Professor Irven highlights the lack of conclusive evidence supporting the view that partial or total substitution of nitrogen with argon has commercially beneficial effects in terms of shelf life extension and quality for modified atmosphere packaging systems.

‘There have been several theories as to why argon seems to have beneficial effects over nitrogen but none of them completely fit the pattern of what is observed,’ he comments.

The respiration rates of various well known and commonly MAPed fruit and vegetables were measured after being packaged with nitrogen or argon in the gas mixture to compare the effects of the two gases. Although the results showed a decrease in respiration rates with argon, this decrease was marginal.

Air Products, therefore, decided to undertake a set of comparative experiments in collaboration with The University of Lincolnshire and Humberside, using both argon and nitrogen on two commonly available enzymes, one involved in the respiration process (Malic Dehydrogenase) and one involved in the oxidative browning of fruit (Tyrosinase).

The results confirmed that there was only a slight reduction in activity using argon compared with nitrogen.

Additional independent research undertaken by the CCFRA into the effect of argon on fresh prepared produce also demonstrates that ‘Argon-containing MAP treatments had negligible or variable effects on generated in-pack MAP and sensory quality gradings of fresh prepared produce in comparison with equivalent N2-containing MAP treatments.”

“We see that, like nitrogen, argon demonstrates some important properties which are beneficial to the MAP process. What has not been highlighted in the recent debate is that the argument for replacing nitrogen with argon is marginal, especially when bearing in mind the additional gas and piping costs involved,” says Professor Irven.

“It is clear from both a scientific and commercial perspective that the reality of argon versus nitrogen has, until now, not been represented in a balanced way.”