I was making a caramel sauce the other day and looked up the melting point of sugar. Different recipes called for completely different temperatures. As it turns out, the "apparent melting point" depends on the rate of heating. If you heat it quickly, it will break down at a higher temperature vs. if you heat is slowly. The key is holding sugar over a low temperature for a longer period of time.
PS- once you melt sugar you can never get the same soild sugar back again b/c it breaks down.
That's sweet of you to tell us that.
Define "sugar"
The sugah in my 'donk only melts when you touch it.
Mr. Obvious wrote:
Define "sugar"
granulated white or unprocessed brown sugar
Make some invert sugar and led it harden. Pretty freaky stuff - like sugar glass.
Or 186 degrees C.
Sugar is not an exact substance. It's got a slightly different atomic make up depending on where it was grown etc etc. That's why there's different melting points.
A simple experiment for you get some water from the tap and boil it, what temperature does it start to boil, I doubt it is 100C. Now add some salt, what temperature now?
Tux Fan wrote:A simple experiment for you get some water from the tap and boil it, what temperature does it start to boil, I doubt it is 100C. Now add some salt, what temperature now?
I performed an experiment to test my theory. I got out 2 small saucepans (same make, type) and added a tablespoon of granulated white sugar (same make, same batch) to each. I set one saucepan on low heat and the other on medium heat then observed the temperature (using a candy thermometer) at which the sugar started to "melt". The sugar on the low heat setting melted at a lower temperature than the sugar on the high heat setting.
Now do you believe me?
You are not accounting for:
You measured the temperature of the water, not the temperature of the sugar.
Water has a noteworthy specific heat capacity. Sugar, I have no idea.
The stove heats the pan/pot, which heats the water, which heats the sugar. There is going to be some lag time, even if it is small. So, it does make sense that the more slowly heated pan would have sugar which melted at a lower water temperature. In the faster-heated pan, the temperature of the sugar might have been the same at its melting point as the slower heated pan, even if the water temperature was different.
It is obviously much easier to measure water heat than sugar heat, so it might make sense that recipes operate this way.
You could try preheating an oven and putting in dry sugar and you might be able to pinpoint a melting point.
What are you talking about? Sucrose is an exact substance. By definition! It has a specific atomic structure and any deviation from that is NOT sucrose anymore!
it may be that cane sugar from different sources has differing amounts of sucrose and other chemicals IN THE EXTRACT which is sold as "cane sugar." And that could affect the melting point slightly. But the rate of heating has no effect on melting point.
Sheesh. Some people need to learn some high school chemistry.
RandomGuy wrote:
You are not accounting for:
You measured the temperature of the water, not the temperature of the sugar.
Water has a noteworthy specific heat capacity. Sugar, I have no idea.
The stove heats the pan/pot, which heats the water...
Water was not added to the pan. Only sugar was in the pan, so therefore the thermometer was measuring the temperature of the sugar.
If water was added to the pan then the water would dissolve the sugar. The idea is to melt the sugar, not dissolve it.
sadfsadf wrote:
But the rate of heating has no effect on melting point.
Then do the experiment yourself and tell me what you find.
I learn something new every day, sometimes even by coming to Letsrun.com.
Apparently sugar does not melt, it decomposes:
http://www.sciencedaily.com/releases/2011/07/110725123549.htm
what's the difference between melting and decomposing?
You can read the article for a better explanation but basically the sugar breaks down into component parts when it is heated. The end result is not sucrose any more.
master chef wrote:
I was making a caramel sauce the other day and looked up the melting point of sugar. Different recipes called for completely different temperatures. As it turns out, the "apparent melting point" depends on the rate of heating. If you heat it quickly, it will break down at a higher temperature vs. if you heat is slowly. The key is holding sugar over a low temperature for a longer period of time.
PS- once you melt sugar you can never get the same soild sugar back again b/c it breaks down.
Did you know that you can't uncooked an egg?
An interesting addition to this discussion.
Adding table salt to water causes the water to boil at a higher temperature.
master chef wrote:
Water was not added to the pan. Only sugar was in the pan, so therefore the thermometer was measuring the temperature of the sugar.
If water was added to the pan then the water would dissolve the sugar. The idea is to melt the sugar, not dissolve it.
I don't like that 1T amount. Too small. Are you sure the sensor point/section of the thermometer was touching sugar?