Monday, July 13, 2009


Food technologists have the onerous job of developing ways and means to protect food from spoilage of any type and save the people from the adverse consequences of consuming spoiled foods. Food infection is as old as human history and man has been striving hard to preempt such incidences of food related damages to the society. The recent food contamination episodes in the most powerful nation on earth, United States of America have compelled its president to overhaul the food safety monitoring system there, on a war footing to preempt such mishaps in future. How far man will succeed in his cherished goal of achieving absolute safety remains to be seen.

Living creatures in nature are endowed with amazing ability to survive adversity and the the fundamental basis of evolution is centered around this phenomenon of adaptation. There are millions of instances when living organisms in different shapes, sizes and complexity of structure and intricacies of the working systems were able to outlive the calamities facing them through sheer ingenuity and marvelous adaptive capabilities endowed on them by Mother Nature. If man has been able to attain a higher degree of survival in the ladder of evolution, it is because of his superior attributes conferred on him during the development process. When it comes to single cell organisms like bacteria, their simple structure masks their ability to survive under most trying circumstances and it is a tribute to their strength that man's superior intelligence has not wiped them out of this planet. The way the recent H1N1 virus was able create a global scare still haunts the world with WHO declaring it as pandemic and despite tremendous advances in the field of virology, no one can predict when the next mutated virus is going to appear on the horizon to cause havoc!

There are many pathogenic bacteria that haunts food industry and the restaurant sector and these include Salmonella, Listeria, virulent E. coli, etc. Food scientists have been able to design excellent technologies to make food safe from these infecting vectors with endo- and exo- toxins. Annihilation of these disease causing organisms in the food, through thermal, chemical, physical, irradiation and biological techniques has been possible with reasonable assurance of safety. Modern machinery designs incorporate CIP(Clean In Place) features that enable food technologists to ensure freedom from contamination between batch operations. Still contamination of processed food continues to pose dangers to the processors as well as the consumers. Of course one can always find the reason in many cases, most of them being management failures but it does not help unless the food safety regime is able to prevent such system failures.

It was almost two decades ago microbiologists raised the alarm after discovering the ability of bacteria to form biofilms which are colonies of these microorganisms, tougher to destroy than planktonic cells. Quorum sensing(QS), known in higher forms of living creatures like insects, was found to be existing in bacteria also which enables them to form biofilms on inter face between liquid and a solid surface. Using signaling molecules called auto inducers or pheromones, the bacterial cells can communicate with each other in the same species or with other species for coordinating through QS and often act as multicellular organism capable of making, detecting and integrating information from multiple auto inducers for cohesive action. While oligopeptides are used as signaling molecules by Gram positive bacteria, homo serine lactone serves the same role for Gram negative bacteria. QS controls such varied activities like bioluminescence, secretion of virulent factors, biofilm formation, sporulation and exchange of DNA.

Biofilm formation occurs on solid surfaces in contact with a liquid. Organic and inorganic material in the liquid sediment on to the solid material. Biologically active microorganisms are attracted to the solid surface and adhere to it for initiating growth for forming an attachment matrix for developing into a complex community. Such biofilms are common on solid surfaces in contact with many different kinds of liquids like fresh water, sea water, oil, milk and others. Cleaning and sanitizing practices generally focus on food contact areas and non-food contact surfaces are not given much attention where biofilms can form with potential for contaminating foods processed in the area. Bends in pipes, conveyor belts, cutting boards and tables, water recycling systems, filters and such areas are vulnerable to biofilm formation and subsequent spread of bacteria into the food materials. This is where food technologists will have to pay more attention to preempt such possibilities. Technology needs to be upgraded to include meeting the challenges posed by biofilms to the safety of processed foods coming out of factories and knowledge emerging about the QS properties of microorganisms will help in designing more reliable approaches to preempt any potential threat.


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