I was at the grocery store when I noticed onions were on sale, 3 lb/$1. Naturally I thought "onions have a lot of sugar in them, I wonder if anyone has used them to make booze?" and bought $14 of onions. After doing some research I found that a couple of people had attempted to make onion spirits with added sugars to boost the ABV, but neither had been palatable. I decided that added sugars are for the weak and moved full steam ahead with a 100% onion batch.

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Step 0: Buy onions

https://imgur.com/a/3vAYDR8

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Step 1: Blend the onions.

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Blending 42 onions took longer than I expected. My blender overheated half way through, and my attempts to push onions through my meat grinder were relatively unsuccessful. Eventually I settled on quartering the onion and throwing the whole thing, skin and all, into the blender. The first couple of pounds of onions made me their bitch and I was forced to don goggles for the rest.

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Step 2: Cook the onions

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https://imgur.com/a/RAcoxGn

I boiled the onions to sterilize them (don't want any off flavors from wild yeast in my onion liquor...) and to hopefully soften the chunks enough that the yeast could pull out more sugar. It was at this point that my partner in crime came over and noted that you could smell onions from the street. I did not have any windows open.

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Step 3: Pitch yeast and wait

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I added the mash to two HDPE carboys, pitched the yeast, and waited a couple months. I wasn't sure how long it would take before the yeast converted all of the sugars they could obtain from the onion chunks.

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Step 4: Stripping run #1

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I added my ~8 gallon mash to the still and collected until I was too close to 100°C for my thermometer to know the difference, for a grand total of....

1500 mL @ 27%
1500 mL @ 6%
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Step 5: Evaluate yield and research how much sugar is actually in onions

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It isn't very much.

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Step 6: Construct smaller still, because you can't do anything with 3 liters in your current rig.

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Step 7: Redistill

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I distilled the 27% jar with 750 mL of the 6%, collected 1 liter, added the remaining 6%, and collected 1 liter. I did a slow spirit run with the final liter.

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The total yield after I cut out the heads and tails and added water was just over 700 mL of 47% pure onion liquor. Looking at the numbers I probably cut too wide, but it was pretty hard to identify the heady characteristics when you're getting punched in the face with onion.

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https://imgur.com/a/fKmPFV7

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Tasting notes:

The aroma is that of lightly caramelized yellow onions with a hint of Costco hot dog onion chunks. The first drop on your tongue is reminiscent of cheap scotch, followed by cocktail onion. The finish is pungent and mildly sweet, like raw onions from a cucumber salad mixed with Burger King onion rings.

All-in-all, it could be a lot worse. I'd give it a solid 3/10.

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Lessons learned:

Onions don't have as much sugar as I thought
Onions are a lot smellier than I thought
If I ever try to boil 42 lbs of onions in the house again my fiance will probably leave me
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Recipe:

42 lbs yellow onions
Water to 8 gallons
11 tsp yeast nutrient
2 packets yeast (I didn't record which type- either EC-1118 or D47)

Interesting comments:

Onions are packed with sulfoxides. If you grow onions in sulfate free soil/medium, than you don't really get that onion taste/odour from them, same with others alliums like chalots, and garlic.

That said, Onions are like 90% water, and 8% carbohydrates of which only like 50% of those carbohydrates are sugars that can be used by yeasts. The other 50% would be starches that make up the structure of the plant, some of which would be pectin based, so pectic enzymes might help eek out some more sugars, but only about 12% of that 8%.

But overall, I don't think adding enzymes would be worth it unless you wanted to do a comparison of enzyme-less vs enzymes.

If anyone else is going to try something like this, you can go over to https://www.traditionaloven.com/ and click Food Details at the top right. Then select from the right-side menu the category of foodstuff, and it has all the nutritional info for that thing.

Like Raw Onions.

I also forgot to mention that you can head over to Youtube, and watch this video by George from Barley and Hops Brewing, on how to determine the amount of convertable starches in foodstuffs. He uses potatoes in his example.

I love this post. Maybe you could try cooking with your punch in the face onion juice- flambé finish perhaps?

Reminds me somewhat of my experiment picking and mashing and fermenting and distilling 100L of wild growing quince (from a blackberry infested valley- really fun to pick in). I’d read wonderful stuff about quince liquor. I too nearly destroyed my very expensive powerful blender, spent hours destroying my kitchen, and after the labour of squeezing out the fermented juice, I discovered that ripe quinces apparently have very little in the way of fermentable sugars. After generous heads cuts to account for possible methanol from all the pectin I was left with just a very small amount of drinkable spirit, which though sort of nice and with a mildly pleasant mild flavour not entirely unlike quince, was rapidly consumed and forgotten while the memories and pains of the whole disastrous production lingered. I won’t be doing that again.