What many home cooks throw away without thinking twice may, after all, be the most valuable ingredient in the kitchen.
Perhaps the reader didn’t know, but the water in which the pasta cooks is loaded with starch and plays a decisive role in the texture and flavor of sauces. The cloudy appearance is not dirt: it is the starch released by the dough during cooking.
Science helps explain why. A study distinguished with an Ig Nobel Prize in Physics (which rewards inventions that may seem ridiculous, but are in fact the product of research by scientists) how water and starch solutions undergo a transformation when heated, changing their viscosity and structure.
This behavior is precisely what makes pasta water so useful in the kitchen. As the pasta cooks, the starch molecules swell and pass into the water, creating a thick, functional liquid.
For the food scientist Abbey Thielspecializing in emulsions, pasta water is much more than “starch water”. It works like a true technical ingredient: it thickens, stabilizes and helps fats and water to stay mixed, resulting in creamier, more homogeneous sauces that adhere better to the pasta, reveals to .
Everything revolves around the emulsions — mixtures of two liquids that normally do not combine, such as olive oil and the water present in tomatoes or wine. Without help, the fat separates, water accumulates and the sauce “opens”. The starch in the pasta water solves this problem in two ways: it makes the liquid thicker, making it difficult for the fat droplets to come together and separate, and it surrounds these droplets like little “coats”, keeping the emulsion stable and silky.
In practice, this is what happens when you finish the dish “Italian style”: the pasta is sautéed for a few minutes in the sauce, along with a ladle of cooking water. The starch stabilizes the mixture of fat (olive oil, butter, cheese) and water (from the dough and other ingredients), creating that shiny and uniform coating typical of a restaurant.
Tests carried out by gastronomic journalist Daniel Gritzer, from the website Serious Eats, confirmed the effect: pasta finished in sauce with cooking water, especially the one richest in starch, formed visibly more connected sauces than those made with just tap water.
The recommendation is simple: Before draining the pasta, always reserve one or two cups of water from the pan.. Ideally, use a slotted spoon or tongs to transfer the pasta directly to the skillet with the sauce.
