One site says"...faced with preserving fresh meat for the winter season, butchers would routinely pack beef or pork products in salt to prevent the formation of bacteria and mold. Meats like beef brisket could also be pickled in a spicy, salty brine. At one time, the word corn referred to a number of kernels or seeds, including the coarse salt granules packed around the brisket. Thus the meat was called 'corned' beef in reference to the corns of salt."