Monday, October 3, 2011

You're Burning the Chow

Little John: You're burning the chow!
Robin Hood: Sorry, Johnny. I guess I was thinking about Maid Marian again
- Disney's movie, Robin Hood
When one thinks of school the obvious subjects are Reading, Writing, and Arithmetic. But the two high school classes that I have most benefited from are Typing and Cooking which I use everyday. Cooking class was fun - our teacher acquired bags and bags of apples that fell on a nearby golf course so for weeks we explored many possible ways to cook or bake with apples (yum!)

It is often said that cooking is an art while baking is a science. Cooking follows formulas and requires technique but the flavoring should be done by taste because the seasonings used may be stale and require extra amounts. Baking requires exact measurements and precise cooking time and temperature. Baking uses ingredients that are rather basic but must be combined in the right way - butter, eggs, salt, flour, water, milk, sugar, etc.

For example, if you're making sugary candle like caramel, you'll want to buy a candy thermometer. Sugar is very particular and changes its color and consistency with different temperatures that is well documented in cookbooks.  Because of this I thought the chemistry of sugar was well understood. Imagine my surprise to find out that University of Illinois scientists learn startling new truth about sugar.
"In the literature, the melting point for sucrose varies widely, but scientists have always blamed these differences on impurities and instrumentation differences."
When the Illinois scientists could not get sugar to melt at a fixed temperature, they decided to investigate and learned that the melting point of sugar was heating-rate dependent.
"We saw different results depending on how quickly we heated the sucrose. That led us to believe that molecules were beginning to break down as part of a kinetic process."
When a compound has a fixed melting point, the compound changes phase-state (i.e. from solid to liquid) and that change is reversible because the chemical composition of the compound is unchanged. But some substances (organic ones like milk and now sugar) "melt" by decomposing, by breaking up in to different chemicals in a process that is NOT reversible by merely cooling the temperature. At high heat sugar will decompose rapidly and appear to "melt" at a lower temperature. This is exactly the same as heating milk - if you heat it too quickly it "scalds" and burns. You must heat milk (and sugar) slowly to avoid decomposition.

Bottom Line

What does this mean for cooks? The temperature setting on your stove matters. You can not just set the burner to High to cook something faster. Butter will burn, milk scald, and sugars break down when the heating is too fast.

Experienced cooks also learn that more heat does NOT boiling pasta faster-  the water will stay at boiling temperature (100 C or 212 F) and go no higher. You can use High to get the water to boiling quickly, but once there, you're wasting energy if you don't turn it back to Low. All high heat does during boiling is turn more water to steam - it won't make the water any hotter.

Nine women can not produce a baby in one month
- The Mythical Man-Month

"all things come to those who wait"

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