With increasing demand for natural packaging products, a group of researchers from the University of Arizona, USA, has created a film from apple purée.

As well as being edible, they claim the film could also offer food safety benefits. Although stringent hygiene measures are in place during food processing, contamination of food still occurs, says Assistant Professor Sadhanka Ravishankar, who led the research team. Ravishankar claims that the apple-based films could provide another layer of protection. ‘Antimicrobial edible films have previously been touted as a solution for potential pathogen intervention,’ she adds.

Novel recipe

To make the films, apple purée was mixed with pectin (a gelling agent), vegetable glycerin and an antimicrobial compound, before being heated, cooled and cast into films. Two different compounds were used to make two different films – carvacrol, the active ingredient in oregano oil and cinnamaldehyde, the main ingredient in cinnamon oil.

Ravishankar’s team then tested the antimicrobial capabilities of the films against disease-causing pathogens on meat surfaces.

The testing method involved dipping chicken pieces into a solution of bacteria (Campylobacter jejuni), wrapping them in the films, and storing them for 72 hours. The chicken pieces were then crushed and plated to assess how much bacteria survived.

‘The results showed that antimicrobial edible films were very effective at reducing the bacterial population on meat surfaces, in some cases it’s 99.9999%,’ says Ravishankar. ‘Cinnaldehyde was more effective at reducing the amount of bacteria on the chicken – we are not exactly sure why. Different bacteria have different sensitivities to the antimicrobials.’

Indeed, the carvacrol and cinnamaldehyde both represent formidable foes to the Campylobacter jejuni bacteria. ‘Carvacrol is reported to disrupt bacterial cell membranes by noncovalent interactions,’ says Ravishankar, while ‘cinnamaldehyde can inhibit certain vital enzymes of the bacteria, resulting in cell death’.

Though the main purpose of the packaging would be to reduce contamination, Ravishankar points out that the consumers could also eat the packaging. ‘Apples have numerous nutritional and bioactive components that may benefit human health.’

However, she notes that, ‘the packaging does not have to be eaten, but making it edible assumes that the compounds within the packaging are safe for human consumption’.

With the technology for making the films already in place, Ravishankar says some additional research needs to be done before we see applebased films in the supermarket.

The team also intends to research other food products and their effects on different bacteria, ‘It looks possible that any food can be wrapped using these films to reduce surface contamination,’ she says.