Milk Processing Packaging & Recycling

The following section contains information to educate children about what happens to the milk once it leaves the farm gate, including milk processing, packaging, and recycling.


Tankers transport the milk from dairy farms to a milk processing plant. On arrival, milk from the tanker is tested in a laboratory to ensure that it has been kept at or below 4 degrees Celsius and meets all the standards required to ensure that the factory produces a healthy and safe product. The milk is then pumped into large vats at the factory.

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

The first process is pasteurisation. This is the name given to the process whereby milk is partially sterilised resulting in extended shelf life. Milk is heated to 72°C for no less than 15 seconds and cooled immediately, destroying any harmful bacteria and micro-organisms.

In the days of milk bottles and aluminium tops, cream would separate and rise to the top of the bottle. More recently, the process of homogenisation passes the milk under pressure through very fine nozzles, evenly dispersing the fat globules to create a smooth, creamy texture and taste.

The milk is now all set to be transformed into a wide range of dairy products, including cream, yogurt, cheese, ice cream, butter, or other types of milk such as skim, powdered, condensed, evaporated or flavoured milk. Find out more information at Dairy Products.

milk processing machine in factory


At the factory, milk is sent through a processing line to be packaged in cartons or bottles.

Cartons are made from cardboard lined with a polyethylene plastic, while plastic bottles are made from high-density polyethylene (HDPE). 

The cartons are stored flat until just before they’re filled. They’re then formed into their proper shape, filled with milk, heat sealed, stamped with the use-by date, packed into milk crates and stored in a cool room until they’re collected from the factory and sent to shops and supermarkets.

milk bottles going around a conveyor belt

In the past, milk was always packaged in glass milk bottles. There are some dairies in Australia today who continue to sell milk in glass bottles. 

Milk cartons appeared in Australia in 1958, when the Model Dairy in Melbourne began packaging milk in 150 ml and 500 ml Tetra Pak tetrahedron-shaped cartons. At the time, 160,000 new glass bottles were needed in Melbourne alone every week to keep up the delivery of 1.3 million bottles of milk a day.


  • In 1968 in Victoria, only about 1% of milk was sold in cartons, but by 1972 milk cartons had 20% of the market. 
  • In 1970, the blow-moulded disposable plastic milk bottle was introduced.
  • In 1987, only about 2% of milk was still being sold in glass bottles.


Ever wondered what happens to your milk and yogurt containers after you wheel your recycling bin out onto the kerb? Chances are, they’re back in your house in another familiar shape!

The Australian dairy industry is committed to sustainable practices – both on and off the farm.

Recycling your milk and yogurt containers has enormous benefits for the environment. Not only are materials diverted from landfill when we recycle, but we also save natural resources and reduce our environmental impact.

Whether your milk container comes in plastic or a cardboard, its life isn’t over once you’ve drained the last drop! The empty container is a resource that can be turned into new products.


Plastic milk bottles and many yogurt tubs are made from HDPE. After your recycling bin is picked up by the local council it’s taken to a materials recovery facility, where the containers are separated from other types of plastic. The plastic is then sent to a reprocessing plant and chopped into small flakes, washed with recycled water to remove residual milk, labels and caps, melted and filtered to remove any other contamination. The molten plastic is then turned into pellets that can be remoulded into new products like outdoor furniture, planking, signs, benches, bollards and bins.

These products are coloured right through so they don’t need to be painted, are graffiti-proof, won’t split, rot or be eaten by termites and can last five times longer than the timber alternative, even in harsh coastal weather conditions. For this reason, they’re often known as ‘ever-wood’, a durable, long-lasting substitute for wood.

Recycled HDPE plastic can’t be used to make food packaging because its low melting point means bacterial contamination is possible. But chances are you have an old milk bottle somewhere else in your house; the recycled pellets can also be mixed with new pellets and made into containers for non-food products like detergent and shampoo.

Yogurt tubs are sometimes made from polypropylene (PP) or rigid polystyrene (PS), which can also be processed into pellets for recycling. Look for a Plastic Identification Code (the universal recycling symbol with a number in it) on the container to see what type of plastic it is. HDPE is 2, PP is 5 and PS is 6.

recycling logo  


The milk carton you emptied over your cereal this morning could be sitting on your desk at work shortly!

Milk and custard cartons are made from liquid paperboard (LPB). A one-litre LPB carton is made from the equivalent of five sheets of office-quality A4 paper.

LPB gets its strong card-like feel from a mixture of hardwood and long softwood fibres, making it great for recycling. It’s also bleached in the initial production process, so it doesn’t need extra bleaching when it’s recycled.

After it’s collected from your recycling bin and separated at a materials recovery facility, the carton heads to the paper recycler, where it’s shredded and washed to remove residual milk products.

The carton’s waterproof plastic/polyethylene coating is separated from the paper and strained off for reuse by a plastics recycler. The shredded carton then gets reprocessed into a pulp, formed into sheets of paper, pressed and dried.

The result? It could be the sheet of high-quality office paper on your desk now!


Recycling your milk and yogurt containers has enormous benefits for the environment. Not only are materials diverted from landfill when we recycle, but we also save natural resources and reduce our environmental impact.

  • A product made from recycled materials uses far less energy than one made from new raw materials such as coal, iron ore, oil and trees.
  • For every 41 plastic bottles you recycle, you save enough energy to run your fridge for an hour.
  • A two-seater bench made from 100% recycled plastic contains the equivalent of 680 two-litre milk bottles and saves six cubic metres of landfill.
  • Every tonne of LPB recycled saves 2.5 barrels of oil, 4100 kilowatts of electricity, 31,780 litres of water, four cubic metres of landfill and 13 trees.


When we purchase products that are packaged in materials we can recycle, it is important to make sure that we follow through and recycle them. 

For schools this means setting up a collection system for milk cartons, bottles, and yogurt tubs. If they contain residual milk or yogurt, they could become very messy and smelly, so here are some useful tips:

  • Use an open bin or tub for collection so that you can see what is going in and check that it is not contaminated by food scraps.
  • Put a bucket with water and tongs at the collection point so that students can rinse the container before placing it in the bin.
  • Empty the bin or tub every day, or every second day, so that mice, ants and other insects do not become a problem.