So, what's the science behind pre-cooking pasta? It all comes down to the starches in the pasta. When you cook pasta, the starches absorb water and gelatinize, making the pasta soft and tender. But, if you pre-cook pasta, the starches can break down and make the pasta mushy.
Prep Perfect Pasta: Easy Make-Ahead Cooking Tips For Busy Days | CyPasta
But, don't worry, there are ways to prevent this from happening. You can try shocking the pasta in an ice bath after cooking, to stop the cooking process and preserve the texture. Or, you can use a pasta cooker with a built-in timer, to ensure your pasta is cooked to perfection.