Moldy Cheese: What Types Harbor This Fungus?

Cheese is 99.99% milk, with most of the liquid drained away. To transform the fats and proteins into flavour, the cheesemaker adds cultures of microscopic moulds, bacteria, and/or yeasts. There are two kinds of mould-ripened cheeses: internally ripened, which grow mould inside the cheese, and externally ripened varieties, which grow mould on their exterior. Blue cheese is an example of an internally ripened cheese, with colourful veins of mould running through it. The cheesemaker adds Penicillium roqueforti mould to the milk and pierces each wheel with a long, thick needle to let in oxygen, allowing the mould to grow throughout the interior. Externally ripened cheeses include Brie, Camembert, Trillium, and Little Lucy Brie, which develop a white bloomy rind.

Blue cheese is an example of a cheese with mould

Blue cheeses are typically aged in temperature-controlled environments. The process of making blue cheese consists of six standard steps, with additional ingredients and processes required to give the cheese its particular properties. In the first phase of production, a Penicillium roqueforti inoculum is prepared. This is then added to the cheese curds, along with Brevibacterium linens, which is responsible for the cheese's aroma. The curds are then knit in moulds to form cheese loaves with a relatively open texture. The moulds are inverted frequently to promote whey drainage, which continues for 10-48 hours. Salt is then added to provide flavour and act as a preservative. The final step is ripening the cheese by ageing it. When the cheese is freshly made, there is little to no blue cheese flavour development. Usually, a fermentation period of 60-90 days is needed before the flavour of the cheese is typical and acceptable for marketing.

During the ripening process, the temperature and humidity in the room are monitored to ensure the cheese does not spoil or lose its optimal flavour and texture. The ripening temperature is generally around eight to ten degrees Celsius with a relative humidity of 85-95%. At the beginning of this process, the cheese loaves are punctured to create small openings to allow air to penetrate and support the growth of the Penicillium roqueforti cultures, thus encouraging the formation of blue veins.

Blue cheese is safe to consume, and the mould on blue cheese is from the same family of spores used to make penicillin. The mould Penicillium roqueforti does not produce toxins by itself and is not dangerous to humans. In fact, it is added to the cheese to greatly accelerate processes that create the unique look, texture, and taste of blue cheese.

Mouldy cheese should be discarded

For soft cheeses like Brie or Port Salut, about a quarter of an inch should be cut away from any surface where mould is visible. Harder, aged cheeses like aged Cheddar or Parmesan can simply be scraped to remove the mould. With white, fuzzy mould, tinged with green, the flavour effect is minimal and the mould can be safely cut away without incident.

Black or grey mould is less desirable, and you should cut away more of the cheese to remove any parts that might be impacted. Any mouldy cheese that smells of ammonia or is both mouldy and wet should be discarded.

If most of the block of cheese is covered in mould, it should be thrown away.

Fresh cheeses are consumed soon after being made and don't usually have mould

Fresh cheeses have a high moisture content compared to other types of cheese due to their minimal transformation from milk and limited aging process. They are typically mild, milky, or slightly salty in flavour, with textures ranging from crumbly to stretchy to spreadable. Examples of fresh cheeses include mozzarella, ricotta, cream cheese, feta, burrata, queso fresco, and halloumi.

The process of making fresh cheese involves ripening the milk by adding starter cultures, which convert the milk sugar (lactose) into lactic acid, encouraging the milk to thicken. For denser and thicker curds, rennet is added. Once the curds form, the liquid (whey) is drained, and the remaining solids are turned into cheese.

While fresh cheeses don't usually have mould, it's important to note that all cheese is made with the help of microorganisms like mould, bacteria, and yeast. These microbes work together to coagulate the milk and create the distinct flavours and textures of different cheeses. However, fresh cheeses are consumed soon after production, leaving little time for mould to develop.

In summary, fresh cheeses are meant to be consumed soon after production and typically don't have mould. They are characterised by their mild flavours, high moisture content, and diverse textures. The quick production process and minimal aging set fresh cheeses apart from other varieties and contribute to their overall freshness.

Mouldy cheese can sometimes be eaten after cutting off the mould

It's true that mouldy cheese can sometimes be eaten after cutting off the mould. However, this depends on the type of cheese and the type of mould.

Firstly, it's important to note that mould is a common part of the cheesemaking process. Many cheeses, such as blue cheese, brie, Camembert, gorgonzola, and Stilton, are made with mould and are safe to eat. In these cases, the mould is usually already present when the cheese is bought and is uniform in colour and texture.

However, when mould appears on a cheese that is not supposed to have it, such as mozzarella, cheddar, or Swiss cheese, it is generally recommended to throw it away. While it may not make you sick, it can negatively impact the flavour and texture of the cheese.

For hard cheeses, such as Parmesan or cheddar, it is usually safe to cut off the mouldy parts and consume the rest of the cheese. It is recommended to cut off at least an inch around and below the mould spot to ensure all the mould is removed.

On the other hand, soft cheeses, like ricotta, cottage cheese, cream cheese, or chèvre, are more susceptible to mould growth. In these cases, it is recommended to throw away the entire container, as the mould may have spread beyond what is visible.

Additionally, it is important to note that black or dark red mould, while rare, can be toxic, so these cheeses should be discarded.

To prevent mould growth, it is recommended to store cheese properly, such as in the crisper drawer of the refrigerator, wrapped in cheese paper or wax paper, or in a vacuum-sealed bag.

Cheesemakers babysit the cheese, ensuring the right type of mould is growing

Cheesemaking is a delicate process that requires careful attention to detail to ensure the desired outcome. When it comes to mould, cheesemakers play a crucial role in babysitting the cheese, allowing the right type of mould to grow in the right place at the right time.

Mould plays an essential role in the cheesemaking process, with most cheeses owing their distinct flavours and textures to the growth of specific mould cultures. Cheesemakers carefully select and add mould cultures, such as Penicillium roqueforti or Penicillium candidum, to the milk during cheesemaking to develop the desired characteristics in the final product.

For blue cheese, mould cultures are added to the milk, and the cheese wheels are pierced to allow oxygen to fuel the growth of mould throughout the interior, resulting in colourful veins running through the cheese. On the other hand, cheeses like Brie, Camembert, and Bloomy Rinds are externally ripened, developing a white bloomy rind from the Penicillium candidum mould. Cheesemakers carefully tend to this mould, patting it down and flipping the cheese over to ensure even growth.

The art of cheesemaking involves a delicate balance between nurturing the desired moulds and intervening when necessary. Cheesemakers regularly check on their cheeses, monitoring for any unwanted mould growth that may compromise the flavour and texture of the final product. They carefully scrape or slice off any unwanted mould, ensuring the cheese remains appealing to customers while maintaining its intended characteristics.

In addition to the desired mould cultures, natural rinds are also home to various yeasts and bacteria that contribute to the unique flavours and aromas of the cheese. These wild microbes develop during the ageing process, creating a diverse community of microorganisms that work together to create the complex flavours found in many cheeses.

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