Process cheese is an industrial version of cheese that makes use of surplus, scrap, and unripened materials. It began as a kind of resolidified, long-keeping fondue made from trimmings of genuine cheeses that were unsaleable due to partial defects or damage. The first industrial attempts to melt together a blend of shredded cheeses were made at the end of the 19th century. The key insight—the necessity of “melting salts” analogous to the tartaric acid and citric acid in a fondue’s wine or lemon juice—came in Switzerland in 1912. Five years later, the American company Kraft patented a combination of citric acid and phosphates, and a decade after that it brought out the popular cheddar look-alike Velveeta.