Spaghetti Science

Ever run out of soup noodles and relied on breaking up spaghetti into small 1 to 2 cm pieces? That’s what I just did, and I never realized how many 1-2 mm fragments are generated with each and every break. In fact some bits were even smaller than a millimeter. I realized it by fluke because I was breaking the spaghetti with my hands inside a strainer, and the “dust” trickled through the sieve’s 3 mm holes, decorating the counter top. Here’s what it looked like.

It turns out that this has been common knowledge. Scientists have looked into it as well. According to a Smithsonian article,

To break it requires bending it into a bow shape. Eventually the force of the bend snaps the rod in the middle where it is most curved. But the physics doesn’t end there. That break releases energy back down the pieces of spaghetti in a “snap-back” wave or vibration. There’s enough energy in those waves to break off smaller lengths of pasta.

Jason Daley August 16, 2018

If you first twist the spaghetti, apparently, the “twist wave” travels faster than the snap, dissipating its energy. And the spaghetti breaks cleanly. But it would have taken a lot of impractical twisting in my case, given that I broke each strand several times while clumping several strands together to break them faster.

What goes on when spaghetti cooks? The chemistry part.

There are basically two parts to the process occurring between 55 and 85 oC. Water moves into the starch granules, causing them to expand. But for the pasta to fully cook, its protein has to react. If you have egg noodles, an insoluble network of egg and flour proteins form, trapping the swelling starch granules. A pH of 6, according to molecular gastronomist, Herve This, helps the proteins bind the starch even more firmly. One year I had my students test this notion by acidifying the boiling water with a tablespoon of lemon juice. Surely, enough it prevented the pasta from becoming sticky.

What if you have regular noodles? The same thing happens to the starch. But heat converts the flour’s globular proteins into relaxed chains. If overcooked the chains don’t trap the expanding starch, and its amylopectin diffuses out. As it clings to the surface of different strands, it binds them together. You end up with messy lumps of spaghetti.

Oddly, it never takes me the 10 minutes of recommended cooking time. Five seem to be sufficient to create a slightly al dente spaghetti. What’s also noteworthy is how the same recipe but different shapes of pasta creates a different taste, probably because of the role that texture plays in taste and because different shapes have different surface to volume ratios. Thus varying amounts of sauce cling to each noodle.

Recent research (2021) at the University of Parma in Italy confirmed that pasta is a medium to low-GI food, (glycemic index = GI). That’s related to the fact that the starch granules remain trapped in the network, and so they are not completely hydrolyzed in the small intestine. The GI was lowest for those pastas that were enriched with legumes or other plant based products.

Sources:

Herve This. Molecular Gastronomy. Columbia University Press. 2006

Exploratorium. Soaking Pasta. https://www.exploratorium.edu/food/soaking-pasta

Jason Daley. Physics Reveals How to Break Spaghetti Cleanly In Two. Smithsonian. 16/08/2016

Giuseppe Di Pede and al. Glycemic Index Values of Pasta Products: An Overview. Foods 202110(11), 2541; https://doi.org/10.3390/foods10112541

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