Sodium Citrate, a “melting salt”, is the secret ingredient to make any cheese into a smooth, creamy nacho cheese sauce. Coincidentally, Sodium Citrate’s chemical formula spells out Na3C6H5O7 (NaCHO). – WTF Fun Facts
Source: https://www.cooksillustrated.com/science/830-articles/story/cooks-science-explains-sodium-citrate