About Dairy Products

The following topics in this chapter contain relevant information on Australian dairy products:

Milk

Milk is an amazing natural food which scientists have not been able to copy exactly. Milk is made of water, protein, carbohydrate, fat, vitamins and minerals. The amount of two of the ingredients - protein and fat - depends on the type of cow, her age and what she eats. When milk from many cows is mixed together, these differences even out and we can assess its composition.

The main types of proteins in cows' milk are called casein and whey proteins and are only found in milk. The carbohydrate component of milk is lactose - a type of sugar that does not taste as sweet as cane sugar.

Dairy foods provide a unique package of over 10 essential nutrients our bodies need to function at their best including: calcium, protein, carbohydrate, vitamin A, vitamin B12, riboflavin, magnesium, potassium, phosphorous and zinc.

At the processing plant, two things need to happen before the milk is packaged and sold.

First, the milk is pasteurised. This is a sterilisation process designed to kill any harmful bacteria. The milk is gently heated to 72 degrees Celsius and held at that temperature for 15 seconds. It is then cooled immediately so that the taste and nutrients are not affected. The process is named after Louis Pasteur, the man who invented it.
The milk is then pushed through tiny holes which mixes the cream evenly into the milk. This process, called homogenisation, makes the milk smooth and creamy.
The milk is now ready to be transformed into a variety of dairy products including yogurt, cheese, cream, ice cream, butter and other types of milk such as skim, reduced or low fat, long life, flavoured, powdered or condensed milk.

A milk factory producing fresh milk can process half a million litres of milk per day. From the time milk is received at the factory, it can be processed and packaged within 12 to 16 hours and then it is transported to retail outlets.

How Fat is Removed From Milk

 

The fat is separated from the milk using a machine called the centrifugal separator. This machine has a bowl with discs which rotates at high speeds and causes the lighter components in milk (the milk fat and cream) to stay towards the centre of the bowl while the heavier component (the skim milk) is thrown towards the outside of the bowl. The cream enriched with milk fat is removed from a separate outlet connected to the centre and is used to make butter and cream products. The skim milk is collected from the outside of the bowl and is generally used to make skim milk powder, yogurt etc. When making skim, reduced fat and low fat milk, the skim milk and cream are mixed in different proportions to provide flexibility in adjusting the fat and protein levels required for each product.

Cheese

Cheese Vat

Cheese contains many of the nutrients found in milk, because it is made from milk. There are over 100 different types of cheese made in Australia and each has a special recipe. The most popular cheese in Australia is cheddar cheese. There are many steps in the process of cheddar cheese making:

 

 

 

 

 

 

 

 

 

  1. Fresh pasteurised milk is pumped into large containers. Special bacteria called starter culture are added to the milk, which helps give cheese its unique flavour and texture.
  2. The milk is then heated to 30 degrees Celsius for 40 minutes, which is the temperature bacteria love to live in and need to grow. During this time an enzyme called rennet is added to the milk which makes the milk set into what looks like milk jelly (curd).
  3. The curd is cut into small pieces, heated and stirred. This makes the curd split into parts - the curds and the whey. At this stage the curds look like chunks of tofu and the whey looks like water. The curds contains all the ingredients needed to make the cheese and so the mixture must be stirred for around 2.5 hours to get rid of as much of the whey as possible.
  4. The curds and whey are pumped into a machine called a cheddaring unit, where the whey is drained away (to be used to make ricotta cheese) and the curds are stacked on top of each other. After a while they stick together creating one big block of cheese. This 'cheddaring' process takes about 45 minutes.
  5. The curd is then cut into chunks about the size of potato chips, salt is mixed in which helps to preserve the cheese and give flavour, then the chips are sucked into a tower where they are pressed into blocks, each weighing about 20 kg. These blocks are put into sealed plastic bags and metal containers, before being placed in a maturing room at 8 degrees Celsius. They are left in the maturing room for between two and 12 months, depending on the level of maturity required. Mild cheddar only needs between one and three months maturing, while vintage cheddar needs from one to two years. The longer cheese is matured the stronger in flavour and more crumbly in texture it becomes.
  6. After it is matured, the cheese is ready to be distributed and sold.

Common Questions About Cheese

Following are some commonly asked questions about cheese:

How are soft cheeses made different from cheddar?

The cheese making process starts off the same, but to make soft cheeses, a different type of starter culture is used and sometimes special safe moulds are added. Soft cheeses might also be matured for different amounts of time.

Is the mould on cheese safe to eat?

There are different types of mould on cheese. Some moulds, such as the fluffy white mould on the outside of brie, or the streaks of blue mould in blue cheese, are perfectly safe to eat, as they are special moulds that have been grown to give the cheese its unique and delicious flavour.

Sometimes unwanted mould grows on cheese, such as cheddar, if it has been left for too long. You will see little spots of blue or green mould appear on the cheese and this is not safe to eat as it is often a wild mould that produces toxins that are poisonous to humans. If it is just a little spot of mould, you can cut a thick slice off all the edges of the cheese and eat the remainder, but if you're not sure, or if it is covered in mould, you should throw it away.

A fun experiment for your students to see how mould grows is to cut blue cheese with a knife and then cut cheddar cheese with the same knife. Put the cheddar back in the fridge for a couple of weeks. They will see how some of the blue mould spores will grow on the cheddar cheese. (Remind your children not to eat the mouldy cheddar when the experiment is over).

Why is cheddar yellow, but cream cheese white?

The longer a cheese is matured, the more yellow, dry and crumbly it becomes in texture. Cream cheese is a very fresh cheese that has not been matured for very long. It is very moist and still quite white in colour. Cheddar cheese can be matured for up to two years or longer. As the cheese dries out, the yellow pigment becomes more and more concentrated. This is why some cheeses are more yellow than others.

Australian cheeses are often more yellow than many of the cheeses from Europe. This is because Australian cows are often fed on fresh pastures which naturally contain beta-carotene - a yellow pigment that is also found in carrots. This means that the milk from those cows is creamier in colour which makes a more yellow cheese.

What is rennet and where does it come from?

Rennet is a special enzyme (protein) that is found in the stomach of cows. The rennet is what causes the milk to coagulate into a curd. Centuries ago, they would use the rennet from a cow's stomach to make cheese, but now we use special rennet made in a factory from vegetable materials so no cows are hurt in the process.

Legend has it that cheese was invented when a nomadic herdsman put his milk in a bag made from the stomach of a young animal, so that he could carry it around. When he went to get the milk out, it had turned to curds and whey!

Yogurt

Yogurt is fermented dairy food made by blending milk and live bacterial cultures. It is a rich source of calcium and contains over 10 essential nutrients including vitamin A, vitamin B12 and riboflavin.

There are six steps in the yogurt process:

  1. Fresh whole milk is separated into cream and skim milk.
  2. The milk is then pasteurised to kill any harmful bacteria.
  3. It is then blended together, to make the yogurt thicker and more concentrated. Extra sugar can be added at this point if desired.
  4. The mix is homogenised, to more evenly distribute the fat in the milk and give the yogurt a creamier and more consistent feel, and then cooked at 97 degrees Celsius for seven minutes.
  5. The mixture is then cooled to 42 degrees Celsius. During cooling, beneficial bacteria are added to the milk mixture. These bacteria live off natural sugars (lactose) in the milk and convert them into lactic acid.

    Lactic acid makes the yogurt set into a soft curd, and gives it its unique tangy taste and texture. The yogurt is left for four to six hours to allow it to mature and for all the milk to be converted into yogurt.
  6. After cooling, any extra flavours and fruit can then be added to the yogurt before it is packaged, stored in a cool area, and then delivered to stores.

Butter

Butter is a 100% natural food. For centuries it has been enjoyed for the added taste, texture and visual appeal it provides to so many foods we love to eat.

Following is how butter is made:

  1. To make butter, fresh milk is first separated into cream and skim milk, cooled and put into a storage tank.
  2. From storage, the cream is pasteurised at 95 degrees Celsius to kill any harmful bacteria.
  3. The cream is aged. This is a process of controlled cooling which takes 12 to 15 hours, and helps to give the fat the right structure.
  4. The cream is then separated into buttermilk and butter using a churning process. This can be done using a machine called a continuous butter maker. This process involves the cream being mixed until the fat hardens into butter grains. At the same time, buttermilk (the remaining fat content) is drained off and put into storage to be used for other products.
  5. Salt is added to the separated butter to help preserve it and enhance the flavour.
  6. After a final mixing process, to remove any excess water and make sure that the salt is spread evenly throughout the butter, the butter is then pressed into huge blocks and cut into different sizes. It is then packaged to be distributed to stores and sold to the public.

Cream

Cream is the fat component of milk and is produced by the following:

  1. Cream is made by the separation of fresh milk. This is done using a special machine (centrifuge) which spins around rapidly. The force created by the spinning throws the skim milk to the outside of the bowl. Because the cream is lighter than the skim milk, it remains in the centre where it can be collected.
  2. Thickeners can then be added to make thickened cream.
  3. As with most other milk products, cream is pasteurised (heated to destroy any harmful or unwanted bacteria) at 75 degrees Celsius.
  4. The cream is cooled to 4 degrees Celsius, and can then be packaged and sold to the public.

 

Ice Cream

Ice cream comes in a variety of different forms and flavours. Approximately 70% of the ingredients come from milk.

The process for creating ice cream is described here:

  1. Ice cream is made from a mixture of milk solids, sugars, stabilisers, emulsifiers and water, which are all blended together.
  2. Once blended, the mixture is pasteurised (heated to 86 degrees Celsius to destroy any harmful bacteria).
  3. Then it is homogenised (to distribute the fat evenly). This ensures that the ice cream is smooth and more resistant to melting.
  4. The mixture is then allowed to cool overnight at 1.4 degrees Celsius in storage tanks. This ageing process gives the ice cream improved body and texture.
  5. Any desired flavours or colours can be added to the mixture before it is pumped into freezers, where it is whipped, aerated, and frozen to be packaged before sale.

Australian Consumption of Dairy Products

For most Australians, milk and other dairy foods have been enjoyed as a staple part of our diet since early childhood. As one of the core food groups, dairy foods play a key role in a balanced diet.

The Australian dairy industry produces a huge variety of dairy products - there is something to suit every lifestyle and occasion.

Per capita consumption of drinking milk is estimated at 104 litres. The most popular milk product is the two-litre plastic bottle of regular milk, which makes up 40% of milk sales.

Australians enjoy a variety of cheese and consume on average of 11.8 kg every year per person. The most popular cheese is cheddar, however speciality cheeses continue to grow in sales every year.

Australian manufacturers produce a range of yogurts with a number of flavour combinations as well as new products such as drinking yogurts. Per capita consumption of yogurt is estimated at 6.9 kg.

Where Australian Dairy Products are Sold

It is difficult to pass any food store and not spot a dairy product for sale. More than 80% of Australians of all ages eat or drink a dairy food in any given day. Milk is the most popular dairy product in Australia, followed by cheese and then yogurt and dairy desserts.

Every year the average Australian drinks 104.1 litres of milk, eats 11.8 kg of cheese, uses 4.1 kg of butter and consumes 6.9 kg of yogurt. Many other products, including muesli bars, chocolate, soups, breads and cakes also have milk as an ingredient.

Every year the world is consuming more dairy products because the global population is growing and more consumers are discovering the benefits of eating dairy products. This means there is an opportunity for Australia to export more dairy products each year.

Australia exports approximately 40% of the dairy products it produces, while 60% are sold within Australia.

Australian dairy foods have a large market overseas - especially in countries where it is either too hot or dry to keep cows, or where the population density is so great that there is little space for dairy farming.

Australia is the third biggest dairy exporter in the world and ships dairy products to more than 100 different countries. The most common products exported are cheese, butter and milk powder.

Australia's biggest export market is Asia. Australian cheese is particularly popular in Japan, where we export between 70,000 and 100,000 tonnes a year. Other major markets include Singapore, Malaysia, Indonesia, China, the Philippines and, in the Middle East, Saudi Arabia.

Now go to Do-It-Yourself Dairy.