Mold types of Cheese
Vacherin du Haut-Doubs cheese, a French cheese with a white Penicillium mold rind.
There are three main categories of cheese in which the presence of mold is an important feature: soft ripened cheeses, washed rind cheeses and blue cheeses.
Soft-ripened cheeses begin firm and rather chalky in texture, but are aged from the exterior inwards by exposing them to mold. The mold may be a velvety bloom of P. camemberti that forms a flexible white crust and contributes to the smooth, runny, or gooey textures and more intense flavors of these aged cheeses. Brie and Camembert, the most famous of these cheeses, are made by allowing white mold to grow on the outside of a soft cheese for a few days or weeks. Goat's milk cheeses are often treated in a similar manner, sometimes with white molds (Chèvre-Boîte) and sometimes with blue.
Washed-rind cheeses are soft in character and ripen inwards like those with white molds; however, they are treated differently. Washed-rind cheeses are periodically cured in a solution of saltwater brine and/or mold-bearing agents that may include beer, wine, brandy and spices, making their surfaces amenable to a class of bacteria Brevibacterium linens (the reddish-orange "smear bacteria") that impart pungent odors and distinctive flavors, and produce a firm, flavorful rind around the cheese. Washed-rind cheeses can be soft (Limburger), semi-hard, or hard (Appenzeller). The same bacteria can also have some impact on cheeses that are simply ripened in humid conditions, like Camembert. The process requires regular washings, particularly in the early stages of production, making it quite labor-intensive compared to other methods of cheese production.
Some washed-rind cheeses are also smear-ripened with solutions of bacteria or fungi, most commonly Brevibacterium linens, Debaryomyces hansenii, and/or Geotrichum candidum) which usually gives them a stronger flavor as the cheese matures. In some cases, older cheeses are smeared on young cheeses to transfer the microorganisms. Many, but not all, of these cheeses have a distinctive pinkish or orange coloring of the exterior. Unlike with other washed-rind cheeses, the washing is done to ensure uniform growth of desired bacteria or fungi and to prevent the growth of undesired molds. Notable examples of smear-ripened cheeses include Munster and Port Salut.
So-called blue cheese is created by inoculating a cheese with Penicillium roqueforti or Penicillium glaucum. This is done while the cheese is still in the form of loosely pressed curds, and may be further enhanced by piercing a ripening block of cheese with skewers in an atmosphere in which the mold is prevalent. The mold grows within the cheese as it ages. These cheeses have distinct blue veins, which gives them their name and, often, assertive flavors. The molds range from pale green to dark blue, and may be accompanied by white and crusty brown molds. Their texture can be soft or firm. Some of the most renowned cheeses are of this type, each with its own distinctive color, flavor, texture and aroma. They include Roquefort, Gorgonzola and Stilton.