From fresh milk to the finished wheel: this is how Swiss cheese is made

There are over 700 varieties of Swiss cheese, but they all have one thing in common: their production starts with Swiss milk. The vast majority of the cheese is made using cow’s milk. Farmers tend to supply their creamery with fresh, low-germ milk from healthy animals twice each day. This single raw material is then used to produce a huge variety of different cheeses. There are so many different factors – including animal breed, feed, climate, milk fat content, different bacteria cultures, type of maturation and treatment – that lend each and every wheel of cheese its individual character.

First, the milk is tested for its bacteriological and sensory condition. The following criteria are considered:

• The number of cells provides information about the udder health of the animals.
• The microbial count provides information about the hygiene of the milking and the milk.
• Inhibitors show whether the dairy cattle have been treated with antibiotics.
• The freezing point indicates the possibility of the milk having been diluted.

The creameries safeguard the production of unpasteurised milk through further tests specific to each creamery. Unless the milk is being used to produce genuine unpasteurised cheese, the milk is gently heated to produce thermised (warmed to 145,4°F) or pasteurised milk (warmed to at least 161,6°F).

The milk in the “cheese vat” is now gently heated up to 86°-89,6°F. The cheesemaker will then add special lactic acid bacteria cultures and the rennet. Adding the cultures increases the acidity in the milk, which increases the effect of the rennet. The milk is then left to stand for 35-40 minutes. Within this time, the rennet curdles the milk – the so-called curdling process. The cheese vat now contains curd: a smooth, pudding-like solid that awaits further processing.

In order to produce the famous AOP cheeses from Switzerland, bacteria are used that were naturally present in milk some 40 year ago and have since been cultivated by Agroscope Liebefeld-Posieux and can be sourced by the creameries from there as microbial strains.

Rennet can be sourced from the stomach lining of young calves (as well as young goats or lamb stomachs), from special bacteria cultures (microbial) or – rarely – from plants (for example, cardoon thistle or solanum dobium) and is used in liquid, powder or paste form. Genetically modified rennet is not used in Switzerland.

Just a few grams of rennet are all that is required to curdle around 220 gal of milk. But rennet does not just curdle the milk; it also helps the cheese to mature before it is eaten.

As soon as the curd has reached the required consistency, it is cut with a cheese harp. A cheese harp may feature wires and/or blades, so that it can cut through the curd. The longer the cheese is stirred with the harp, the smaller the diameter of the small pieces of curd and the harder the final cheese will be. This is because the finer the curd, the less water there is in the cheese. This process varies for different types of cheese – as such, the cheesemaker must work with great precision here.

The curds are now stirred and gradually heated. The higher the desired water content for the cheese, the more it is heated (hard and extra-hard cheese is heated to approx. 51-58 °C, soft cheese to approx. 35 °C). Stirring and warming the curds causes the curd granules to contract and separate from the whey. The cheese solidifies.

Whey is actually a waste product from the cheesemaking process – it is the name given to the green liquid, which escapes from the curd as it is processed. The whey is pumped away and generally spun and then processed into other products. Whey products include whey drinks, whey butter and quark. It is also used in processed foods or cosmetics as whey powder. However, the majority of the whey is used as animal feed.

Note: “Molke”, “Schotte” and “Sirte” are all names used for whey in Switzerland – “Molke” is the most common term in the German-speaking world.

As soon as the cheese has the right level of solidity, it is filled into perforated moulds together with the whey. The whey now drains off and the cheese mass remains in the mould. Cheese brands are applied straight away as a “cheese passport” for identification purposes. The lid of the mould is placed over the cheese and the cheese is compressed. This lends the cheese the desired shape and also helps to remove additional whey.

Depending on the size of the cheese, it can be placed in a bath of brine for between a few hours and two days. The brine bath has a salt content of around 22% and a temperature of approx. 59°F. The high salt content helps to remove more of the whey and the cheese also absorbs the salt. During this process, the cheese solidifies and a rind forms on the surface. This gives the cheese the protection it requires from external influences and helps to keep the shape of the cheese. The brine bath also prevents the formation of undesired bacteria on the surface. The absorption of the salt improves the taste of the cheese. 

Interesting fact: the density of the brine of 2.5 lb / l means that the heavy wheels of cheese actually float in the brine bath. 

The process continues in the cellar. Cheese maturation covers the entirety of the enzyme processes that take place in cheese. A rather tasteless, fresh protein is transformed into a soft, delicious cheese, bursting with character.

Cheese maturation leads to visual, chemical and microbiological changes in the cheese:

• the visual signs include the formation of an external rind, holes inside the cheese ((infobox)), a smooth cheese and changes in colour.
• Bio-chemical processes break down the protein into amino acids and lead to a change in the state of the cheese, making it easier to digest.
• Both microbiological influences and varying production methods can affect the formation of holes.

Maturation spans from a few days to several months or even years. During this time, the cheese turns into a solid. The maturation period depends on the variety and the size of the cheese, and is defined in product specifications and market regulations.

Cheese maturation is also known as affinage. An affineur adds the finishing touches to the cheese during maturation and only presents the cheese for sale when it has reached peak maturation. Special expertise is required to calculate this moment. The flavour of a cheese can also be enhanced through additional treatments with cider, white wine, special herbal brine etc. during this stage.

A popular topic and an issue that sparks all kinds of speculation: what are the holes in the cheese all about?

Gas-forming microorganisms create carbon dioxide, or CO2. In solid or viscous cheese, the CO2 cannot escape evenly and slowly out of the cheese. As a result, large, irregular holes are formed or cracks created in the places where there is a heavy concentration of gas.

The CO2 is distributed evenly in soft cheese. This means that a large, even hole can “grow” gradually in places where the curds have not grown together. CO2 creates good holes due to its high water solubility.

Et voilà! The mystery behind the holes in the cheese has been solved!

Before the cheese is sold, it undergoes thorough testing. This ensures that only excellent quality cheese is sold. The formation of holes, the quality of the cheese, the taste and the external appearance (shape and preservation) are all inspected and assessed.