Ancient plant oils seen fighting food pathogens

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Agriculture and Agri-Food Canada release

3/19/2009 6:47:00 PM

Oils derived from cinnamon and cloves do more than taste and smell good -- they can also fight food-borne diseases, such as E. coli and salmonella, researchers are discovering.

This natural ability of some ancient natural oils -- from geraniums, cloves, wild oregano, cinnamon and thyme, for example -- offers promise in finding alternatives to antibiotics used in animal feed, according to researchers at Agriculture and Agri-Food Canada (AAFC) who are leading the study in collaboration with the Public Health Agency of Canada and the University of Guelph.

"These essential oils can potentially be one of many new and innovative tools for controlling food-borne bacteria at the source, while at the same time reducing the need for dietary antibiotics," says Dr. Joshua Gong, a research scientist at AAFC's Guelph Food Research Centre.

Bacterial pathogens are a common and ongoing concern in animal health and welfare as well as food safety. For example, E. coli causes diarrhea in newly weaned piglets, delaying growth and affecting subsequent performance and production. Other pathogens, such as salmonella, can sometimes be found in meat products and has the potential to be transferred to humans.

However, consumers have expressed concerns that the use of dietary antibiotics in food animal production may contribute to wide-spread antibiotic resistance. These possible effects on human health have increased the demand to develop alternatives.

Plants contain essential oils that defend them from insects, fungi, bacteria and other destructive invaders. Since ancient times, some of these oils have been recognized as safe in flavourings, preservatives and over-the-counter medicines. They have also been used in the manufacture of perfumes throughout history.

The first focus of AAFC's research has been testing these oils as alternatives to dietary antibiotics in swine production. The results showed that many of the essential oils killed the "bad" bacteria without destroying the "good" bacteria in the intestinal tract.

The pig infection experiments show promise. But creating the perfect blend and concentration of essential oils and delivering it to the right section of a pig's digestive tract continues to be a challenge. When mixed with animal feed in a number of cases, the feed completely absorbed the antimicrobial compound and the oil had no effect.

With funding from Ontario Pork ($30,000, matched by AAFC through its Matching Investment Initiative) the research team has identified a technique to encapsulate the essential oil, thus protecting the oils from interacting with the pig feed and delivering them to the target area.

"Through encapsulation, the oils were rapidly released in the small intestine, which is known to be the ideal site for maximum effect in controlling the growth of bad bacteria and disease-causing pathogens in swine," AAFC research scientist Dr. Qi Wang said. "However, each oil has unique properties and may require a different carrier to help it retain its anti-microbial activity in transit down the digestive tract."

Before additional animal tests are performed, the team plans to look at antimicrobial activity of the selected essential oils when mixed in various forms (dry powder, liquid suspension) with pig feed and then subject these trials to simulated digestion.

"Our team is excited about the possibilities for applying this research," Wang said. "It's amazing when you think that something as simple as essential oils may help animals and humans maintain digestive health. At the same time, these essential oils may be an alternative to synthetic antibiotics to manage food-borne pathogens."



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