While fondue fever in the United States has died down since the 70s, researchers at ETH Zürich have studied what makes the best mixture for this comforting Swiss staple and published their findings in the January issue of ACS Omega. The research, reported on in outlets such as Indie Science, Economic Times, and News-Medical.Net, found the traditional Swiss dish is a complex multiphase system composed of colloidal ingredients. Pascal Bertsch, Laura Savorani, and Peter Fischer studied how altering the ratio of those ingredients affects the rheology or flow behavior of the final product.
They found that within the typical mixture of wine and Gruyère and Vacherin cheeses, starch levels much be at a minimum of 3% of the total weight to produce a homogenous mixture with an ideal flow rate. This flow rate determines not only the texture of the fondue but also its flavor and ability to cling to bread. If you have ever lost a cube of bread in a too think fondue, or pull it back out of the pot with much of the cheese missing, you know that the ideal viscosity of fondue is an essential part of what makes it an iconic dish.
The researchers also noted a surprising side effect of another ingredient added by many Swiss cooks: Baking soda. While the prevailing kitchen wisdom was that adding sodium bicarbonate improves the texture of a fondue by producing bubbles, the research suggests it actually creates creaminess by increasing the mixture’s pH.
“There is no bigger shame in Switzerland than serving a fondue that is too liquid, gummy, or even phase-separated, and many myths without scientific base persist in Swiss kitchens on how to prepare the perfect fondue,” the authors write. Thankfully, cooks the world over can now benefit from their diligent research.