By Matt Hale, International Sales & Marketing Director, HRS Heat Exchangers
Over the last decade or so, the benefits of aseptic filling technology compared to traditional hot
filling techniques have become well known in the food and drink sector. The benefits in terms of
product quality have been well documented and discussed. 1 However, the environmental benefits,
both in terms of energy consumption and typical life cycle analysis of this packaging method are
less understood.
A number of Life Cycle Analysis (LCA) studies have shown that aseptic filling techniques using ultra
heat treatment (UHT) systems of pasteurisation or sterilisation, which are based on heat exchangers,
generally have lower environmental impacts. 2,3 This is down to two main factors: the packaging used
in the two different processes and the energy footprint of the process itself.
The thermal processing of food and drink products, and the production of the relevant packaging
have significant environmental impacts. 2 However, despite this there have been few studies looking
at the energy footprint and other environmental impacts of these processes.
Aseptic filling provides robust product quality, minimal thermal impact on the beverage, and greater
bottle design flexibility with the ability to use lighter weight PET bottles or cartons. In contrast, hot
filling requires a higher energy requirement, has a thermal impact on the beverage itself, and has less
flexibility of bottle design than aseptic filling.
Key difference between systems
In an aseptic (cold fill) system, the product is pasteurised or sterilised using UHT systems and then
cooled immediately. It is then placed in the packaging which has either been pre-sterilised (or is
sometimes sterilised at filling). Heat exchangers are generally used for both the heating and cooling
processes, enabling very efficient heat transfer and the use of heat regeneration to minimise the
overall energy requirement. In these situations, ‘considerable energy is saved by using the hot
product’s heat to pre-heat the cold one, and vice versa. 2
In a hot filling system, the product is pasteurised or sterilised (using heat exchangers or other thermal
technologies). The packaging is then filled at a high temperature (typically between 80 and 92 °C)
which has the result of sterilising the packaging. The packaging is then tilted or agitated to ensure
complete contact with the hot product and the temperature is maintained for a specified period,
such as two minutes. After this the packing and the product are cooled. How this is done, and how
soon after filling the process is carried out, depend on the product and the packaging. Typical
methods include blast tunnels, falling water coolers or even cold storage.
While the initial capital investment in an aseptic system is often higher than for a comparable hot fill
system, aseptic systems have lower daily operational costs (e.g., less energy usage) and allow for the
use of lighter weight PET bottles. As a result, the Total Cost of Ownership (TOC) of an aseptic system
is lower than for a hot fill system.
Difference in packaging LCA
In practice there are many different types of packaging used in both systems, although in general
terms board-based cartons and light-weight PET bottles are used with aseptic systems, while hot fill
machines are associated with heavier PET bottles, glass or cans.
In an effort to accurately compare the environmental impact of both systems, some researchers
compared aseptic and hot fill systems based on the production of 500 ml PET bottles of orange juice. 2
Because a thicker gauge of plastic bottle is required to withstand the higher temperatures in hot
filling systems, more plastic is used (in this example 24 g for hot filling versus 16 g for aseptic filling).
As a result, the greenhouse gas (GHG) emissions associated with the packaging are 80.4 g CO 2 e per
bottle for the hot fill process, compared to 61.8 g CO 2 e per bottle for aseptic filling – a saving of
23.1%.
Difference in energy consumption
The difference in energy consumption between the two systems is due to different heat treatment,
filling and cooling methods has often been ignored by researchers. One typical (and totally
inaccurate) observation is, ‘the energetic matrix was assumed to be the same for all systems.’ 4 This is
patently untrue, as other studies have shown that ‘There are several advantages to aseptic processing
and packaging over traditional pasteurisation. Advantages include extended shelf life [and] lower
energy costs,’ 3
Where the energy footprint of aseptic filling has been compared to hot filling techniques, 2 it has
shown that, ‘the product treatment in hot filling appears to have higher impacts die to the higher
energy requirement that occurs during the warming and the chilling phases’ and, ‘in hot filling
systems the heat of the treated product cannot be recovered.’
Some of the benefits are less clear cut than may be supposed and vary according to the heating
medium source (such as steam), as well as the electrical and compressed air consumption of different
system components. However, using heat exchangers with energy recovery provides significant
energy savings.
Despite these complications, using the same 500 ml PET bottles of orange juice example above, GHG
emissions associated with energy consumption by the process were 31.6 g CO 2 e per bottle for the hot
fill process, compared to 24.4 g CO 2 e per bottle for aseptic filling – a saving of 5.32%. While this may
seem small, when applied up to a theoretical production of 250 million bottles per year, this
represents a saving of more than 1,500 tonnes of CO 2 e each year.
Based on our experience of thermal processing systems around the world, at HRS we believe that the
GHG impacts of hot filling technology are in fact higher than this. There are a number of different
techniques used to cool product and packaging after hot filling, and not all of these are as energy
efficient as the chilled-water drench described in the above study. For example, where cold rooms
are used, their overall cooling efficiency is low and the electrical energy requirements are significant.
The combined effects
As energy prices around the globe rise rapidly, and the need to take action on climate change
intensifies, more and more food and drink manufacturers are looking to reduce the energy costs of
their production processes. Switching from hot fill to aseptic production lines is increasingly
attractive, and for new lines, the arguments for adopting aseptic techniques are clear.
As the scientific studies above show, overall GHG savings of 24.9 g CO2e per bottle are possible,
something that is far from significant. To discuss how the HRS range of heat exchangers,
pasteurisation and sterilisation technologies, and complete aseptic treatment and filling systems, can
help your business to realise these monetary and environmental savings, please contact us.
