How To Avoid Boil Over When Cooking Pasta

There are a couple of reasons why water in a pot will boil over and they have to do with two things: heat and proteins. When you put pasta in boiling water and let it continue boiling over high heat, you may notice that after a while the water boils up and over the edges of the pot in a big foamy mess. This is because the pasta has created a "foaming boil" instead of retaining a "rolling boil."

When plain water boils by itself, the bubbles rise from the surface area of the boiling pot and then break at the surface of the water. This is because water doesn't have enough surface tension to hold back the explosive force of the bubble coming to the surface. However, when you add pasta to the water, organic material in the form of proteins and starches come off the pasta and mix with the water. The starches increase the surface tension of the water, making the surface bubbles stretchy and pliable. This stretching increases the amount of time it takes for a bubble to burst.

The resulting cascading effect causes a "foaming boil" whereby bubbles stack under more bubbles that take too long to burst. Eventually, the stack of foam rises above the lip of the pot and over the edge.

Boil over.

How To Avoid Boil Over
One camp of thought suggests that you put a little bit of oil or margarine into the water. This is proven to prevent boil over. The oil molecules interfere with the surface tension of the starchy bubbles and they break faster. The only problem with this method is that the oil will coat the pasta and whichever sauce you use will not stick. This is considered bad form in most cooking circles, so be careful you don't do it in front of someone who takes is so seriously.

The other method to avoid boil over is just to pay attention. OK, that's a little bit simplistic. This method involves a two-pronged attack. When you add your pasta and it begins to come back to boiling, reduce the heat just a little bit. This reduces the rate at which the bubbles come to the surface, giving them more time to burst before more come up. Also, when the pasta returns to boil, stir it for a minute. This will keep the noodles from sticking together as well as give you time to monitor the boiling.

So there you go, kids. A little science lesson on the dreaded pasta boil over. You can use a little oil to avoid boil over, but only do that if you aren't that concerned about sauce stickage. But my suggestion is just to stir and reduce heat.

Edit: Geneve mentioned that there is a device you can actually place inside the boiling water to prevent the boil over. This is true, it does exist. Click here to see one.