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 relevant packaging have significant environmental impacts.2 However, despite this, few studies have examined the energy footprint and other environmental impacts of these processes.
The 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 in 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 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 heating and cooling processes, enabling very efficient heat transfer and 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 results in 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 procedures have lower daily operational costs (e.g., less energy usage) and allow for using lighter-weight PET bottles. As a result, an aseptic system’s Total Cost of Ownership (TOC) is lower than 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 lightweight PET bottles are used with aseptic techniques, 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 CO2e per bottle for the hot fill process, compared to 61.8 g CO2e 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 and 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 pasteurization. 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) and 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 CO2e per bottle for the hot fill process, compared to 24.4 g CO2e per bottle for aseptic filling – a saving of 5.32%. While this may seem small, when applied to a theoretical production of 250 million bottles per year, this represents a saving of more than 1,500 tonnes of CO2e each year.
Based on our experience with thermal processing systems around the world at HRS, we believe that the GHG impacts of hot filling technology are higher than this. Several techniques are used to cool products 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, which 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.
About HRS Heat Exchangers
Located in Kuala Lumpur, HRS Heat Exchangers is part of the EIL Group (Exchanger Industries Limited), which operates at the forefront of thermal technology. HRS offers innovative heat transfer solutions worldwide across a diverse range of industries. With 40 years’ experience in the food and drink sector, specialising in the design and manufacture of an extensive range of turnkey systems and components, incorporating our corrugated tubular and scraped surface heat exchanger technology, HRS products are compliant with global design and industry standards. HRS has a network of offices throughout the world: Australia, Canada, New Zealand, UK, Spain, USA, Malaysia and India; with manufacturing plants in the UK, India, Spain and Canada.
2 Manfredi, M. & Vignali, G. (2014), Comparative Life Cycle Assessment of hot filling and aseptic packaging systems used for beverages. At https://www.sciencedirect.com/science/article/abs/pii/S0260877414003860
3 Scott, D. L. (2008), UHT Processing and Aseptic Filling of Dairy Foods. At https://core.ac.uk/download/5165017.pdf
4 Garcia, H. L. (2021), Life Cycle Assessment of beverage packaging systems: A case study for Mexico. At https://tinyurl.com/23yqta8h