Herbie…loves bugs
By Rossella Lorenzi

The common herb basil may soon find itself being used for more than just adding flavour to food - it might be the answer to food preservation too, as Rossella Lorenzi discovers.

Basil is closely associated with traditional Italian foods, especially pasta and tomatoes, but it could also end up as the latest in wrapping for perishable foods.

No one had aver thought to use this delicious and aromatic herb in active packaging, but when incorporated into a polymer food wrapping, its essential oils have been found to be crucial ingredients in the battle against dangerous food bugs such as Escherichia coli 0157 and Listeria.

According to scientists from the Technion Institute of Technology in Haifa, Israel, and the Victoria University in Melbourne, Australia, basil is an ideal packaging choice.

"It has shown anti-microbial properties against eight strands of micro-organisms," says Joseph Miltz, a chemical food engineer and packaging expert at the Haifa Technion, and the group's head researcher. "The additives derived from basil that we are using are from a natural source. They are considered by the consumers to be safer than the artificial additives used in other anti-microbial packages."

Indeed, research has already shown that basil's essential oils and the principal constituents exhibit anti-microbial activity against a wide range of gram-negative and gram-positive bacteria, yeast and mould.

Miltz and colleagues laced the plastics with two chemicals extracted from basil: an ether called methyl chavicol and the alcohol linalool. Both contain chemical groups with the ability to attack and destroy the cell walls of a bacterium or fungus. The food wrapper slowly oozes these extracts onto the surface of the food, killing the micro-organism.

Preliminary tests showed that the wrapping shows that the wrapping keep the bacteria at bay for a week longer than ordinary packaging and the researchers say it could be used for meat, fish, baked goods, fruit and vegetables.

But before the basil wrap is put on the market, some crucial improvements must be made.

"One of the biggest challenges is to find the right plastics composition to make the basil-containing wrap." Miltz said. The problem is that production of plastics wrapping is carried out at high temperatures, which cause evaporation of the basil extract molecules. The wrap is also permeable, which means the volatile chemicals escape into the outside atmosphere.

To retain the anti-microbial chemicals in the film, the researchers are developing a multi-layered plastic with an impermeable outer layer and porous inner walls that will limit the flow of basic molecules to the inside of the package.

Meanwhile, Miltz has already solved the problem that affected the Japanese researchers who tried to incorporate extracts of a potent horseradish, wasabi, into packaging. Known for its anti-microbial activity, wasabi unfortunately flavoured the food.

However, this new product does not taint the food with a basil flavour because the levels of methyl chavicol and linalool used are too low. They are also less soluble in water than wasabi and do not cling to the food as much, says Miltz.

The project was presented at the International Association of Packaging Research Institutes (IAPRI), held in Valencia, Spain, in May.

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