onion caramelization

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Can someone explain to me exactly what is going on when onions get "caramelized". Caramelization of onions is done with VERY slow cooking and while it renders the onions somewhat brown, it is very different than just "browning" the onions, which can be done fast. It is often said that caramelization is about releasing sugars from the onions, which doesn't seem quite right, since the taste of caramelized onions is supremely better than regular cooked onions. Something is chemically changing. Releasing sugar isn't going to do that, because before they are carmelized, the sugar is still in the onions. I am assuming that it might have to do with oxidation of those sugars, and perhaps also concentration of flavor by cooking off a lot of the water. Some chemical background would be appreciated. Also, to the extent it is about sugar, what is the sugar in onions? Fructose? Sucrose?
 
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You should read Harold McGee's book, "On Food and Cooking" if I remember correctly. Otherwise I'll suggest you're over thinking the whole thing.
Yes, the sugar and juice from the onions is released and eventually caramelizes. If you brown the onions fast, you get some caramelization but mostly browned onion.. Slow cooking allows time for more juice/sugar to be released by the extended heat time breaking down more cell walls. You end up getting the caramelization and the Maillard reaction at the same time which is why they shrink so much but they taste so much better. And they should be quite brown when finished.
 
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But onions don't have a lot of sugar. I can brix them, and they come out pretty low. Sweet onions, BTW, aren't sweet. Their sweetness isn't about sugar. It's about mildness. My understanding now is that onions do have complex sugars, that don't register in brix and don't taste sweet, and that serious cooking breaks them down into less complex and sweet sugars. That's what finally makes them sweet. Caramelization is sort of a byproduct of that. Caramelized sugar isn't sweeter than sugar. Let's not under think the whole thing.

BTW, I think the Maillard reaction is just what makes the onions brown. It's not about breaking down sugars. I can brown onions without caramelizing them.
 
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Just FYI, there is an excellent chemical description of caramelization (which can be applied to onions) in https://www.eufic.org/en/food-safety/article/the-why-how-and-consequences-of-cooking-our-food
(scroll down about a third of the way .. this is a long essay), and distinguishes it from the Maillard reaction.
With onions, complex carbs (which are actually chains of sugars) are broken down into simple sugars by extended cooking. What is just implied in this piece is that the sucrose actually is produced by breakdown of these complex carbs. The sucrose then degrades into monomer sugars, like glucose and fructose. All taste sweet.
 
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Of course onions have sugar in them. After a lengthy cooking process they darken—turn golden/reddish/brown. That’s not from oxidization, that’s from caramelization.

How do you get 40% alc. whiskey from a mash that has max. 16-17% alcohol? You remove the water.

True, onions don’t have a lot of sugar, but they do have a lot of water. As others have stated, with a lengthy cooking process you break down the cell structure, release (and evaporate) a lot of water, reduce the volume dramatically, and by doing so, concentrate the flavours. What little sugars are in the onion will caramelize..

For me, browning an onion is a aptly that—cooking it until it turns a golden reddish brown. This takes time—anywhere from 25-40 minutes. Quickly cooking an onion until it’s soft and translucent but has no colour is—for me and most of the professional cooking community—is known as “ sweating” an onion.

Hope this helps
 
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They've got very little simple sugars. I've brixed them out. Not much there. The point of caramelization is that simple sugars are PRODUCED from the complex carbs that they have a lot of. No, if you just dry out an onion, it won't be sweet by flavor concentration. Have you ever dried onions? I have. Hope this helps.

I can brown onions in five minutes on high heat. But that doesn't apply the heat that is needed to break down those carbs. Browning onions is not the same as caramelizing them.
 
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What is it exactly what you’re looking for?
An explanation on why onions turn brown after a lengthy cooking process?
Only two explanations: Either oxidization or caramelization.. And as you well know, onions unlike apples do not oxidize.

Sugar, when exposed to heat will turn brown. When exposed to a lot of heat it will turn black—something that Coca-cola and every distillery ( and food producer) in the world takes advantage of.
 
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What was I looking for? Please read my original post. I found what I was looking for, and didn't get it here. I've left you all with the answer, in case you're interested. But thanks anyway!
 
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Not really,

re reading your post it sounds like you refuse to acknowledge that “ caramelization” is the very simple process of turning sugar brown with heat. Many foods contain sugar, which is why many foods brown when exposed to heat.

You refer to “ brixing.” several times in your posts. I had assumed ( wrongly) that you had a background in the wines and spirits industry or in confectionary. You do acknowledge that onions do contain small amounts of sugar—which I did state in my second post. I also stated that onions have a high water content— which is why they take so long to cook down, and since the sugars cannot evaporate with the water, they will caramilize.

Dehydrated onions ( granulated or in flake form) are very commonly obtained in any food store. Try a taste test — they are sweet.
 
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Not really,

re reading your post it sounds like you refuse to acknowledge that “ caramelization” is the very simple process of turning sugar brown with heat. Many foods contain sugar, which is why many foods brown when exposed to heat.

You refer to “ brixing.” several times in your posts. I had assumed ( wrongly) that you had a background in the wines and spirits industry or in confectionary. You do acknowledge that onions do contain small amounts of sugar—which I did state in my second post. I also stated that onions have a high water content— which is why they take so long to cook down, and since the sugars cannot evaporate with the water, they will caramilize.

Dehydrated onions ( granulated or in flake form) are very commonly obtained in any food store. Try a taste test — they are sweet.
I agree with everything you state here. Onions do, in fact, contain sugars and water. The slow and low cooking of onion does caramelize, which by definition, is the breakdown and the reaction if sugars to heat. It is what caramelization is.

You did NOT misunderstand the OP, nor was your replies incorrect in any way.

Sweet onions are milder... and sweeter. That is why they are called "sweet onions". Vidalia onions fall into this category, for example and do contain a whopping 12.5% sugar. That's more natural sugar than is found in apples. In fact, for this reason I do not use Vidalia's in dishes which need to be more savory.

I do understand your entire explanation. I have trouble with some of the things in the OP's questions and understandings of basic cooking.
 

kuan

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First of all, you don't need very much sugar at all. All you need is the little bit of sugar to coat the onion and caramelize. Next The starch in the onion begins to break down into sugar. This is the main source of caramelization.
 
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Kuan,

If you go to the O.p’s history and look at his posts, you’ll notice a definite pattern: Dude asks a question and then promptly argues with anyone that responds.

As the Scots would say “ don’t let the door hit you on the way out”....
 
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Kuan,

If you go to the O.p’s history and look at his posts, you’ll notice a definite pattern: Dude asks a question and then promptly argues with anyone that responds.

As the Scots would say “ don’t let the door hit you on the way out”....
Indeed, one needs only looking at a few of his topics to conclude he's a troll.
 
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