Spaghetti changes as you cook it: You don't need a fancy degree to understand that. The dried pasta starts so rigid you can snap it in half (with the right technique). If you boil the noodles too long, you'll end up with unenjoyable mush. And somewhere in the middle exists al dente perfection. But what's actually happening here? It's not alchemy—otherwise the instructions on the box would be a lot more complicated. So a couple of pasta-focused scientists from the University of California, Berkeley, decided to break down the physical process a strand of spaghetti undergoes during cooking.
The paper—entitled "Mechanics-based model for the cooking-induced deformation of spaghetti" and published last week in the journal Physical Review E—might sound like an indulgence in the mundane, but the authors—Nathaniel Goldberg and Oliver O'Reilly—believe the results are exciting, if only because they prove that, as spaghetti cooks, it follows a predictable model as it changes. (No more blaming bad luck for your bad pasta!) "We hope it raises awareness of and interest in the marvelous food science and physics in cooking," O'Reilly told me via email.
To determine their findings, the scientists took an unorthodox approach to "cooking," choosing to soak a single strand—chosen at random out of a package of Trader Joe's brand spaghetti—in room temperature water, which made observation of the changes easier. What they uncovered was "a curious three-stage deformation sequence," as the study states: steps they call "sagging," "settling," and "curling." Initially, gravity plays a role as the weakened pasta falls into the water, but as more water is absorbed, the spaghetti becomes "considerably more geometrically complex than its starting state." In laymen's terms, as a strand of dry spaghetti absorbs water the way it changes shape also changes—thus the multiple stages and why cooking spaghetti is a more complicated scientific problem than it may seem.
Admittedly, O'Reilly said the research likely won't have any direct effect for chefs and home cooks, but it could have secondary ramifications. "Our model, coupled with data on the pasta from food scientists in Italy, can be used to quantify variations in the cooking time of spaghetti with changes to the dimensions of a spaghetti strand and water temperature," O'Reilly continued. "In this respect, our work might be useful to the food processing industry."
But back to the cooking process, O'Reilly did offer up one practical finding from their research: Don't cook pasta the way they did. "It made Nate Goldberg and myself appreciate the importance of the starch gelatinization process (which happens when spaghetti is cooked over 50 degrees Celsius) to the flavor and texture of pasta," he told me. "Having sampled pasta that's been cooked at room temperature for over two hours, we certainly would not recommend serving pasta that's been cooked in this manner." Not that we needed science to tell us how to make really bad spaghetti. We figured that out years ago!