Hot cheese is a sensual affair. Just consider the delight of watching soft, stretchy strands emerge from between the halves of a grilled cheese sandwich.
Think of the anticipation of stirring a fresh egg and a pat of butter into the warm, cheese-filled center of a just-baked khachapuri But how does fondue β or any cheese sauce, for that matter β stay so fluid?
On its own, melting cheese tends to rapidly morph into an oily, congealing blob. Recently struck with a longing to enjoy the pleasures of dipping salty tortilla chips into spicy cheese but wanting to go beyond the jars of mass-produced products that often fall short on flavor even if the ingredient list seems promising, I decided to learn more about the science of melted cheese.
Specifically, I wanted to learn how to use sodium citrate. With a bag of sodium citrate in my cupboard and myriad cheeses in my refrigerator, I was ready to consult the experts and get to work. The all-too-familiar oiliness when heating cheese is due to fat leaking out of the weakened protein structure. Polowsky notes that a good read: non-oily fondue is the result of a successful emulsion β a stable mixture of substances that normally do not like being combined. With fondue, that emulsifying trickery comes from the tartaric acid that is present in wine.
A squeeze of lemon juice, often added anyway for its bright flavor, can further aid emulsion thanks to the citric acid. These acids function as emulsifying salts [3] , which, as Polowsky explains, induce emulsification by disrupting the tightly knit protein structure and thus allowing for smoother, more cohesive melting.
