Merry Christmas, all. While my mash ferments, I have been scouring the forum and the internet to learn more about mashing with enzymes and mash chemistry and enzymatic action in general. Pretty neat stuff.
Recall that I was confused and worried when I measured gravity (via refractometer) about 1.5 hours into the gelatinization/gelation stage at 1.06, and it never increased from that point even with the second addition of enzymes and further resting. I thought that the gravity should rise throughout the process as the mash converted. When it didn't, I thought perhaps something had gone wrong in the conversion process. However, it turns out that starch, once dissolved into solution, gives very similar gravity readings as the mash does after conversion. See:
http://braukaiser.com/blog/blog/2011/03 ... t-content/
Greatly simplified, It's like measuring the weight of a bowl full of spaghetti noodles, and then chopping them up into small pieces and weighing again. The noodles weigh the same before and after chopping. The gelatinization process, which SEBStar speeds up, is like cutting open bags of noodles and dumping them in the bowl, chopping them into random sized bits on the way. Unopened bags of noodles are like starch tied up in a piece of grain before it is dissolved in the mash liquid. After opening the bags (gelatinizing) the longest bits are analogous to starches freed from the grain, but still needing to be broken down into simple sugars. Medium sized bits are the dextrines and complex sugars, with the shortest bits being the simple sugars we are after. Once the random sized noodle pieces are in the bowl (dissolved in the mash water), the second enzyme, SEBAmyl goes to work chopping all these bits into even smaller pieces that are largely glucose, a highly fermentable sugar.
So, that explains why I saw all the gravity I would ever get appear after gelatinization. An iodine test for conversion (which I didn't do, Doh!) would likely have shown a positive reaction for starch at the first gravity reading and turned negative after the second addition of gluco-amylase and a sufficient rest.
This mash taught me some useful things: I can take a gravity reading any time after gelatinization to see how much extraction occurred so I know the potential of my mash. Also, since the gravity reading never changed after the initial measurement, 90 minutes was plenty of time to dissolve all the starch that was ever going to be. I can now experiment with measuring gravity frequently during gelatinization to find the minimum time needed for reaching the maximum extract. If the visual thinning of the mash correlates to dissolving the starches, this might be almost instantaneous. Probably not since the manufacturers directions and pintoshines process calls for a rest at cereal mash temps. Perhaps the gelatinization is very quick but the first round of chopping up the starch molecules into random lengths takes a while.
So, now the only question is how well did the SEBAmyl work to convert the longer chain molucules into simple sugars, thus increasing the fermentability of the mash. Well, I got the answer today. I pitched this midday Saturday and checked it at midday today (Wednesday), so it is right at 4 days. It is not done fermenting. The blow-off tubes are still bubbling at the rate of about 1 or 2 bubbles a second, the cap hasn't fallen, and the wash hasn't cleared. Even so, I took a gravity reading. It was .997
![Shocked :esurprised:](./images/smilies/icon_e_surprised.gif)
Looks like this stuff is fermentable, alright. The enzymes worked fine!
Very nice results so far. Thanks Woodshed
![Clapping :clap:](./images/smilies/icon_clap.gif)