Ozone, one of the main elements in city smog, may provide an effective way to stop fruit and vegetables spoiling without covering them in chemical residues, research suggests.
Exposing fruit to low levels of the toxic form of oxygen for up to eight days prevented almost 95 per cent of fungal infections.
Fungal contamination is the most common cause of spoilage of stored fruit, salads and vegetables.
It is estimated that up to 30 per cent of fresh fruit and veg produce can be lost due to fungal organisms.
Since the 1950s, food companies have used cheap and effective synthetic fungicides to preserve their products. Often these are combined with pre-pack treatments containing chlorine and bromine.
However, this approach raises health issues.
Study leader Ian Singleton, from the University of Newcastle, said: “There are public concerns over pesticide residues on fresh produce. Ozone is a viable alternative to pesticides as it is safe to use and effective against a wide spectrum of micro-organisms. Importantly, it leaves no detectable residues in contrast to traditional methods of preserving fresh produce.”
The findings were presented today at the Society for General Microbiology’s Spring Conference in Harrogate.
Dr Singleton’s team found that low concentrations of gaseous ozone preserved a wide range of stored fresh produce, including strawberries, tomatoes, grapes and plums.
One surprise was that exposing tomatoes to ozone before infecting them with fungus also reduced spoilage.
“This suggests that ozone treatment exerts a ‘memory’ or ‘vaccination’ effect that protects fruit from damage. It is unclear how this phenomenon works, but it is certainly worthy of further, detailed investigation.”
Careful work was needed to optimise levels of ozone and length of exposure, he said.
Dr Singleton added: “Different fruits have been shown to have different tolerances for ozone. We need to look carefully at how we control the atmospheric concentration of the gas in stores and transit containers, since levels of ozone that are too high can damage produce, causing financial losses.”