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May 4th, 2013:

‘Plasma’ zaps bacteria in bagged veggies

Experiments showed that bacteria on food surfaces were eliminated with 20 seconds of treatment and 24 hours of exposure to the gases it creates. “Even in the most resistant bacteria-growing media, 45 seconds of treatment gave us complete elimination of the E. coli,” researcher Kevin Keener says. (Credit: Tom Campbell/Purdue University)

PURDUE (US) — Exposing packaged liquids and fresh produce to an electrical field for just minutes might eliminate all traces of food borne pathogens.

Kevin Keener, a professor of food science at Purdue University, looked for new ways to kill harmful bacteria, such as E.coli and Salmonella, that contaminate foods and cause serious illnesses and deaths. His method uses electricity to generate a plasma, or ionized gas, from atmospheric gases inside the food package.

Straight from the Source

Read the original study

DOI: 10.1111/jam.12087

This process creates a wide variety of bacteria-killing molecules including ozone, nitrogen oxides, hydrogen peroxide, and others. These molecules only exist for a few hours and then revert back to the original atmospheric gas, leaving a bacteria-free product.

In findings published in the Journal of Applied Microbiology, Keener and researchers at the Dublin Institute of Technology demonstrated that sealed-package atmospheric plasma works well to kill bacteria in growth media. Their experiments showed that bacteria on these surfaces were eliminated with 20 seconds of treatment and 24 hours of exposure to the gases it creates. Keener says the cost of the process should be comparable to current chemical and heat treatments used to sanitize foods.

“Even in the most resistant bacteria-growing media, 45 seconds of treatment gave us complete elimination of the E. coli,” Keener says. “Under a microscope, we saw holes forming in the cell walls of the bacteria.”

Adapting the technology for liquids could allow development of portable devices to clean drinking water in areas with contamination or that lack other purification methods. It could also allow food processors to bottle juices without first heating them, a process widely used to kill bacteria that can alter products.

“This could be developed to allow you to achieve something similar to pasteurization without the heat and quality changes that occur with that process,” Keener says.

In Europe, especially, new methods are being sought as alternatives to washing foods in chlorine baths.

“Chlorine water works well on hard surfaces. But there can be issues if bacteria get inside organic matter on the produce, making chlorine ineffective,” Keener says.

Keener is working with researchers in Ireland and Spain to develop a pre-commercial system for larger-scale decontamination testing. After that, he would like to build a commercial system that could be used in food-processing plants. Future research will also consider how the process affects food quality.

“Results from recent testing of E. coli bacteria in liquid suspensions demonstrated significant bacterial reductions with no heating or visual color change.” Keener says. “This suggests that atmospheric cold plasma treatment may achieve a cold pasteurization process for liquid foods to extend shelf-life and improve safety.”

The European Community’s Seventh Framework program funded the research.

Source: Purdue University

Tsing Yi toxic waste facility may be moved

Friday, 03 May, 2013, 12:00am

NewsHong Kong


Cheung Chi-fai

Consultant will look into relocating or scaling back chemical waste incinerator that runs at 10pc of capacity

The city’s only incinerator that can handle hazardous waste is chronically underused and may have to be moved from Tsing Yi or scaled down.

The Environmental Protection Department plans to hire a consultant to look into the future of the facility. It will direct the consultant to study the incinerator’s operation, and whether it needs to be downsized or relocated to other locations such as to a rock cavern or reclaimed land.

The consultant will also be asked to forecast the extent of chemical and hazardous waste requiring treatment in the next 15 to 20 years, taking into account import and export controls on such waste and advances in technology, according to a tender document seen by the South China Morning Post.

The plant was commissioned in 1993 and can handle 100,000 tonnes of chemical or toxic waste per year.

However, only 10 per cent of that capacity was used last year, according to figures provided by the department.

About 7,000 tonnes of chemical waste was treated at the incinerator last year. That compares with 50,000 tonnes in 1994, the year after it opened.

It handled 2,700 tonnes of waste oil from vessels last year, versus 47,000 tonnes in 1998.

The department is commissioning the study ahead of the release of its new waste management blueprint, and halfway through the operator’s 10-year contract. Key to the new plan for tackling the city’s waste disposal problems will be determining whether to install infrastructure such as a waste-to-energy incinerator to treat waste that cannot be recycled.

Professor Wong Woon-chung, a waste specialist from Baptist University, said a facility dedicated to treating hazardous waste was essential for the city, but its size and location should be reviewed. “The facility was built 20 years ago when there was not much nearby on Tsing Yi. Now, the island is home to about 200,000 people and there is a need to review whether it is desirable and safe,” he said.

The incinerator occupies a two-hectare site on southeastern Tsing Yi, close to the Kwai Tsing dock from where it collects oily or noxious liquid waste from ocean-going vessels. Under international maritime rules, port authorities are obliged to provide disposal outlets for vessels’ waste.

The area is on the doorstep of an old industrialised district of Tsuen Wan and Kwai Chung, which were once the main sources of chemical waste such as lubricants or spent electrolytic solutions. The plant began handling clinical waste in 2011, in a bid to increase its use. It treated 2,044 tonnes last year.

And it would also provide emergency services in the case of chemical or biological contamination – or a new virus outbreak.

Kwai Tsing district councillor Tam Wai-chun said she had not received any complaints about the incinerator from residents, but would support its relocation. “Who wants something like this in their backyard? It’s just like the urn niches – no one wants them as neighbours either,” she said.

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The plant occupies a two-hectare Tsing Yi site. Photo: Edward Wong


Waste Management

Hazardous Waste


Tsing Yi

Environmental Protection Department