Steel packaging: the sustainable solution

Nutrition is essential for human life and food processing and packaging play a vital role. Steel packaging can help to avoid food waste and packaging waste.

• It can extend shelf life and provide smaller serving units. The steel can is the only packaging for heat-processed food that captures nutrients without preservatives, offering a 100% barrier against water, light and air, meeting the highest food safety standards. It also carries information about its contents.
• After use, approximately 67% of steel cans are recycled. Efforts are on-going to improve this rate, which already exceeds recycling rates for plastics and aluminium, the two most common packaging material alternatives. Every tonne of recycled steel leads to a CO₂ emission reduction of 1.79 tonnes. Steel is 100% recyclable. It is magnetic and, therefore, easy to separate from the waste stream for recycling. Steel is the most recycled material in the world.

Steels are constantly re-invented according to the needs of the time, and packaging steels are no exception. They are constantly made thinner and lighter, yet stronger and easier to shape and weld.

The use of steel packaging can help to reduce greenhouse gas emissions over the entire life cycle of foods. In particular, compared to food preservation by freezing, the choice of steel for packaging is justified by the overall life cycle energy savings.

Demonstrating the advantage of steel

A 2007 US life cycle assessment study¹ by the Network for Business Innovation and Sustainability (NBIS) and their subcontractor² shows that CO₂-equivalent emissions from food preservation by steel canning can be up to 28% less than by freezing in a plastic bag.

In the US, more than half of the green bean crop is canned and a quarter is frozen. A comparison was made between the canning process and a hypothetical relatively clean freezing process³ for a single four-ounce (118 ml) serving of green beans, from arrival at the processing plant until delivery to the wholesale customer. Environmental impacts of food preparation and consumption by the consumer were ignored as they were assumed to be the same for both preservation methods.⁴

As shown in Figure 1, the calculated total global warming impact from canned green beans was 0.212 kg CO₂-equivalents. This is less than the total 0.294 kg for frozen green beans, and points to a better environmental performance for cans on this indicator, as for most other indicators.

Figure 1: CO₂-eq. (kg) in the canned and frozen preservation process for green beans

Although for canned green beans, the majority of greenhouse gas emissions derive from the production of steel, the choice of steel for packaging is justified by overall energy savings. Another study on canned food commissioned by the Steel Recycling Institute⁵ and performed by Scientific Certification Systems (SCS), showed that canning food uses less energy than freezing food.

The results are also consistent with another study carried out in 2005 by the Dutch Organisation for Applied Scientific Research, TNO⁶. This study compared the sustainability performance of several product-packaging systems and concluded that canned carrots are the best performing products in the Dutch market. The unit for this study was 600 grams of carrots, prepared and eaten at home. Seven packaging systems were assessed: fresh (two plastic bag types), frozen (plastic bag and plastic carton) and preserved (steel can, pouch and laminated carton). The products were stored for a variable period before consumption. The actual preparation, including cooking or heating, depends on the nature of the product – fresh, frozen or preserved.

To assess the environmental impact of the food systems, the CML-2 impact assessment method was used⁷. For the canned carrots, transport and packaging are the two lifecycle stages with the most global warming impact. Here, the impact of the food can itself is greatly reduced by the bonus of steel recycling. In total, canned carrots perform considerably better than both the frozen solutions in terms of impact on global warming.

Economical impacts were also taken into account. Costs incurred to get a portion of cooked carrots ready for eating include retail price, transport costs and costs for storage and cooking. Here, only carrots freshly-bunched and frozen in plastic performed better than canned carrots.

However, Dutch market products include imported carrots, in an open market offering fresh produce all year round. As was the case for products grown in the Netherlands only, the environmental impact from canned carrots was lower than for carrots in plastic bag, frozen. Including imported products, canned carrots were the overall eco-efficiency top performers as the need for climate-controlled import of fresh carrots decreased the performance of these carrots.

Food quality, expressed as nutritional content, is important. Due to insignificance of differences in the nutritional value between the product-packaging systems, sustainability is mainly determined by the eco-efficiency. Therefore, for overall sustainability canned carrots were the best performers.

1. In conformance with ISO 14044 standards
2. The Institute for Environmental Research and Education (IERE)
3. Assumptions: Identical processing for both freezing and canning; freezing and frozen storage assumed to be in same location as canning; 1.5% of frozen beans lost in storage, based on estimate of 1-3% lost in storage; blanching performed according to suggested guidelines of the cooperative extension service, and blanching water was re-used eight times; the average bean was frozen for six months; green beans were individually quick frozen (IQF), the industry standard technology.
4. Environmental impacts of the two food systems were calculated using the USEPA TRACI programme, with three of the 11 impact categories directly relating to human health. The Global Warming Impact Indicator measures global warming potential in terms of carbon dioxide units at a hundred year horizon, following guidance of the Intergovernmental Panel on Climate Change (IPCC).
5. From farm to table: An energy consumption assessment of refrigerated, frozen and canned food delivery. Scientific Certification Systems Kirsten Ritchie, B.S., M.S., P.E. Civil Engineering
6. www.tno.nl
7. The CML-2 method is an environmental impact assessment method developed by the Institute of Environmental Sciences (CML) of the Leiden University, the Netherlands