Onion Syrup?

Joined Jan 6, 2018
In an effort to create some French Laundry-esque powders, I ran some veggies through a masticating juicer and dried the pulp in the microwave according to the instructions in Thomas Keller's cookbook. The carrot and beet powders turned out great, and, feeling like I was on a roll, I went for onions next. Creating my own onion powder from fresh onions seemed like a good idea, so I ran three yellow onions through the juicer, collected the pulp, and was about to throw the juice away when I thought it would be fun to reduce it to an onion syrup. I have been reading Grant Achatz's book "Life, on the Line" and am all hopped up on the idea of unusual food textures. What I have in my brain looks like maple syrup and tastes like caramelized onions.

What actually resulted from reducing the juices of three onions (maybe 16 oz.) to a syrup (maybe 2 oz.) looked about right, smelled OK, and tasted absolutely terrible: Strong, sulfur-y, bitter, and generally unpleasant.

Is what I am trying to do possible? Clearly, this technique didn't work out. What I don't understand is what makes this reduced juice different (and so much worse) than caramelized onions? Anyone have any thoughts, educated guesses, or musings on the physical and chemical changes that did or did not happen?

Thanks in advance.

Joined Jan 6, 2018
I've done a fail attemp aswell some months ago. Tho I used powder I dehydrated myself. Mine was mild flavored but unpleasant. Can't wait to see the update on the post.
Joined Nov 5, 2007
Sounds like you basically concentrated the sulfuric components of the raw onions. Perhaps doing a low and slow braise in salted butter of the raw onions, not carmelizing them might be a better first step.

Joined Jan 6, 2018
It sure tastes like all the sulfuric compounds concentrated in the reduction. I guess I thought it would have cooked off in the process as I don't find whole caramelized onions to be bitter. Another potential culprit was that one of the three onions I cut up to juice burned my eyes something awful, which doesn't happen very often. Should I be throwing out onions if they emit especially strong fumes?

I saved the onion pulp, dried it, and crushed it into a powder as Keller suggests. It's not as pretty as the beet or carrot powders, but it definitely tastes better than the onion powder I have in my spice drawer.

Now I wonder what would happen if I caramelized the squeezed pulp like one would regular onions, possibly adding stock, wine, or some other flavorful liquid to cook down in place of the onion juice? If the juicing process helps to strip sulfurous compounds away, the resulting pulp might be a little tastier than caramelizing whole onions, as apparently the nasty stuff doesn't cook off.
Joined Jun 27, 2012
IME the onion varieties with the least potent fumes (the sweet yellows mainly) to be more watery with less onion flavor if used in long cooking type dishes like stews and soups.
I use them mainly raw as garnish (reds as well as the 1015) or lightly caramelized.
Anything else has the fisherman asking if I forgot the onion.
Tip..storing onions in the fridge will cut down on the worst of the fumes...

Joined Jan 7, 2018
Great post, this my thought and educated guess on this ... think of the chemistry that happens when you caramelize onions. So maybe start with caramelizing the onions and go from that point. You can make gold out of straw so it would seem you can't make a caramelized onion tasting syrup without caramelized onions first. Just my thought!
Joined Oct 31, 2012
I'd agree with Saucy. Caramelize first, then strain, then reduce.
I love the idea though. I've been meaning to make some powders but haven't made the time. Syrups from various veg would be a very interesting experiment.
Joined Jan 6, 2018
Incoming metaphor. Stay with me:

So I have kind of a love-hate relationship with Facebook. I like keeping up with friends I wouldn't otherwise stay in contact with, even if it is a little surface level. It's nice to know some things about them when you run into them in the bar on trips back to your home town for a visit. I love these people, but some of them are morons. Sometimes, they post the most ridiculous stuff you've ever seen on Facebook. I don't do it any more because I try not to spread discontent, but I always delight a little when someone posts some nonsense about how essential oils MAY fight cancer and someone else posts a link to snopes.com that clearly debunks whatever the easily-duped are raising their eyebrows at that day by citing multiple credible sources.

When this happens (frequently), I imagine sort of a 60s Batman-like graphic jumping out of the screen saying 'SNOPSED!!!" and like a "wanh-wanh" horn noise.

Ok, back to relevancy: Does anyone on this form ever get analogously "McGeed"? Like "Huh. Another food science question. Have you checked McGee?" He should have been my first stop and I feel sheepish I didn't think of it sooner. I'm new here, but I got the impression that Harold McGee was generally regarded as authoritative when it comes to food science or chemistry. Please correct me if I'm wrong.

I'm paraphrasing, but if I understand his explanation right, there are two separate components in an onion cell that, when damaged combine to create the unpleasant but familiar sulfurous aromas onions sometimes have. By sending mine through a masticating juicer, it is almost like I deliberately tried to maximize sulfur production. Maybe that's why it felt like a damn onion bomb went off in my kitchen. I felt a little like Ron Swanson: Grudging tears were shed. But I'll be damned if those tears didn't earn their way out.

Here's where it gets weird, though. McGee says in a couple of places that the sulfurous compounds break down during extended cooking. Mine certainly did not. I'm not sure why I have such a bee in my bonnet about this. Maybe some part of me just really wants to figure out how to make caramelized onion syrup.

I hope it won't be considered a breach of etiquette, but McGee's website curiouscook.com posts an email address for him, so I wrote him an email asking about this last night. It would be super cool if he responds, but even if it gets ignored I'm out all of about 10 minutes of hunching over trying to type an email on my stupid phone.

Think he'll respond?

Latest posts

Top Bottom