Consider kosher salt: large, flaky, white grains that dissolve slowly in cooking. If you like to cook, you probably have a box of Morton or Diamond kosher salt in your cupboard, and if you are a chef, a small mountainous peak is likely sitting in a crock that you keep within arm’s reach in the kitchen at all times. It is one of the most ubiquitous ingredients in the cooking world — but it’s also one of the most misunderstood: All salt can be kosher (if it’s produced under kosher supervision) but not all kosher salt is kosher.
Salt has been used since ancient times to preserve food, and Jews have used it since the time of the Temple to remove blood from meat or “kasher” it, according to Gil Marks, author of the “Encyclopedia of Jewish Food.” Specifically large-grain salts were used as they could be washed from the meat’s surface without making it too salty.
Despite its status as a luxury product elsewhere in the ancient world, this type of salt was abundant in ancient Israel. The salt mines and salty seas of the region helped establish it as a center of the salt trade.
The term “kosher salt,” however, is a 20th-century American construction. “Jews were obviously using the product long before,” Marks said. “It’s not really ‘kosher salt’ — it’s koshering salt.” Up until the 1950s (when packaged kosher meat became available) kosher-keeping home cooks purchased this coarse salt to use in their kitchens to remove blood from the meat they served to their families.
The word came into public consciousness when companies sought to cash in on the wave of Eastern European Jews who immigrated to the U.S. at the end of the 19th and beginning of the 20th centuries. At the same time, the American market moved from purchasing their ingredients (including salt) by the pound, out of large barrels, to buying packaged goods that started appearing on the shelves after World War I.
“Certain companies started marketing to Jews,” Marks explained. At first these were Jewish companies, including Rokeach and Manischewitz; later, non-Jewish companies, including Diamond and Morton, picked up on the trend.