さまざまの言葉… random items

January 14, 2008

Super-Simplified Food Chemistry, Part 1

Filed under: food chemistry — rithban @ 6:04 am

Food

Food is the chemicals we eat. This was the most important thing that my Nutrition and Food Science professor wanted us to remember.

We’ve been trained to think of “chemical” as something nasty and harmful. Everything in our physical world is made of chemicals of one sort or another. Pure distilled water is a chemical — H2O — two hydrogen atoms stuck to an oxygen atom.

We should not automatically think of “chemical” as something sinister. Without chemicals there would be nothing physical.

Carbohydrates

Carbohydrates are made out of building blocks called “simple sugars.” Take styrofoam balls. One colour for glucose, another for fructose, another for galactose. Alone these are called monosaccharides. That’s a fancy word meaning “one sugar.”

  • Glucose is very important for life. The body uses this as a package of food and energy for the cells. Plants create it with the help of sunlight. It is not as sweet as the table sugar we’re familiar with.
  • Fructose is common in fruits, berries, and honey. It is almost twice as sweet as table sugar.
  • Galactose is half of “milk sugar” (lactose). It is not very sweet.

If we start sticking monosaccharides together, we get different chemicals. If we stick two monosaccharides together, we form new sugars called disaccharides, which means “two sugars.”

  • Take a styrofoam ball for glucose and a styrofoam ball for fructose. Stick them together. We now have sucrose, or the ordinary table sugar we are familiar with. When we eat sucrose, the body pulls the two balls apart so it can use them.
  • Take a styrofoam ball for glucose and a styrofoam ball for galactose. Stick them together. We now have lactose, a sugar found in milk.
  • pf_whoppers.thumbnail.gifTake two styrofoam balls for glucose. Stick them together. We now have maltose, a type of sugar found in malted milk, including the candy “Whoppers.”

Polysaccharides

Starches and other polysaccharides (“many sugars”) are made from long chains of simple sugars. Take hundreds of glucose styrofoam balls and make a long string of them. This will give an idea of starch. These long chains can stick together, making branches like a tree, or sticking together along their sides.

Here is an example of long chains sticking together:

468px-glycogen.png

Originally written 30 July 2007.

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