Scientists are looking at using natural ingredients, such as mango pits, to replace chemicals in preserved foods. (Wilfredo Lee/Associated Press)

When Jodie McKague and husband Adam Larson buy groceries, they tend to shop along the perimeter of the store where fresh produce and meats are sold.

As new parents of a two-year-old, they are making "a more conscious effort about foodstuff," trying to buy "as fresh as possible."

"I don't want my daughter to think the only taste out there comes out of packages," McKague says. "That will make me really sad."

For the McKagues, "preservative" is a bad word.

But scientists at the University of Alberta are working to create food additives that will appeal to people who avoid synthetic materials in their foods by focusing on the power of natural preservatives. Mangos, wheat and barley are all being studied in the hopes of making food safer while at the same time not turning off those opposed to having artificial compounds in what they eat.

"Food processing and distribution are facing new safety issues," says Michael Gaenzle, a professor in the department of Agricultural, Food and Nutritional Science at the University of Alberta.

"It's very difficult to get ready-to-eat produce free of pathogens without damaging the product," he says. "That's a new challenge to keep the food supply safe."

The researchers are trying to come up with preservatives that could be used in ready-to-eat salads, fruits, sprouts and luncheon meats — all of which are prone to the development of Listeria, salmonella, E. coli and other harmful bacteria.

The potentially deadly micro-organisms can survive even when food is in the refrigerator and can spread to hands, counters, utensils and slicers. Listeriosis killed 22 Canadians in an outbreak linked to deli meat in 2008. The Independent Listeriosis Investigative Review, released in July, reported that the number of listeriosis cases in Canada has double since 2005.

The University of Alberta researchers are studying food germ killers that are naturally derived.

"If you replace chemicals with a natural preservative, without compromising safety, the [food] quality is better," Gaenzle said.

Researchers have found bacteriocins — small proteins produced by lactic acid bacteria — can be used to kill the listeria bacteria in meat products.

"Most of these organisms do not harm humans or animals and are used to ferment food — for example, cheese, salami and yogurt," Gaenzle says.

Mango pits effective at killing listeria

Gaenzle has also detected anti-listeria compounds in polyphenols — a chemical present in all plants — derived from wheat and barley.

Fatty acids, also found in wheat and barley, could be used to extend the shelf life of cereals and breads, says Gaenzle. An extract from mango has been found to be "highly effective" at killing listeria on salads and sprouts.

Christina Engels, a PhD student in the department, says mango pits contain tannins — a substance in many fruits, such as grapes.

"These tannins are really a strong natural preservative," Engels says.

Mango is one of the most popular fruits marketed worldwide, she says, but the pits are not used. The preservative could be used as an ingredient in ready-to-eat salads and fresh juices if approved by Health Canada. But getting that approval is not easy.

"All chemicals that are added to a food, whether they are synthesized or derived from a plant extract, have to undergo a rigorous pre-market safety assessment," says Health Canada spokesman Stephane Shank.

There are at least 380 food additives approved for various uses in Canada.

Engels says she chose mangoes for her study because "natural preservatives have a potential market among consumers looking at more organic and natural foods."

However, to be considered organic, a food preservative extracted from a fruit or an agricultural source would have to also come from a product that has been grown organically, says Matthew Holmes, a director with the Organic Trade Association.

As for McKague, the best recipe for her family right now is to avoid preservatives altogether. "If something has been preserved, you don't know what is inside," she said.