Short answers, pulled from the story.
Food curing is a group of preservation processes that use salt, nitrates, nitrites, smoke, sugar, or combinations of these to make food inhospitable to microbial growth. Salt draws moisture out of the food through osmosis, reducing the water available for bacteria to survive. A salt concentration of close to 20 percent is required to slow microbial growth effectively.
Cured meat turns pink or red because nitrite compounds, typically sodium nitrite or potassium nitrate, bond to myoglobin in the meat and act as a substitute for oxygen. Nitrite breaks down into nitric oxide, which binds to the iron atom in myoglobin's heme group. When cooked, this produces the characteristic pink color known as nitrosyl-heme.
Yes. In 2015, the World Health Organization's International Agency for Research on Cancer reviewed more than 400 studies and classified processed meat as a Group 1 carcinogen, meaning it causes cancer in humans. The WHO estimated that eating 50 grams of processed meat per day raises the lifetime risk of bowel cancer by 18 percent.
Curing salt is a mixture of table salt with nitrates or nitrites, most commonly sodium nitrite or potassium nitrate. It is dyed pink to prevent it from being confused with ordinary table salt. Neither table salt nor the nitrates and nitrites used in curing are naturally pink.
Not necessarily. A 2019 Consumer Reports investigation found that many products labeled "uncured" or "no nitrates or nitrites added" used celery as an ingredient, which contains naturally occurring nitrates and nitrites. The USDA permits this labeling, which Consumer Reports and the Center for Science in the Public Interest argued gives consumers a false impression of a healthier choice.
Curing can be traced back to antiquity and was the primary method of preserving meat and fish until the late 19th century. Ancient sources including Diodore of Sicily and Strabo document the salting of meat in the ancient Mediterranean world. By the time of Polybius, roughly 200 to 118 BCE, the Gauls were already exporting large quantities of cured pork to Rome.