grains), and similar products keep uncooked
for many months.
Useful Impurities: Nitrates and Nitrites
Sodium chloride is not the only salt with an
important role in salt-curing. The others were
unpredictable mineral impurities in the rock,
sea, and vegetable salts originally used for
curing. One of these, potassium nitrate
(KNO 3 ), was discovered during the Middle
Ages and named saltpeter because it was
found as a salt-like crystalline outgrowth on
rocks. In the 16th or 17th century, it was
found to brighten meat color and improve its
flavor, safety, and storage life. Around 1900,
German chemists discovered that during the
cure certain salt-tolerant bacteria transform a
small portion of the nitrate into nitrite (NO 2 ),
and that nitrite rather than nitrate is the true
active ingredient. Once this was known,
producers could eliminate saltpeter from the
curing mixture and replace it with much