 I always get a lot of questions about malting corn and it’s been on my “to-do” list for years. So many projects, so little time! Fortunately I recently received this great description from a fellow home maltster Jonathan Shockley who is having some success using popcorn. I can’t wait to try this.
“For starters, I have found that yellow popcorn works much better than white. Not sure why, but the white doesn’t germinate as evenly. My process is as follows. Start with 4 pounds of yellow popcorn. The starting moisture content was around 13.5%. This seems to be a general characteristic of popcorn, because apparently it won’t pop unless the moisture content is above 13.5% and of course any higher and you would risk spoilage. Steeped in de-chlorinated water for 8 hours, with 8 hours rest in between. It took only 3 steeps to reach about 45% moisture. On previous batches I found that even after 5 steeps the corn would only take up so much. Don’t really understand why that is. The steeping was done at 73F for both steep and air rest. I also let the air rest take place in a colander so there would be airflow under and over, and any residual moisture would trickle out. Not sure if this was necessary, but I spray StarSan on everything during the steeping, and germination process, even the spoon I stir with. The germination took about 5 days. It’s hard to check corn the way you do other grains, as the rub test doesn’t really work. I find I have to cut the kernel with a knife, and dig out the starch. Anyway, I have decided to stop germination when the acrospires is just longer than the grain. This is slightly more modified than barley, but the total diastatic power of popcorn under the best of circumstances is only about 40 Lintner (based on what I’ve read online). I have never had problems with mold during germination. I dry out the popcorn for 2 days over a fan with about 90 degrees F (it’s summer in Virginia and very hot in my attic). After that, I took the popcorn and kilned it at about 140F for 8 hours. My goal was to preserve as much DP as possible. I’m pretty sure every batch of popcorn malt I’ve made has been ok. Where I mess up is on the mash, which I think I finally have figured out. As you mentioned to me in a previous email, you have to use a decantation. I use a 1 to 1 water to grain ratio. I start by milling the popcorn almost to flour. You have to use a fine mesh brew bag for this to work. I start the mash at 140F for 30 minutes. This gets the enzymes activated. I then decant off about ¾ of the liquid and set it aside. I add the same amount of water as liquid removed and bring it to a boil. FYI, it’s a little messy. After the corn has gelatinized, I let it cool some then add back the removed wort. I make sure the temperature is around 150 and then just let it sit for about 2 hours. After all that, I check the gravity and do an iodine test. My last attempt yielded a wort around 1030 and iodine test was negative. This next part may not be necessary, but after the mash, the wort looked horrible. I have a large refrigerator (and it was late) so I put the kettle in the refrigerator and left it overnight. The next morning all the sediment in the wort had settled and I had about 2 gallons of clear wort. The color of the wort was much darker than I had expected. I then decanted off just the clear liquid and proceeded with the boil.” Thank-you Jonathan! I’ve also come across this historical text regarding corn in the American Practical Brewer and Tanner by Joseph Coppinger 1815: Indian Corn Malt, a Valuable Auxiliary to Brewing Materials. A very interesting read: This species of grain well managed, and made into malt, will be found alike useful to the brewer and distiller, but it is peculiarly adapted to the brewing of porter; further, it is known to possess more saccharine matter than any other grain used in either brewing or distilling, joined to the advantage of not interfering with the season for malting barley, as this should commence when the former ceases. The summer months are the fittest for malting this kind of grain, and can be only very defectively made at any other season, as it requires a high temperature to force germination, and cause it to give out all its sweet. The following process, it is expected, will be found to answer every purpose wished for: suppose your steep to contain sixty bushels, after you have levelled it off, let on your water as directed in malting barley; you should give fresh water to your steep at the end of twenty-four hours. If it is southern corn you are malting, it will require to remain in steep seventy-two hours in the whole; if it be northern corn, it will require ninety-six hours, there being a considerable difference in the density of these two kinds of grain; the hardest, of course, requires the most water; and, in all cases, the fresher Indian corn is from the cob the better it will malt. When you have accomplished the necessary time in your steep, you let off your water; and, when sufficiently drained, let it down in your couch frame, where it will require turning once in twelve hours, in order to keep it of equal temperature; the depth of the grain should be about two feet and a half in the frame; as it begins to germinate and grow, open your frame, and thin it down at every turning, until you reduce its thickness to six or seven inches; thus extending it on your lower floor, turning it more frequently, as the growth is rapid. The vegetation of the grain, together with the turning, will by this time make the watering pot necessary; the criterion by which you will judge of its fitness for the water, is as soon as you perceive the root or acrospire begins to wither. Two thirds of your water is to be distributed over the surface of your couch for the first watering, which will require thirty-two gallons, and when turned back again, sixteen gallons for the second watering, making in the whole forty-eight gallons of water to sixty bushels of corn. This water should be put on with a gardener’s watering pot, as equally as possible. Supposing this pot to contain four gallons, it will make eight pots for the first watering, and four for the second. In this stage of the operation the turnings on the floor should be very frequent, in order to keep the grain cool, as the heat of the weather, at this season, will be sufficient to promote and perfect the vegetation. The second day after the first watering, if the blade is not sufficiently grown, water again, but in less quantity, say one half. It will be now four or five days more before the couch is ready for the kiln, which will be ascertained by the blade becoming the full length of the corn. After this it should be thrown on the upper floor, and suffered to wither for a couple of days, turning it frequently; by this time the blade will have a yellow appearance, the grain will become tender, and, if tasted, be found uncommonly sweet; in this state it may be committed to the kiln, and dried in the usual way. N. B. It will generally take ten days after it is out of the steep to perfect the malting of southern corn, and twelve days for northern. (this includes kilning)
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Brewing Beer The Hard Way 