Apple films fight germs

Packaging Professional magazine
17 Jul 2011

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
‘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.