Sugar Melting Point Varies Because Sugar Doesn't Melt; It Decomposes

Melting sugar for candy always feels like a vaguely arcane process. You put the raw white sugar in a pan, turn up the heat, and wait for something to happen. Sometimes it goes fast, sometimes it takes forever. There are guides to the different stages it passes through before becoming caramel, but they're horribly confusing. (Soft ball, hard ball, crack... who can tell the difference?).

Home cooks, apparently, aren't the only ones who have been mired in confusion. Different scientific sources have disagreed wildly on the exact melting point of sugar for ages. Some say 140 degrees Celsius, some say 160. A new study on sugar melting from Shelly J. Schmidt of the University of Illinois may provide an explanation.

The sugar melting study showed that the reason scientists and cooks haven't been able to isolate a definitive melting point for sugar is that sugar doesn't melt—it decomposes. This means that, rather than melting at one definitive temperature, sugar can become a liquid at different temperatures depending on heating rate. If you heat sugar quickly, using extremely high heat, it will melt at a higher temperature than it would if you heat it slowly, using low heat.

Everyone had assumed that sugar behaved like crystals and metals, which have the ability to melt and re-solidify at a definitive and predictable temperature. But Schmidt's new study puts sugar in a category closer to other complex organic compounds like wood and paper, which break down into simpler compounds, like carbon dioxide and oxygen, before they "melt." So there is no such thing as liquid sugar, just as there is no such thing as liquid cardboard.

The study's real-world implications are to be determined. But candy producers and sugar artisans, armed with this new scientific knowledge, may be able to push their craft in unforeseeable directions.

Comments

[gypsysailor]

06:28 AM on 08/01/2011

All of that is interesting but have the researchers taken into account that not all sugar is made from the same plants? There is cane sugar, beet sugar, aguave sugar and some I'm sure I have not heard of. In each case the sugar is made from a different plant and so should have a different degree of either melting or decomposing.

[Daybot]

01:49 AM on 07/30/2011

A "new" study with old information. By the look of some of the comments posted, some people need a refresher course in chemistry.

[LXIX WITHU]

12:18 PM on 07/28/2011

There are guides to the different stages it passes through before becoming caramel, but they're horribly confusing. (Soft ball, hard ball, crack... who can tell the difference?).

I always wondered where crack came from.

[joellen835]

04:48 PM on 07/28/2011

the answer to "who can tell the difference" is...........a good candy thermometer.

[Prairie Girl 6]

12:18 PM on 07/28/2011

Only thing I care about is the decomposition of calories. Do they go away when sugar is heated?

[joellen835]

04:48 PM on 07/28/2011

wouldn't that be great!!!!!!!!!

[msllsa1]

11:24 AM on 07/28/2011

WHA????

[knarf714]

10:33 AM on 07/28/2011

What is shocking about this? Another variable s tha amount of moisture in the sugar, the more moisture, the longer it takes to break down.

[angelgirl41181]

10:26 AM on 07/28/2011

Most of these comments are from ignorant people who have never taken an organic or inorganic chemistry course in their life. They have no clue what they are talking about.

[natal plum]

10:52 AM on 07/28/2011

Okay, I'm game, what are they talking about? Give us some clues please I don't need to have taken a chemistry course to know what happens when certain compounds are exposed to varying degrees of heat.

[angelgirl41181]

11:16 AM on 07/28/2011

Do you know the molecular formula for sucrose, fructose, glucose and mannose, including their enantiomers, chirality, and isomers, or the fact that there are varying open chain and cyclic forms without looking it all up? Each behaves differently.

[360Dunk]

10:53 AM on 07/28/2011

I'm reducing my carbonated beverage footprint after reading your post.

[leslie101]

10:00 AM on 07/28/2011

Let me get this straight, if you heat sugar quickly, using extremely high heat, it will melt at a higher temperature than it would if you heat it slowly, using low heat.

[charpist5]

09:50 AM on 07/28/2011

If you heat sugar quickly, using extremely high heat, it will melt at a higher temperature than it would if you heat it slowly, using low heat.

So they are saying: If you use high heat, the sugar gets hotter. lol lol lol Takes a rocket scientist to figure THAT one out.

[Dewpepis]

10:14 AM on 07/28/2011

Does boiling water get hotter if I use high heat too?

[walkingwolf]

09:20 AM on 07/28/2011

If I get to hot--I'll decompose too..so whats the point?

[patardugno]

07:30 AM on 07/28/2011

Sugar, in sugar cane is a liquid. Then they squeeze it out & let it crystalize. Did they start with sugar cane, or sugar crystals, & would they come to different conclusions if the started with sugar cane? How about sugar beets? If they start with the raw sugar source & do their experiments, what findings would they note? Ut oh, back to the old drawing board! This could take years.

[Dewpepis]

10:13 AM on 07/28/2011

Sugar in sugar cane is a liquid solution where its sugar has been dissolved in water. Liquid sugar is different from that. They most likely started with a purified sugar sample that was 99.99% sucrose or something like that. The difference between sucrose from beets and from sugar canes is very small. They just differ in their carbon isotope ratios. Chemically they should behave the same.

[speedynutrino43]

07:25 AM on 07/28/2011

I remember watching my Grandmother making candies including varous caramel confections. I wonder how much time she spent pondering the "decomposition" of sugar. I don't recall but living near the Gulf of Mexico, she probably avoided divinity in hot, humid conditions which were the predomionant weather pattern in south Alabama except for December, January or February.

[patardugno]

07:24 AM on 07/28/2011

Simple syrup is a form of liquid sugar. You don't need to melt sugar to make is liquid, just add water, oh sorry H2O. Sorry, but like those ladies in the south pointed out, we know that when cooking there are many variables about different things, like high altitude cake baking, or hard water problems. Do those chemists really think something new has been discovered, .....or just that they learned something new. Because there is a difference between those 2 things.

[Dewpepis]

10:16 AM on 07/28/2011

They aren't talking about variables like that, but the physical and chemical processes that the sugar goes through as it "melts". Those variables that you are talking about are pressure and purity variables and that is an entirely different story.

[natal plum]

07:19 AM on 07/28/2011

This just in. The instant coffee I put into hot water every day doesn't melt - it dissolves. Semantics is a wonderful thing.

[emeathead45]

07:27 AM on 07/28/2011

NO!--It decomposes in your hot water.---lol

[Catherine Girod]

08:38 AM on 07/28/2011

melting and decomposing are not the same.

[natal plum]

09:07 AM on 07/28/2011

Melting, decomposing, dissolving, dissipating, disseminating, distilling, distorting and disappearing under heat and any other variation I can think of - it all melds into something else.

[TERPMOM]

06:39 AM on 07/28/2011

Not all sugars are alike.....PURE CANE sugar is diferent in that it is natural....now the store brand is more than likely .... GENERIC, and has other fillers. (It doesn't beat DOMINO in price for no reason). I've had SOME of the "grains" when boiling melt faster than others. Because of this,
your candy can be half-boiled. Too gritty part wise and well on it's way to syrup the other. If you try to "hang in there" for it ALL to be desolved....better get a spoon and prepare to scrape the pan...no other way to eat it.