Research breakthrough reduces food poisoning risk

Date: 22/07/2002

Refrigerated, ready-to-eat meals may soon be safer from deadly food-poisoning bacteria thanks to a breakthrough preserving technique discovered by a UWS researcher.

Ms Svetlana Rodgers from the University's Centre for Advanced Food Research has found that adding protective cultures to cook-chill foods during the manufacturing process inhibits the growth of the bacteria that causes botulism.

"Long shelf-life cook-chill foods are those ready-to-eat meals such as soups, casseroles and curries sold in our supermarket refrigerators," says Ms Rodgers.

"These meals are popular among consumers and the food service and hospitality industries because they are fresher, more nutritious and maintain their flavour compared to dried, canned or frozen foods.

"The problem is, cook-chill meals have a milder level of processing, a low salt content and are free of preservatives - making them at greater risk of developing food-poisoning bacteria such as Clostridium botulinum if not stored at the correct temperature.

"We've been investigating ways to improve the food safety design of these ready-to-eat meals by creating antibotulinal barriers that don't compromise the food's quality and taste.

"The research has shown that one of the simplest, most effective ways of preserving cook-chill meals is by adding lactic acid bacteria - a natural protective culture."

Ms Rodgers, who is in the process of patenting her research discovery, says protective cultures have distinct advantages over chemical and physical preservation methods.

"Freezing and increasing the cooking temperature of the products are the most obvious approaches, however they can reduce the quality of the food and increase manufacturers' production energy costs. Other physical methods such as irradiation require specialised equipment," she says.

"On the other hand, chemical preservatives are relatively cheap and easy to apply, but they are at odds with the fresh image of these meals and can often affect the taste.

"Lactic acid bacteria is a natural culture derived from fermented foods and is used in the production of cheeses and yoghurt. It works by simply out-competing the food-poisoning pathogens so they can't survive.

"Lactic acid bacteria is not easily detected in meals, which gives it great commercial potential because it doesn't compromise the food's taste and quality.

"And the health benefits of protective cultures means that cook-chill meals protected with lactic acid bacteria are good for our immune system too."

Ms Rodgers says the next stage is developing effective delivery systems for the lactic acid bacteria.

"We need to ensure that high levels of the good bacteria are consistent during processing and for the food's shelf-life," she says.

"One solution is to develop 'active' packaging - packaging that can trigger the release of protective cultures into the product and enhance their survival. We are seeking industry partners to help us develop the technology further and make it commercially available for food manufacturers.

"This kind of development is important when you consider that botulism is one of the most dangerous food poisoning illnesses - ingesting even a minute amount of the toxin can be lethal.

"Hopefully the end result will be high-quality, ready-to-eat meals that are also safer for the consumer."

Ms Rodgers carried out her research in collaboration with supervisors Dr Kaila Kailasapathy, Dr Paul Peiris and Dr Rama Arumugaswany from UWS and Dr Julian Cox from UNSW.

She will be presenting her findings at the 35th annual Australian Institute of Food Science and Technology Convention on Wednesday 24 July 2002 at the Sydney Convention Centre, Darling Harbour.

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