The success of HDPE in milk packaging
SABIC Europe is a leading HDPE supplier (high density polyethylene) for milk packaging for the European dairy market thanks to the excellent performance of our high-density polyethylene grades. Our product portfolio includes grades that are suitable for packaging material for all milk types.
Milk packaging solutions: Message in a bottle
High density polyethylene (HDPE) has been widely used in the packaging of dairy products for many years. On the European continent, the round bottles used for sterilised milk were introduced in the late sixties. Later on, the milk packaging market in the USA changed from milk cartons to HDPE for pasteurised milk. The HDPE bottle used for pasteurised milk was introduced in the UK in the early eighties.
Thanks to its multi-functionality, HDPE is the only packaging material that can be used for all three milk types: pasteurised, UHT, and sterilised:
- The milk market
- Milk packaging concepts
- SABIC's HDPE milk packaging solutions
The European mainstream - or white milk - market consists of around 30 billion litres per year. Total consumption is declining by approx. 0.7% per annum.
Milk can be categorised into fresh and long-life products. The shelf life of milk can be increased by heat treatment. There are three different methods of heat treatment that result in different milk shelf lives.
|Milk type||Heat treatment||Shelf life|
|Pasteurised||72-75°C, 15-40 sec||4-7 days at <8°C|
|UHT||135-150°C, 4-20 sec||6 months at ambient temperature|
|Sterilised||110-120°C, 10-40 minutes||9 months at ambient temperatures|
Pasteurised milk - with a shelf life between 4-7 days - is what people refer to as 'fresh milk'. The development of fresh ESL (Extended Shelf Life) milk began a couple of years ago. With a slightly modified heat treatment, in combination with sterile filling conditions, the shelf life can thus be extended to 14-28 days under chilled conditions.
The type of packaging that can be used depends on the type of milk.
Pasteurised milk has no restrictions in the choice of packaging. Its shelf life is not affected by a barrier layer, because the shelf life is short and the milk is stored chilled.
UHT milk, however, needs a barrier that keeps out light to prevent degradation of the milk. In an HDPE bottle, this can be accomplished by using a three layer co-extrusion structure with a black middle layer to block light transmission.
Sterilised milk, on the other hand, doesn't need a barrier layer to ensure shelf life. The milk is heat-treated after it has been packaged - and therefore the packaging has to resist the heat treatment.
|Overview of packaging concepts that can be used for the different milk types.|
|Packaging||Pasteurised, ESL||UHT||Sterilised (In Bottle)|
|HDPE mono-layer bottle||x|
|HDPE multi-layer bottle:White/black/white coextrusion||n.a.||n.a.|
|Carton PE coated||x||x|
|Carton AL/PE coated||-||x|
For pasteurised and UHT milk, SABICŪ HDPE B6246 is used. The key product characteristics of this homo-polymer are the ease of processing combined with maximum stiffness. The grade has been developed to allow easy and trouble-free processing on a wide range of machines, like reciprocating screw-, wheel- and continuous extrusion shuttle machines. The excellent consistency in quality (low batch-to-batch variation) and the good thermal stability of the resin have contributed to its excellent market position in Europe.
UHT milk requires a 3-layer (white-black-white) bottle to provide a barrier to light. The base material of the different layers is SABICŪ HDPE B6246, coloured with food grade master-batch.
Milk consumption in Europe in 2001 : total 30 million litres
UHT milk was developed in the sixties as a long-life milk with a better taste than sterilised milk. In the early seventies, UHT milk had a market share of around 10%. Thanks to continuous optimisation of taste quality, UHT milk's market share is still growing at the expense of sterilised milk - and today UHT is the largest milk type on the market.
Figure 1 shows the overall market shares of the three different milk types in Europe in 2001.
There is a big difference among the countries of Europe in the type of milk that is consumed. Figure 2 compares the production of pasteurised fresh milk and long-life milk per European country.
Long-life milk includes UHT and sterilised milk, with UHT accounting for 95% of this category. Sterilised milk is primarily used in Belgium, Spain and France, and its share continues to decline.
In Europe, milk packaging is still dominated by cartons. The market share of HDPE bottles was around 18% in 2001 and is growing.
The UK market is by far the largest market for pasteurised milk in Europe and represents half of the European pasteurised milk volume. The HDPE bottle has a strong position in the UK, with a share of 70%. Glass bottles are mainly used in doorstep delivery (still approx. 20% market share in 2001) and predominately in smaller sizes. On the Continent, however, the carton pack is still the preferred packaging solution.
There is a pronounced difference between the packaging solution used for UHT milk and the one used for sterilised milk. The HDPE bottle is the dominant packaging for sterilised milk; in UHT, the carton pack is leading. The volume of HDPE used in sterilised milk is decreasing because of the declining sterilised milk market. In UHT milk, poly-bottles are attacking the strong position of the carton pack, and HDPE is gaining market share. Carton packs are specified for private label milk, whereas the HDPE bottle is used for most branded products.
blow moulding) is the best choice, offering a listed pellet density of 954 kg/m3.
In our laboratories, we are constantly refining the performance of our grades. We realise that, in order to operate in a mature commodity market, the resin quality must be excellent. The machines that produce the bottles for milk packaging and the bottle filling lines are getting faster and faster. Our product quality is designed to run problem-free at very high production efficiency. A combination of easy and stable processing, small batch-to-batch variation, and excellent odour and taste properties are key success factors for our customers.