Terlizzi and his co-author, both living overseas, often gather for dinner where they share a passion for Italian cuisine. Cacio e pepe stands out as a favorite dish, prompting them to delve into the underlying physics of its preparation. Their exploration was driven, in part, by a desire to optimize the use of pecorino cheese, as Terlizzi explained. The focus of their research is the separation that occurs when cheese is combined with water, building on previous culinary studies.
While pasta cooks in boiling water, it releases starch, an integral part of the cooking process. Traditionally, chefs remove some of the starchy water and cool it to a temperature that prevents clumping of the cheese proteins during mixing. The cheese is then incorporated, with freshly cracked pepper added just before serving. However, the authors emphasize that temperature is not the sole contributor to the notorious “mozzarella phase” of cheese clumping.
They reveal that mixing cheese with pure water tends to exacerbate clumping. In contrast, using water that contains a bit of starch, such as the water leftover from cooking pasta, mitigates this issue. Their findings suggest that using “risottata,” pasta water that is collected and heated until a higher starch concentration is achieved, yields almost no clumping when mixed with cheese.
Effect of trisodium citrate on the stability of cacio e pepe sauce.
Credit:
G. Bartolucci et al., 2025
The pivotal role of starch in the preparation of cacio e pepe guided the authors in designing a series of experiments to systematically analyze the phase behavior of water, starch, and cheese across various concentrations and temperatures. Equipped with standard kitchen tools, they aimed to ensure that their findings could be replicated by home cooks, despite some requiring specialized equipment like sous vide machines. This experimentation led to the creation of a phase diagram illustrating the behavior of the sauce under different conditions.
