Friday, July 20, 2012


By far the most critical safety problem being faced by the consumers in many advanced countries is food poisoning caused by pathogenic bacteria like virulent E,coli species, Salmonella and listeria. The products getting contaminated include meat, vegetables, dry fruits, nuts, poultry products etc and fatalities vary in different episodes. In Europe the fenugreek sprout contamination with Listeria claimed several lives before even it is identified and source of supply traced. It is ironical that these deadly infections are more or less confined to rich countries where the safety standards are very stringent and the vigilance infrastructure is most modern. One interesting fact that emerges from a close scrutiny of food safety episodes is that almost all of them involved cold foods which cannot be heat treated because of their vulnerability to significant quality changes not accepted easily by the consumers. Paradoxically one of the most effective technological tools available to "cold sterilize" such foods, gamma radiation is not availed off by the industry due to nonsensical labeling rigidity on the part of the safety authorities. Another alternate option that may soon be available to the processors is the cold plasma technology which is undergoing tests to establish its technical feasibility vis-a-vis food sanitization. The claims being made by the scientific group that is pioneering the development are contained in the report below.  

"May was a rough month for fresh produce. Alfalfa sprouts, bagged salads, and diced onions were recalled because of possible listeria contamination, while baby spinach and papayas were recalled because of possible salmonella contamination. It's enough to make one scout for something new in food safety systems. And Brendan Niemira is working on something. Niemira, lead scientist at the USDA's Food Safety and Intervention Technologies Eastern Regional Research Center in Wyndmoor, Pa., has been studying cold plasma for nearly a decade. The process uses electricity and a gas — such as oxygen — to deactivate contaminating microbes on meats, poultry, fruits, and vegetables. Niemira and his colleague Joe Sites have treated a variety of foods — including almonds, apples, cantaloupe, lettuce and tomatoes — with cold plasma and produced multi-log reductions of E. coli O157:H7, salmonella and listeria. While cold plasma already is used to clean electronics, bond plastics in manufacturing and bind dye to fibers in textile production, its potential remains untapped in the food industry. "Anytime a technology is being developed, it's only going to be used in the industry if it shows some significant advantages," Niemira said. "Cold plasma is a waterless sanitizing process with no chemical inputs, so it's got some attractive points. The big key right now is to develop the technology so that it gives a solid level of sanitizing antimicrobial effects without unwanted side effects. That's the kind of thing that might lead an interested party to petition the FDA." Niemira said that in cold plasma trials with apples and almonds there were no changes in the product's appearance. Another advantage, he said, is the level of efficacy. While most chlorine rinses will give one or two logs of surface sanitization, Niemira said cold plasma systems have been shown to give three or four logs in trials".

As the development has yet to come out of the laboratory of the scientists concerned, it may be quite some time before technological facilities are designed and conditions standardized on a commercial scale. The fact that cold plasma sterilization has already become an industry standard for sanitizing electronic goods and bond plastics and may get accepted, to start with, for sterilization of food machinery surface, conveyor belts etc in the food industry. As multi log reduction in pathogens has been demonstrated using cold plasma, its efficacy or reliability may not be questioned. The present sanitization procedures use high volumes of water, besides chemicals like chlorine even to get a 2 log reduction of pathogens and there fore food industry is likely to accept the new technology as and when it is ready for commercial level operation. Of course investment cost and the recurring expense in using the technology may eventually determine its fate.  


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