Pasta

If I recall, two weeks ago I began talking about cooking – and its relationship to science. Cooking is like the fun science. And those experiments that produce excellent results…we can eat!
Anyways, I don’t know exactly where to start…

Pasta:
For those who actually cook in the home, I am sure one of the basic foods to become familiar with is pasta* (or noodles). Have you ever been told to add oil to the boiling water – whether in a recipe or by your grandmother (or other cooking instructor)? Sure you have! But why – why add oil?
Some chefs claim that by adding oil to the boiling water, they will help prevent the pasta noodles from sticking together during the cooking process. And this would make sense; oil makes the surfaces of objects slippery and lubricated. There is just one problem – oil floats above water. That is because water molecules are not as attracted to the oil molecules as much as they are attracted to each other, so the water would rather make bonds with other water molecules than oil. Thus the oil floats atop the water.

Although it is not exactly an experiment with laboratory standards, if one were to take 1 gallon of boiling water and add 1 tablespoon of oil with a half pound of pasta noodles and cook until al dente (lit. Italian to the tooth), about 85% of the oil would remain in the original pasta water. That means 15% (around a half teaspoon) of oil has managed to either be adhered to the pasta or temporarily be attracted to the water. In any case, is it reasonable that only half a teaspoon of oil is sufficient to lubricate enough of the half pound of pasta to prevent it from sticking? Adding more to the water would just be a wasteful use of oil. So…why have chefs said for centuries to add oil to the cooking pasta?
If it isn’t to prevent sticking, then why do it?

Pasta is composed of wheat flour, water, eggs, and salt at its most basic. By boiling the pasta, some excess starch from the flour is washed away from the noodles (this is why the pasta water is murky after cooking). This changes the surface tension of water – a property that pulls water molecules together at the surface. As more starch is released into the water, the surface tension becomes so weak that bubbles from the boiling process start to stack on top of each other.

This effect is similar to the foam you see when you go to a beach on a windy day, or the which foam that trails behind motor boats. The only difference is that the foam on the ocean is produced by proteins, while this particular example of pasta is produced by starch.

By adding oil to the pasta water, you add, not lubrication to the actual pasta molecules, but you lubrication to the starch molecules which compose the bubbles. No bubbles, no foam

However, the more practical approach to preventing foam build-up is not adding more oil, but adding more water. By adding more water and using a bigger vessel you (a) give more room for the pasta to move, which in turn yields to a more even cooking. This gives room for the pasta starch to dissipate. Also, the pasta will cook for a shorter period of time in more water (and by adding salt, which will be discussed in another blog). When the pasta is introduced to the water, the temperature of the water drops depending on the amount of water. The more water there is, the more energy there is in the pot, and less rebound time for the water to return to a boil.

To picture this a bit better, let’s consider two extremes. There is one small saucier with two cups of water and another stock pot with two gallons of water, both at a rolling boil. If I were to drop a several ice cubes into each vessel, which pot of water would return to a boil faster – two cups or two gallons?

The pot of two gallons of water, of course –
In this sense, the more water, the faster time it takes to re-boil, the faster cooking time leads to less starch. And if you’re going to be cooking in such a large amount of water, you’re probably going to use your largest pot.

A good rule of thumb: when cooking pasta, use at minimum a half gallon (for one to two servings) of water at a rolling boil. If you are planning on cooking more, use at least one gallon, maybe two. If planning to cook for more than five servings, consider more than one cook cycle (that is, cook in batches) and always leave at least three inches of headroom at the top of the pot to allow for excess starch collection.

*Please take caution when using the stove, oven, sharp instruments (knives, graters, micro-planks, cooking shears, blender, food processor), and take caution in unfamiliar kitchens. The kitchen is a dangerous place.