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Dairy Council

How is it made?
Cheese, butter & yogurt


Milk has been made into cheese here for thousands of years. Traces of milk-fat residue discovered by archaeologists inside earthenware pottery show that we’ve been making cheese since Neolithic times in the 4th millennium BC.

Today, approximately 40% of all milk from Northern Ireland farms which is used to make dairy products is made into cheese. 

Although advances in technology have meant that some stages in the process have changed slightly over the years, the basic principles of how cheese is made have remained the same.

To make common cheeses, such as cheddar cheese, milk is firstly pasteurised (heated to a minimum of 71.7°C for at least 15 seconds) to kill any bacteria. The pasteurised milk is then cooled rapidly before being pumped into large cheese vats. Here, specially prepared, harmless bacteria, called ‘starter cultures’ are added. These ‘ripen’ the milk, and give the cheese its flavour.

Next an ingredient called ‘rennet’* is added to the milk which makes the milk separate into thick curds and runny whey. The curd is then cut into tiny particles which help release more whey.

The curds and whey are then heated and stirred to about 39°C (although this will vary based on the type of cheese being made). Most soft cheeses do not need to be stirred for as long, and most fresh cheeses will not be cooked. The stirring continues for another hour and then the whey is drained off leaving the curds (cheese). Next the curd is stacked, cut and turned to release more whey. This is called ‘cheddaring’. A little salt is added and the cheese is cut into small pieces called chips. The chips are packed into a mould and pressed. Most soft cheeses, however, are not pressed.

The cheese is then taken out of the mould, wrapped and stored. The longer a cheese is stored, the stronger its flavour will be. Soft cheeses can be ripened or fresh. Fresh cheeses (such as cottage cheese) are not matured and are ready for consumption as soon as the process has been completed. Ripened cheeses (such as Brie) are left in rooms with controlled temperatures and humidity.

Examples of hard cheese: Cheddar (mature, mild, reduced–fat etc)

Examples of soft cheese: Cottage cheese, cream cheese, and Brie–type cheeses.

In NI, our favourite cheese is the traditional Cheddar but contemporary flavour variations and speciality blue-vein and soft cheese varieties are becoming increasingly popular. Find out about our cheese culture and heritage in Northern Ireland. There’s more on the nutrients in cheese in the dairy nutrition section.


* The majority of rennet used for cheese–making in the UK is from non–animal sources which makes the cheese suitable for vegetarians.


Butter is a natural product which is made by churning cream until it becomes semi–solid. Butter is used as a spread, on foods such as bread and toast, but also as an ingredient when cooking and baking.

To make butter, milk is first heated to 50°C and then piped into a centrifuge - a large machine that spins the milk around, separating the cream from the milk. The cream is then cooled to 5°C and stored in a tank until it is ready for heat treatment (pasteurisation).

To make butter from the cream, the cream is churned in a large vat at a high speed and buttermilk is removed. Buttermilk is the liquid which is left behind after churning cream to make butter. The butter is then forced through perforated plates in order to disperse moisture (remove the remaining buttermilk), and work the butter to the desired consistency. Salt can also be added at this stage. The butter is then shaped into blocks, cut and packaged to be sold to consumers. 


Yogurt is believed to have originated thousands of years ago in Eastern Europe and Asia. However, it only began to increase in popularity in other parts of the world during the twentieth century, when suggestions were made about the health benefits of including yogurt in the diet.

Today, yogurt is consumed all over the world, both on its own, and as an ingredient in other dishes. Consumers can choose from a wide variety of plain, flavoured and fruit yogurts.

To make yogurt, milk is first pasteurised. This heating process makes sure any unwanted bacteria are killed, and it also helps to change the structure of the milk proteins, allowing them to set smoothly. 

After heating, the milk is cooled (to around 45°C), and specially prepared bacteria (a mixture of lactic acid bacteria) called ‘starter’ cultures are added. The milk is kept at this temperature for approximately 4 to 7 hours to allow it to ferment. Fermentation involves the harmless bacteria converting the milk sugar (called lactose) into lactic acid which helps to coagulate and set the milk, producing yogurt. The semi-solid structure of yogurt that is formed is part of its unique dairy matrix.

The characteristics of the yogurt depends on the composition of the milk (whole, low-fat etc), the type of culture used and the temperature and length of the fermentation process.

After fermentaion, other ingredients such as fruit may be added to the yogurt. It is then packed into containers and chilled to be sold.

To find out what nutrients yogurt contains, check out the dairy nutrition section.