When it comes to the serious business of curing, the simple fact is that salt blocks often provide the technically superior way to get the job done. Sometimes they are the only way to get the job done.
There are two basic categories of salt block cures: partial cures, where the salt draws out a modest amount of moisture and increases the salinity of the food just enough to improve its texture and taste while extending the life of the food; and full cures, were salt is brought into greater contact with the food to draw out more moisture and raise salinity further to create cures that can last long periods of time with proper storage. With a quick cure no more than 10% of the food’s moisture will be lost. With a slow cure, upwards of 30% of the moisture may be lost. Gravlax is an example of a quick cure, and beef jerky is an example of a full cure.
There are limits what you can cure with salt blocks. Fermented cures like sausage are not possible because they would allow neither the necessary distribution nor the controlled quantities of salt. In fermented cures salt effectively provides the first line of defense against unwanted bacteria such as salmonella, but still allows growth of helpful bacteria that increase acidity (lower pH) enough to inhibit the growth of very hearty, very dangerous bacteria like Clostridium botulinum (food poisoning).