Retort cups lower carbon footprint of tuna packaging

However, the industry must improve the energy efficiency of certain associated manufacturing processes for plastic packaging types to reach their full eco-potential, scientists from Bangkok’s Kasetsart University pointed out.

The study -- Comparative Carbon Footprint of Packaging Systems for Tuna Products -- was published in the journal Packaging Technology and Science. It was sponsored by the European Union (EU) to drive the development of low carbon trade between Europe and Thailand.

Evaluating the manufacturing process for the packaging type revealed that metal can production yielded 70 per cent more GHGs than retort cups and 60 per cent more than retort pouches.

Interestingly, a full life cycle analysis (LCA) narrowed the gap and showed that retort pouches have the highest carbon footprint of the three, explained lead researcher Ngamtip Poovarodom.

The overall carbon footprint of processed tuna in retort cups was 10 per cent lower than that of metal cans and 22 per cent less than retort pouches, the latter of which had a carbon footprint of 322g CO2 eq, followed by metal cans on 280g CO2 eq and tuna in retort cups standing at 253g CO2 eq.

Differences of less than 10 per cent “should not be considered significant for global warming scores,” the authors noted.

Scientists analysed single serve packages; 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 tuna meat preparation remained the same.

They found that packaging and associated processes made up 20-40 per cent of the tuna’s total carbon footprint.

Packaging production and disposal and product sterilization stuck out, said the researchers, and 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, but its comparative carbon footprint performance improved because more tins could be processed together compared to the two retort packages. Metal also has superior recyclability.

Energy needed to sterilize the package during the preservation process was significant: the retort pouch needed six times more than metal cans and more than twice that of retort cups.

“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,” the study reads.

Choice of food packaging is also contingent 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.