"Hershey process" milk chocolate is popular in the US. The process was invented by Milton S. Hershey, founder of The Hershey Company. The process uses fresh milk from local farms. The logistics of purchasing and delivering fresh milk is difficult as, according to state regulations fresh milk cannot be held for more than 72 hours after its reception. If not immediately processed into milk chocolate, the milk must be disposed of. The actual Hershey process is a trade secret, but experts speculate that the milk is partially lipolyzed, producing butyric acid, and then the milk is pasteurized and stabilized. This process gives the product a particular taste, to which the US public has shown to have an affinity, to the extent that some rival manufacturers now add butyric acid to their milk chocolates.
Dark chocolate, also known as"plain chocolate" or "black chocolate", is produced by adding fat and sugar to cocoa to a lower proportion of milk or sometimes none at all. The U.S. has no official definition for dark chocolate. Dark chocolate can be eaten as is, or used in cooking, for which thicker, baking bars, usually with high cocoa percentages ranging from 70% to 99% are sold. Dark is synonymous with semisweet, and extra dark with bittersweet, although the ratio of cocoa butter to solids may vary.