I got a lot of questions about sodium citrate after posting my foolproof fondue recipe last week. So this week I’m going to dive into the ins and outs of sodium citrate! Below is the chemical formula for sodium citrate, I’m sure you’ve noticed that it spells nacho… which is also my personal favorite way to use it: in ooey gooey, smooth nacho cheese.
What is it?
Sodium Citrate is the sodium salt of citric acid. There are three possible types, monosodium citrate, disodium citrate, and trisodium citrate. The type most commonly found in food is trisodium. Sodium Citrate is the weak conjugate base of citric acid. Basically, if you remove the H+ ion in citric acid and replace it with Na+ ion, you get sodium citrate. It is most commonly sold as a crystalline white powder.
Enough of the chemistry talk, how was it first used?
It was first used in the 1890s as an experimental anticoagulant in blood transfusions for dogs. Doctors Luis Agote of Argentina and Albert Hustin of Belgium both successfully used sodium citrate as an anticoagulant in blood transfusions in 1914. It is still used today in blood collection tubes to aid in the preservation of blood. It is also used in numerous medical applications involving kidney stones, balancing the PH of urine, and the prevention of gout.
Sodium citrate and food.
Sodium Citrate is most known these days for the magical texture it gives to Velveeta and other processed cheeses. It is this synergistic relationship with cheese proteins that I prize it for. In cheese, sodium citrate locks up the calcium that normally causes casein (cheese protein) to curl up and clump. Without any free calcium floating around, casein stays loose and runny. This smooth, creamy texture stays emulsified and allows the cheese to be cooled, reheated, molded, and cut.
The wonders of sodium citrate are not only limited to cheese in the food world. A prominent preservative known as E331, it is also used as a flavoring agent in many beverages, adding an addictive salty tart flavor. It is also commonly used as a PH buffer, which means that it makes a solution more resistant to changes in PH.
Where to buy it and how to use it.
I buy my sodium citrate (and hydrocolloids) from modernist pantry. They have a deep catalog of products and equipment, recipes, and fantastic customer service. (Not sponsored!)
This recipe from Saveur is a good template to start dipping your toes into the world of cheese emulsification using sodium citrate. It's a pretty simple process, the liquid base is heated with the sodium citrate until dissolved, then the shredded cheese is incorporated into the liquid base until melted and emulsified. When emulsifying cheese for either fondue or an “American” cheese, I like to use semi hard or hard cheeses like emmental, appenzeller, comte, muenster, gruyere, or cheddar. You can use runnier cheeses like camembert or brie, but for best results, I wouldn’t use more than 20% of the total weight of cheese.
As a rule of thumb, about 3% of sodium citrate by weight to 100% cheese results in a stable emulsion.
The biggest oversight I see in recipes using sodium citrate is how to disperse it in your solution. Sodium citrate can hydrate at any liquid temperature, but it dissolves much quicker and easier when it is going into a hot liquid. And while some vigorous whisking (about a minute's worth) is enough to dissolve it, I personally think an immersion blender gives you much better results.
Now go forth and create your own dream American cheese! (My personal favorite is a combination of sharp yellow cheddar, appenzeller, and eppoises.)
Hope your new year is filled with lots of cheese!