question: Why is mold in bleu cheese safe but black mold can kill you?
comment: When fromagers make cheese with mold (such as bleu cheese), they are very careful to only introduce the specific, intended type of mold - they don't just let it sit and grow whatever molds happen to be in the area. While black mold produces toxic compounds, the specific kinds of mold used in cheese are non-toxic and are safe for human consumption. Sources: [1]( URL_0 ), [2]( URL_1 ), [3]( URL_2 ).
passages: Certain types of cheeses require inoculation of milk curds with fungal species that impart a unique flavor and texture to the cheese. Examples include the blue color in cheeses such as Stilton or Roquefort, which are made by inoculation with "Penicillium roqueforti". Molds used in cheese production are non-toxic and are thus safe for human consumption; however, mycotoxins (e.g., aflatoxins, roquefortine C, patulin, or others) may accumulate because of growth of other fungi during cheese ripening or storage.
  
  Section::::Human use.:Poisonous fungi.
   Cheesemakers choose starter cultures to give a cheese its specific characteristics. Also, if the cheesemaker intends to make a mould-ripened cheese such as Stilton, Roquefort or Camembert, mould spores (fungal spores) may be added to the milk in the cheese vat or can be added later to the cheese curd.
  
  Section::::Process.:Coagulation.
   Several species of the genus "Penicillium" play a central role in the production of cheese and of various meat products. To be specific, "Penicillium" molds are found in Blue cheese. "Penicillium camemberti" and "Penicillium roqueforti" are the molds on Camembert, Brie, Roquefort, and many other cheeses. "Penicillium nalgiovense" is used in soft mold-ripened cheeses, such as Nalžovy (ellischau) cheese, and to improve the taste of sausages and hams, and to prevent colonization by other molds and bacteria.
   As a fungus, "P. camemberti" can produce toxins, in this case, cyclopiazonic acid. The amount of the mycotoxin produced depends on the strain of "P. camemberti", as well as the temperature at which the culture is grown. Additionally, the toxin is typically more concentrated on the crust of the fungus rather than the inner part. In regards to safety, generally, consumers would only receive lower than a 4-μg dose of cyclopiazonic acid. Still, using weaker strains of the fungus is advised, since the secretion of the toxin appears to be natural and necessary, but unhealthy for cheese consumers.
   Brie cheese, like Camembert and Cirrus, is considered a soft cheese. This particular type of cheese is very rich and creamy, unlike Cheddar. This softness allows for the rapid widespread growth of bacteria if the cheese is not stored correctly. It is recommended that brie cheese be refrigerated immediately after purchase, and stored in the refrigerator until it is consumed completely. The optimal storage temperature for brie is or even lower. The cheese should be kept in a tightly sealed container or plastic wrap to avoid contact with moisture and food-spoilage bacteria which will reduce the shelf life and freshness of the product. The companies that produce this cheese usually recommend that their cheese be consumed before the best-before date and no later than a week after. Although the cheese can still be consumed at this time, the quality of the cheese is believed to be reduced substantially. In the case that blue or green mold appears to be growing on the cheese, it must no longer be consumed and must be discarded immediately so that food-borne illness is prevented. The mold should not be cut off to continue consumption as there is a high risk of the mold's spores being already spread throughout the entire cheese.
   "Penicillium roqueforti" and "Penicillium glaucum" are both molds that require the presence of oxygen to grow. Therefore, initial fermentation of the cheese is done by lactic acid bacteria. The lactic acid bacteria, however, are killed by the low pH and the secondary fermenters, "Penicillium roqueforti", take over and break the lactic acid down, maintaining a pH in the aged cheese above 6.0. As the pH rises again from the loss of lactic acid, the enzymes in the molds responsible for lipolysis and proteolysis are more active and can continue to ferment the cheese because they are optimal at a pH of 6.0.
   During mold remediation in the U.S., the level of contamination dictates the protection level for remediation workers. Contamination levels have been enumerated as I, II, III, and IV:
  
  BULLET::::- "Level I": Small, isolated areas ( or less); remediation may be conducted by trained building staff;
  
  BULLET::::- "Level II": Mid-sized, isolated areas (); may also be remediated by trained, protected building staff;
  
  BULLET::::- "Level III": Large, isolated areas (): Professionals experienced in microbial investigations or mold remediation should be consulted, and personnel should be trained in the handling of hazardous materials and equipped with respiratory protection, gloves and eye protection;
   When making soft cheese that involves "P. camemberti", the mold may be mixed into the ingredients before being placed in the molds, or it may be added to the outside of the cheese after it is removed from the cheese molds. "P. camemberti" is responsible for the soft, buttery texture of Brie and Camembert, but a too high concentration may lead to an undesirable bitter taste.
   In contrast to cheddaring, making cheeses like Camembert requires a more gentle treatment of the curd. It is carefully transferred to cheese hoops and the whey is allowed to drain from the curd by gravity, generally overnight. The cheese curds are then removed from the hoops to be brined by immersion in a saturated salt solution. The salt absorption stops bacteria growing, as with Cheddar. If white mould spores have not been added to the cheese milk the cheesemaker applies them to the cheese either by spraying the cheese with a suspension of mould spores in water or by immersing the cheese in a bath containing spores of, e.g., "Penicillium candida".
   Some cheeses have additional bacteria or molds intentionally introduced before or during aging. In traditional cheesemaking, these microbes might be already present in the aging room; they are simply allowed to settle and grow on the stored cheeses. More often today, prepared cultures are used, giving more consistent results and putting fewer constraints on the environment where the cheese ages. These cheeses include soft ripened cheeses such as Brie and Camembert, blue cheeses such as Roquefort, Stilton, Gorgonzola, and rind-washed cheeses such as Limburger.
  
  Section::::Types.
   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.
   Yeasts are also used to produce kefir products, semi-soft ripened cheeses and fermented soy drinks.
  
  Section::::Function of microbial food cultures in food.:Moulds.
  
  Three main types of cheese rely on moulds for their characteristic properties: blue cheese, soft ripened cheese (such as camembert and brie) and rind-washed cheese (such as époisses and taleggio).
   Slime molds have a high resistance to toxic levels of metals; one author was prompted to write "The levels of Zn in "Fuligo septica" were so high (4,000–20,000 ppm) that it is difficult to understand how a living organism can tolerate them." The resistance to extreme levels of zinc appears to be unique to "F. septica". The mechanism of this metal resistance is now understood: "F. septica" produces a yellow pigment called fuligorubin A, which has been shown to chelate metals and convert them to inactive forms.
  
  Section::::Bioactive compounds.
   Dairy industry - Bacteriophages present in the environment can cause fermentation failures of cheese starter cultures. In order to avoid this, mixed-strain starter cultures and culture rotation regimes can be used.
   Molds may excrete liquids or low-volatility gases, but the concentrations are so low that frequently they cannot be detected even with sensitive analytical sampling techniques. Sometimes these by-products are detectable by odor, in which case they are referred to as "ergonomic odors" meaning the odors are detectable, but do not indicate toxicologically significant exposures.
  
  Section::::Exposure sources and prevention.:Food.
   Even in cultures with long cheese traditions, consumers may perceive some cheeses that are especially pungent-smelling, or mold-bearing varieties such as Limburger or Roquefort, as unpalatable. Such cheeses are an acquired taste because they are processed using molds or microbiological cultures, allowing odor and flavor molecules to resemble those in rotten foods. One author stated: "An aversion to the odor of decay has the obvious biological value of steering us away from possible food poisoning, so it is no wonder that an animal food that gives off whiffs of shoes and soil and the stable takes some getting used to."
   Since 1979, studies of French cheese have led to the identification of correlations between "Hafnia alvei" growth and chemical parameters during cheese manufacturing. Several researchers estimated that the level of "H. alvei" reaches 10 CFU/g at the end of ripening process and showed that its growth curve is closely linked to an increase in pH. Similarly, Mounier "et al." determined a "H. alvei" content of about 10 CFU/g in a model smear cheese (soft cheese).
  
  Extensive study of traditional cheeses that have been consumed for years highlight the presence of "Hafnia alvei" in dairy products for more than thirty years.
   To make blue cheese, the cheese is treated with a mould, usually "Penicillium roqueforti", while it is still in the loosely pressed curd form. As the cheese matures, the mould grows, creating blue veins within it which gives the cheese its characteristic flavour. Examples include stilton, roquefort and gorgonzola.
  
  Soft ripened cheese such as brie and camembert are made by allowing "P. camemberti" to grow on the outside of the cheese, which causes them to age from the outside in. The mould forms a soft white crust, and the interior becomes runny with a strong flavour.
   This mushroom appears to have a high tolerance for otherwise inhospitable growing conditions, as it has been found growing on caustic spoil mounds (the end-product of many mining and manufacturing operations) of a soda factory in Krakow, Poland, as well as on abandoned uranium tailings in Ontario, Canada.
  
  Section::::Similar species.
  
  "Plectania nannfeldtii" is a similar-looking fungus with a black-colored stalked cup, but this species has a longer stipe, up to ; microscopically, it has larger spores (typically 23–28 by 11–14 µm).
   Section::::Physical-chemical properties.:Mold growth.
   According to several publications, "Hafnia alvei" is present as a dominant species during the ripening of raw milk cheese.
  
  "Hafnia alvei" is a psychrotrophic bacterium, it originates in raw milk and continues to grow in cheeses such as Camembert. The multiplication is a key factor in the fermentation process and ripening of cheese.
   Section::::Exposure sources and prevention.:Flooding.:Mitigation.
   Section::::Mold-associated conditions.
   Vegetable rennet might be used in the production of kosher and halal cheeses, but nearly all kosher cheeses are produced with either microbial rennet or FPC. Commercial so-called vegetable rennets usually contain an extract from the mold "Rhizomucor miehei".
  
  Section::::Alternative sources.:Microbial.
  
  Some molds such as "Rhizomucor miehei" are able to produce proteolytic enzymes. These molds are produced in a fermenter and then specially concentrated and purified to avoid contamination with unpleasant byproducts of the mold growth.
   A low pH is preferred by the gray mold to perform well. "Botrytis cinerea" can acidify its environment by secreting organic acids, like oxalic acid. By acidifying its surroundings, cell wall degrading enzymes (CWDEs) are enhanced, plant-protection enzymes are inhibited, stomatal closure is deregulated, and pH signaling is mediated to facilitate its pathogenesis.
  
  Section::::Viticulture.
  