you do an iodine test on a decoction that has rested for only 5 minutes @ ~160* F. The alpha amylase works very fast at that temp.
 
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