What is aged cheese?
There are two categories of cheese, aged and fresh. As the word implies, fresh cheese can be consumed immediately. Examples of fresh cheese would be cottage cheese, quark, cream cheese, chevre frais, and ricotta.
As far as aged cheese goes, there are a variety of options on how to age a cheese and for how long. Typically, the harder a cheese is, the longer it can be aged. This has to do with the moisture level. The more moisture in a cheese, the faster it ripens and the sooner it needs to be consumed. The reason why it ages faster with a high moisture level is because of the bacteria and enzymes. They play a significant role in the aging process of cheese and work much faster when plenty of moisture is available. Science uses the term “water activity” to describe this.
What happens during the aging of cheese?
Active bacteria and enzymes play the biggest role in the aging process. Aging means the breakdown of fat, protein, and carbohydrates. A cheese is considered aged, cured, or ripened when it is placed in a temperature and humidity controlled environment from 2 weeks to 48 months. Typical aging temperatures are from 10 C/ 50 F to 15 C/ 59 F. Relative humidity should be 90% for a surface ripened cheese. For plastic and wax aged cheeses, the humidity is not significant.
During the cheese making process the cheese maker adds specific bacteria that will eventually create the flavour and taste of each cheese type. In the first stage, bacteria will convert lactose (a form of sugar) to lactic acid. The cheese becomes acidic in the first 24 hours. We distinguish two types of bacteria in cheese making: sphere type and rod type. The sphere types are very active in the first 48 hours and are the main force to acidify the cheese. The rod types are the ones that become active when the actual aging starts, anywhere from 48 hours to 48 months after production.
There are specific enzymes that break down protein, fat, and carbs. Some of these enzymes are found naturally in the milk, especially raw milk, and end up in the cheese. Pasteurization will destroy some enzymes, but the active bacteria in the cheese making process will produce the needed enzymes that were lost. This is why raw milk cheese has a more diverse flavour profile than a cheese made from pasteurized milk.
So how do enzymes affect protein, fat, and carbs?
What happens to the proteins during aging?
The protein break-down is the most important process in the aging of cheese. It causes the cheese texture to become smoother, less rubbery, and meltable.
The protein gets broken down into peptides, then further into amino acids, similar to what happens in our digestive tract. Peptides can create a very palatable and pleasant flavour, whereas amino acids will create a very strong tasting cheese.
Aged cheese is generally much easier to digest than fresh cheese because of the proteins already being broken down. This also explains why aged cheese has a stronger scent, and in the case of over-aging, cheese can smell like rotten eggs. This is ammonia, the last stage in the protein break-down.
Some amino acids are freed during the break-down, which produces CO2. Along with some CO2 producing bacteria, this creates the holes in certain cheeses.
What happens to fat during the aging?
Don’t we love the flavour of fresh cream or butter? This is from the large variety of fatty acids in fresh milk fat, combined with a very low level of free fatty acids. During the aging process, the fat gets broken down into free fatty acids and glycerol, which significantly adds to the flavour development. Some cheeses use an enzyme called lipase, which purposely creates a slightly distinct rancid taste, like feta or parmesan. Fat contributes to a smooth and creamy texture in cheese and it also makes the cheese meltable.
What happens to the carbs during aging?
The only source of carbs in cheese is lactose and a minimal amount of carbs produced by the cheese bacteria. Lactose gets converted into lactic acid by the cheese bacteria. This is basically the only contribution of carbs to the flavour in cheese. In most cheeses, especially aged ones, the amount of carbs is minimal.
The 4 different ways to age cheese
1. Vacuum Plastic Wrap
Within 48 hours of the cheese production, the bacteria in the cheese has used up all of the oxygen, and the environment becomes anaerobic. Vacuum packing cheese does not inhibit the ripening process. It eliminates any flavour development than could come from an open surface. The advantage of vacuum packing is that it has a low labour input and eliminates the handling of the cheese. It also doesn’t require a humidity controlled environment. Vacuum packed cheese will not develop any mould and there is no waste due to rind.
Some cheeses, like gouda or edam, are covered with a food grade wax. The wax is odourless and makes an airtight seal; therefore, it has the same effect as a plastic vacuum pack. If there are concerns about plastic residue, wax is a more natural approach.
3. Rind Ripening: What is Rind on Cheese?
Traditionally, all aged cheese created a rind. In the early days of cheese making, there was no way to store cheese airtight. Without a rind, the cheese would start to mould in a very short time. Rind ripened cheese must be kept in an environment with at least 90% relative humidity. This prevents the cheese from drying out and helps the microorganisms to develop the rind.
The main force in this process is a bacterium called Brevibacterium Linens. This bacterium is also found on our skin and is the main reason for foot odour (Eww). I know this might sound grose, but B. Linens contribute largely to the flavour development in a rind aged cheese.
The bacterium is added to water and the fresh cheese is brushed with this water daily. This is also called “smearing” or “washing” the cheese. At first the cheese will develop a slimy surface which will start to dry up during the first month. Once the rind starts to develop, the cheese maker brushes the cheese every second day. Often, cheese caves or aging facilities are contaminated with B. Linens and adding it to the water is no longer necessary.
Can you eat the rind of cheese? Absolutely you can, however, I recommend washing it first like you would wash a vegetable. Personally, I only eat the rind when I melt it. Melted rind, like in a raclette or ham and cheese sandwich, is crispy and tastes really good. Cheese rind also makes good dog treats.
4. Mold Ripened Cheese
There are 3 types of mould ripened cheeses:
- Surface, white molds
- Veined, blue molds
- Blue cheese with a washed rind
- Washed rind cheese with a white mold
- Blue cheese with a white surface mold
Molds that are used for the ripening of cheese are all edible.
Examples of white surface mold ripened cheese would be Brie or Camembert.
Examples of blue, veined molds inside the cheese would be Danish Blue or Gorgonzola.
An example of a washed rind blue cheese is Stilton.
An example of a washed rind cheese with white mould is the swiss ‘Hohle Gasse” cheese.
An example of a blue cheese with white surface mold is the german Cambozola, the name is a combination of the Gorgonzola and the Camembert.
The mold spores are either added directly to the milk, or later sprayed onto the cheese. Blue cheese is stabbed with a number of needles to provide room for the mold to grow inside the cheese. The distinct flavour of mold ripened cheese is a combination of the mold flavour itself and the strong proteolytic activity of the molds, which means that they can break down the proteins rapidly.
How to distinguish an edible mold from bad mold
The difference between an edible mold and a bad mold is that the bad molds produce toxins that can be really unhealthy for the consumer. One of them is aflatoxin, which is known to be carcinogenic.
When you see green or black mold on the surface of a cheese, you can take this as a rule:
- If the mold appears on an extra hard cheese like parmesan: scrape it off with a knife, the cheese is hard enough to prevent the mold threads from growing into it.
- If the mold appears on the surface of a hard cheese like cheddar, cut a ½ inch off the cheese.
- If the mold appears on the surface of a semi hard cheese like havarti, cut off 1 inch of the cheese below the mould.
- If the mold appears on a soft or fresh cheese, then throw the cheese out. There is a good chance that the mold threads have grown all the way through the cheese.
It is easy to distinguish edible molds and bad molds. All white moulds on cheese are good moulds. It’s possible that any cheese surface can develop a bit of white mould. Just scrape it off, or eat the cheese with it. Black and green molds must be properly removed or thrown out.
The aging of cheese is a complex process. This article just scraped the surface.The sky’s the limit when it comes to aging cheese. There are all kinds of local variations on how to add unique flavours to cheese.
Please let me know if the info here was helpful and interesting. If you have further questions, please post them below, I will be happy to answer more in depth the questions you may have.