Originally Posted by igliashon
My guess is that chestnut starch is harder to get into solution than most grain starch; but I can't imagine why, presuming you get a comparably-fine grind, that a 15-20 minute boil wouldn't fully gelatinize them, after which point you could cool them to optimal saccharification temp, add the enzymes, and get full conversion inside 2 hours. But I'm also not a food scientist, so there could be a piece I'm missing.
Update: Over the holidays I saw fresh chestnuts on sale, so chopped, dried in a food dehydrator, and then ground them in my corona mill. I tried exactly this: boiling for 15 minutes, then cooling to saccarification temp and adding enzymes.
The answer to this question is a resounding no, it can't (shouldn't) be done that way. The boiling of the chestnut chips left a lot of starch particles in the solution that wouldn't convert. I finished the brew session anyways, and had a good primary fermentation, but I can see a good 6-12 inches of starch that has settled in my carboy. My yield off of this 5 gallon batch will be lucky to be 2.5 gallons.
I'm going to do another experiment though, testing brix and starch conversion on a long mash to see if that long mash is truly necessary (especially when adding 5# of sugar). I suspect that I can get a lot of flavor/color out of a much shorter mash, by only sacrificing a few gravity points.
Also, for those out there that think they can chop, dry, and grind their own chestnut chips for a fraction of the price of Chestnut Trails .... this is a huge PITA, and I now think the Chestnut Trails chips are an incredible bargain, compared to the hours of work it took me to get only a few pounds.