Thanks for your input, Firefox7275. I was inspired to check Wikipedia for information on food processing, and it offered a rather nuanced view point, although the article on Food processing was thought to be biased. There is also an article on Convenience food, which apparently is also called tertiary processed food, and it mentions things like long shelf-life, i.e., preservatives and other food additives. Wikipedia offered no definition of tertiary processed food, but I found one on glosbe.com: Food so prepared and presented as to be easily and quickly ready for consumption.
You specifically mentions nitrates and nitrites, which I also checked. I compiled the following info from the two articles on nitrate and nitrite (my editing):
According to Wikipedia, nitrates are reduced to nitrites in the saliva. A rich source of inorganic nitrate in the human body body comes from diets rich in leafy green foods, such as spinach and arugula. The use of nitrite for curing meats goes back to the Middle Ages, and in the US has been formally used since 1925. Because of the relatively high toxicity of nitrite (the lethal dose in humans is about 22 milligrams per kilogram of body weight), the maximum allowed nitrite concentration in meat products is 200 ppm. At these levels, some 80 to 90% of the nitrite in the average U.S. diet is not from cured meat products, but from natural nitrite production from vegetable nitrate intake. Under certain conditions – especially during cooking – nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens. However, the role of nitrites (and to some extent nitrates) in preventing botulism has prevented the complete removal of nitrites from cured meat, and indeed by definition in the U.S., meat cannot be labeled as “cured” without nitrite addition.
So not so straight-forward 🙂 but I suppose salami on pizza may be something to enjoy infrequently. But back to my original issue, “processed foods” then is to be understood as “tertiary processed foods” with unnaturally extended shelf-life for convenience purposes.