Acorns to wort

Preparing the acorns for mashing

I don't know that soaking to remove tannin is necessary for these acorns, but I did it this first time just in case. I covered the dried acorns with cold (filtered) water and let them sit for a couple of hours. They soaked up some of the water, and the remainder turned a little cloudy and green. Surprising, given that the acorns are a chocolate brown.

After a couple of hours I drained the acorns and covered them again with fresh water, this time about twice as much as needed to cover. I was thinking if they just soak it all up, the tannin may be in the water but the water is inside the acorns, not out as desired. I let this go another couple of hours. I repeated this several times. One soaking was overnight, so longer than two hours, and another was a few hours while we were at church. They were soaking for more than 24 hours, all together.

In the last installment I mentioned a skin on the outside of the acorns that doesn't always come off easily. Some of it comes off during the drying, so you get flakes floating around, and the rest
seems to come off during the soaking. I haven't thought of an easy way to separate acorns from flakes. The acorns settle more quickly than the flakes in water if they're all stirred vigorously, but the flakes still settle fairly fast, so without a deep container it's not terribly effective. I removed quite a lot of the flakes by hand, while transferring from the sieve back into the jar in which I was soaking them.

During soaking, my acorns turned an unappetizing greenish-gray. When Lynn baked and soaked some for roasting, to see if they made good snack food, they came out "blonde" after soaking, and dark brown again after roasting. Hopefully the beer won't come out greenish-gray.

Some of the acorns after soaking. This was intended to show the odd greenish-gray color, but I was aware that camera-monitor systems don't reproduce color very well.

 I then ran them through the fine blade of a meat grinder. They are tender enough for this after the soaking.

Meat grinder, ground acorns, and acorns. Note the circa 1980 appliance color. The box says "Harvest Gold," but it leans toward avocado. No doubt it has changed in those 35 years.

Recipe and mash

I did an adjunct mash with the acorns, the day before the main mash. Following Mosher's description in Radical Brewing, I mashed the ground acorns and about half as much six-row malt together. I used rests at about 100, 120, and 155 degrees. Mosher's description doesn't include the rest at 100 degrees, but I was hoping this rest, which is supposed to help degrade glucans or gums, would help break down the acorns. After boiling it I let it cool overnight. In the morning I heated it to about boiling and mixed it into the main mash just after doughing in.

Adjunct mash, after sitting overnight. Thankfully the color is no longer greenish-gray.

For the recipe, I was torn between making a beer that might come out too boring, and one in which other flavors are confused with acorn flavors. An acorn IPA with Brett is out for this first try, at least. A recipe of acorns, pilsner malt, and a small amount of hops leans a little too close to acorn tea. So, I'm aiming at a brown ale (nut-brown, in this case) that's not too roasty but would probably be okay without the acorns. The recipe is

Adjunct mash

1 lb six-row malt
2 lbs acorns (shelled and dried, before soaking)

Main mash

8 lbs pale ale malt
1/2 lb 60L crystal malt
1/2 lb victory malt
1/4 lb chocolate malt

Hops

3/4 oz Horizon pellets, 10.1% AA, 60 mins
1/2 oz Willamette pellets, 5.2 % AA, 20 mins

Yeast

Wyeast American Ale 2 (1272).

I intended this to give an OG of 1.058, and 35 IBUs.

The home brewery (in the garage). It's mostly pretty simple. This really has nothing to do with acorn beer, I'm just throwing it in.

I used a no-sparge procedure. I was aiming at 6.5 gallons of runoff, but got 7.5. Apparently the acorns don't hold a lot of water, but that doesn't explain it all. Probably I added more water to the mash than intended. The runoff had a gravity of about 1.041, which, with the volume, is less extract than I hoped to get. I'm guessing it's because the acorns don't break down much in the mash. The adjunct mash still had lots of fairly hard bits in it.

I boiled the wort for 90 minutes. At the end of the boil and cooling, the actual OG was 1.053, and the volume was a little less than 6 gallons, 5.5 in the fermenter. The wort is a dark brown, dark enough to be a brown porter, I'm pretty sure. Some of that seems to be from the acorns, since the malt bill by itself shouldn't give wort that dark. There is evident acorn flavor in it, not intense but not too subtle, either. It may stand out more after fermentation.

Fermentation didn't start for more than 24 hours. I oxygenated well, so either I should have kept it warmer, or I should have made a starter, or both. (Oxygenation worries me, in a case like this. I'd think there's more time for the oxygen to do bad things before the yeast eats it.) The rest of the fermentation, secondary fermentation, and kegging will be completely standard, so I won't write about that, unless something weird happens.

Acorn beer beginnings

There are a lot of oak trees in this part of New Jersey, including some on our property. They drop acorns every Fall, but some years they drop a lot. Doesn't "acorn beer" sound appealing for Fall, like "nut brown ale?" I've semi-joked about it almost since I started homebrewing, in 1997. So this year (2015) the oak trees are dropping a lot of acorns. Remembering my comments, Lynn went and collected a little more than four pounds of acorns from the front yard, intending that I try them. How could I refuse? I love trying things, if there isn't too much work, sometimes even if there is.

I've googled "acorn beer," and found a bunch of hits on homebrew sites from people asking whether anyone had tried acorn beer. There was some discussion, but few mentions of results. The one I remember was from someone who tried making about a gallon of beer. He mentioned that it was quite bitter, and he'd try aging it to see if it smoothed out. I got the impression he did not soak the acorns to remove the tannin. So maybe there will be something worthwhile in this blog.

Acorns

I've also googled acorns, trying to find information on processing them. Korean cuisine seems to include the use of acorn flour, and you can get it on-line. I'm concerned about it being thoroughly processed, acorn starch, you might say, but I may be wrong. In any case, it's more aesthetically appealing to use acorns from my own yard.

I've found conflicting information on the nutritional content of acorns. Some say it's very close to that of barley, so good for beer. Others say it has a lot of fat, and so can go rancid. I suspect the different kinds of oaks produce acorns with different nutritional content.

Lynn tells me that the oak in the front yard is an Eastern White Oak. White oaks are supposed to have acorns with less tannin in them. And in fact, these acorns are pretty mild. We tried some raw, and they really don't make you pucker all that much, roughly the same as a walnut. By contrast, there is an oak in the back yard that Lynn says is a pin oak, a kind of red oak. Its acorns are very bitter. Good thing the white oak acorns are the less bitter ones, since they're quite a bit larger.

So lesson 1, white oak acorns may be better than others because of lower tannins.

By the way, they taste unusual but pleasant, kind of buttery, with a little sweetness in the aftertaste. Lynn collected some more, and shelled and soaked to remove tannins. She then oiled, roasted, and salted them to see if they worked as nuts for snacks. They don't quite. The taste is interesting, but they're a little hard, and the texture is a little odd.

Initial processing

Following some on-line sources, we baked them on low heat to kill any eggs or grubs in them. The source I followed said to bake them at 200°F for 30 minutes, so I did that, with the acorns spread one layer deep on three cookie sheets. I just turned the oven off after a half hour and let them cool overnight. The next morning Lynn took them out and put them on the kitchen counter. After a while she found a grub crawling away, so clearly they hadn't gotten hot enough. Lynn then baked them at 250°F for an hour. Although the meats were a fairly light tan when raw, after the time in the oven they are dark brown. They look like chocolate.

Then came the shelling. I used an ordinary nutcracker, the two-armed class-2 lever kind of thing, not the kind with the wooden figure that cracks the nut in its jaw. After an entire Eagles game I had worked through only half of the four plus pounds.

After another Eagles game plus fifteen minutes I had shelled them all.

There is a skin that sticks to some of the acorn meats, that's hard to get off, so I did not worry too much about it. It will mostly come off during soaking or mashing.

I stored the acorns in the big jar in the picture, flushed with CO₂, maybe being more cautious than necessary. After a few days I noticed that a few acorns had a little fuzz on them, I assume mold. Apparently they hadn't dried enough yet. So I baked them again for an hour or so (don't remember) at 200°F. I put them back in the big jar, which I had cleaned, sanitized, dried, and put in my chest freezer (~45°F). As soon as the acorns entered the jar, water started condensing inside it, so they were still out-gassing water. The next day I put them in the upper oven with the oven light on and the door cracked, as Lynn suggested, and left them for a day. No more condensation in the jar. I can't get to the beer for a month or so, so I flushed the jar with CO₂ again, and I'm storing them in the chest freezer. There are a little more than two pounds of acorns, now that they're shelled and dried.

Introduction

I thought it would be better to document my experiment with acorn beer in a blog than to post occasionally to social media. No doubt there will be other topics at some point. I have a blog about our experience with hurricane Irene, but I thought I'd leave that alone, rather than add acorn beer posts to it.