Retort cups most eco-friendly tuna packaging

15 Sep 2011

Use of retort cups in tuna packaging produces less greenhouse gas (GHG) emissions than metal cans or retort pouches, according to new research from Thailand.

But plastic packaging types will fail to reach their full eco-potential unless industry improves the energy efficiency of some associated manufacturing processes, cautioned the scientists from Bangkok’s Kasetsart University.

Life cycle analysis

Evaluating the manufacturing process for the packaging type only revealed that metal can production created 70 per cent more GHGs than retort cups and 60 per cent more than retort pouches, said the study which was sponsored by the European Union to promote the development of low carbon trade between Europe and Thailand.

But when a full cradle-to-grave life cycle analysis (LCA) was carried out, this gap narrowed considerably – with the surprising result that retort pouches were found to have the highest carbon footprint of the three, said lead researcher Ngamtip Poovarodom.

The overall carbon footprint of processed tuna in retort cups was 10 per cent less than that of metal cans and 22 per cent less than retort pouches.

Retort pouches were said to have a carbon footprint of 322g CO2 eq, followed by metal cans on 280g CO2 eq – with tuna in retort cups logging 253g CO2 eq.

The authors said that any difference of less than 10 per cent “should not be considered significant for global warming scores”.

The study - Comparative Carbon Footprint of Packaging Systems for Tuna Products – was published in the journal Packaging Technology and Science.

Methodology

The research was conducted in line with PAS 2050:2008, and ISO standards 14040 and 14044 on carbon footprinting.

Single serve packages were examined; two-piece cans made of chrome-coated steel and an aluminium pull cap; retort pouches made from PP, aluminium foil and oriented nylon; and retort cups made of PP and ethylene vinyl alcohol (EVOH), with lids made from PET, aluminium, oriented nylon and PP.

The preparation of tuna meat was the same in all cases.

Hotspots

In tuna, packaging and its associated processes accounted for between 20 to 40 per cent of the total carbon footprint.

Hotspots in the LCA assessment were packaging production and disposal as well as product sterilization, said the researchers.

The researchers found that the carbon footprint performance of packaging materials varied at different points in the LCA.

The metal can had the highest footprint in the manufacturing process – because of use of sheet steel, the lacquering coating and the can end construction. However its comparative carbon footprint performance improved because more tins could be processed in a single batch compared to the two retort packages. Its superior recyclability performance was also important.

Energy needed to sterilize the package during the preservation process had a significant effect – with the retortpouch needing six times as much than metal cans and more than twice that of retort cups.

Wake-up call

The study issued a wake-up call to the food packaging and processing sectors, urging it to focus on improving the energy efficiency involved in some parts of plastic packaging production and boosting batch numbers.

“To reduce a product’s carbon footprint, improvements in energy savings or recovery in the production line and an increase in retort capacity per batch should be given priority by the food industry,” it said.

It added that choice of food packaging depends not only on the materials but on the further processing involved.

“These findings show that the low GHG emission embodied in plastics might vanish if the associated processes are not optimized,” said the researchers.

Source: Packaging Technology and Science