Liquid nitrogen injection has been used successfully for years in the beverage sector, but has tended to run into problems in a food canning context. This is because, while the gas-phase nitrogen has the advantage of supporting the can wall and allowing thinner gauges to be used, it also puts pressure on the base and end of the can.
For over six years, Ardagh Group's research and development (R&D) centre at Crosmières, France, has been developing the concept – dubbed Nemo – in a drawn, wall-ironed (DWI) two-piece can. It has now worked with Bonduelle on the launch of two bean products for the German market using Nemo, with plans to roll it out internationally across other Bonduelle products.
15% reduction in metal used
Group R&D director Philippe Gimenez explained: "We are using a full-aperture easy-open end, which is stronger and thicker but, at the same time, the metal in the can body is reduced to such an extent that the balance is a 15% cut in the total amount of metal used, compared with a best-in-class benchmark." The reduction in can wall thickness has been an impressive 43%, according to Ardagh, but the overall can is able to withstand pressures up to 4.5bar.
Business development and marketing director for metal Jacqueline Turlings added: "The other difficulty to overcome was to make sure that the filling process with liquid nitrogen injection was robust enough to ensure a fairly stable initial pressure inside the can." This was one of the challenges worked on by the Bonduelle team.
The re-engineered can does away with the need for beading. This has traditionally helped safeguard can integrity, particularly during post-retort cooling, when the pressure imbalance can otherwise cause cans to crumple.
This means, in turn, that the smooth can wall lends itself more to direct printing. "In the cans for the German market, Bonduelle is still using wraparound labels," said Gimenez. "But there is no reason why they could not use direct decoration."
He added: "We will work to try to reduce the end weight, too, from its current level."
While the cost of the tinplate will not be more than for a traditional can, Ardagh said it could not discuss the cost implications of the filling process.
Bonduelle would not comment further on the new can since it claimed it was at the trial stage. But in a statement it referred to "many benefits for the consumer" and called Nemo "a true success story for sustainable metal packaging".
Consumer research has highlighted one less obvious benefit of nitrogen dosing: the appealing hiss as the can is opened.
The French-based brand owner, which operates in many EU markets but not in the UK, is understood to have exclusive use of the can design within its specific product areas.