Cheese in Europe is made with many old traditions which are still carried on today. The rind develops during the ripening process and protects the cheese from drying out and from unwanted mold. It also gives each cheese its particular taste and smell.
Cheese rind develops when the pressed cheese forms are laid in a salt brine and/or sprinkled with salt. Soft cheeses are only in the brine a half hour or so, while hard cheeses may be brined for up to three days. The salt enters the surface of the cheese and pulls out water, which makes the outer surface of the cheese hard.
After the saltwater bath, cheese is usually ripened in a cheese cellar under conditions specific to each type of cheese. The cheese surface dries out more and becomes even harder. Also during this time, the cheese is treated; it is turned regularly, brushed and washed. Salt brine is rubbed over the surface and sometimes other mixtures containing herbs and spices.
Natural molds and bacteria grow on the surface, too, which helps protect the cheese from decay and gives the cheese even more taste. The hard rind formed through this procedure with no other treatment is edible. One caveat is that pregnant women, the elderly and people with weak immune systems should not eat the rind due to the small chance that Listeria, a harmful bacterium, can also be present.
Not every cheese you buy has completely natural packaging. Sometimes cheese is packaged in plastic before ripening and does not have any rind. Very mild cheeses like Edamer, Butter cheese, and Tilsiter are often packaged this way. Do not eat the plastic packaging, of course.
Parmesan and Printed Rind
The rind of real Parmesan has an imprinted design created with a stamp. It may also have a brand to confirm top quality from the inspector. Imprinting and branding do not change a natural rind. It is still edible if you like it. Printing on rind with food-grade dye is often done to cheeses like Cabot cheddar. This is usually cut off, although the dye is not harmful to humans.
"Schimmelkäse and Schmierkäse"
Some cheeses get their special aromas and tastes from penicillin molds and smear bacteria. Brie, Camembert, and Bavaria blue cheese are made by spreading a mold culture over the cheese and letting it age, which creates a white rind and a fresh, mushroom-like smell. These cheese rinds are usually edible.
Other cheeses are treated with special bacteria during ripening, to create a "smear" on the rind. Red smear (Brevibacterium linens) is used on Münster cheese, Romadur and Limburger. There is also a white smear which is used most famously on "Weißlacker," a cheese made in Bavaria. The rinds of all these washed-rind cheeses are edible.
Hard and semi-hard cheeses such as Emmentaler or Gouda are sometimes coated with paraffin, wax, linseed oil and cloth or plastic after ripening. This protects the cheese for transport to the market. The secondary coating is not edible and should be cut off.
Food Additive E235: While this anti-fungal has no acute toxicity for humans, cheese rind treated with natamycin to prevent unwanted mold growth should not be eaten, but be cut off about a quarter of an inch deep. If the cheese has no rind but has been treated, remove about the same amount from the outer surface. Natamycin-treated cheeses sold in Germany carry a warning against eating the rind. "Biokäse," or bio-cheese in Germany, has no Natamycin.
Centers for Disease Control and Prevention. Listeria (Listeriosis) People at Risk. Updated December 12, 2016.