Monday, August 22, 2011


Here comes another "tall" claim from the scientific community regarding the discovery of a natural substance that can protect foods at room temperature without any need for heating, chemicals, radiation, freezing or other known preservation technologies. Of course they are not referring to the age old natural preservatives, organic acids, salt or sugar, all of which can preserve foods at relatively high concentrations. The new preservative substance is extracted from a bacteria which was found to be effective in killing 99% of the pathogens that commonly affect food products. While nisin, a bacteriocin of proven efficiency, is a well known preservative used widely in Cheese, whether the new preservative reported is as good as or better than it, is not certain. But the claim that it can preserve foods at ambient conditions for long is debatable because food spoilage is not entirely due to microbial action and chemical changes occurring at non-refrigerated temperatures can make the food unacceptable from sensory angle.

"There would also be no need to refrigerate produce treated with the preservative, called, bisin, which is produced by harmless bacteria. They say that foods like milk, sausages and sandwiches containing the agent could be on the shelves within three years. Ready meals, opened wine and fresh salad dressing could also be safely consumed long after they were bought, say scientists. Researchers at Minnesota University in the US discovered the substance from a culture of a harmless bacteria, Bifodobacterium longum, commonly found in the human gut. It is the first naturally occurring agent identified that attacks so-called gram-negative bacteria such as E.coli, salmonella and listeria".

"Bisin is related to nisin, which attacks gram-positive bacteria, and is used in the manufacture of processed cheeses and meats. As such, it is generally recognised as safe and would not have to be pharmacologically tested. It would not be able toprevent fruit and vegetables from rotting, however, as they decompose in a different way. Further research is now ongoing, looking at exactly how good it is at stopping bacteria from growing. Meanwhile, a British wholesaler has begun to make sandwiches with a two-week shelf life, by replacing all the oxygen in the plastic packaging with nitrogen and carbon dioxide. Ray Boggiana, a food technologist who helped develop the range for Booker, which supplies convenience stores, said: "The science is not new. It's all about using a protective atmosphere in the packaging."

There is nothing like a scenario in which foods can be stored for years together without any deterioration and it is doubtful whether man will ever come up with such a technology. Of course freezing is the nearest process conforming to the above perspective but here also changes do take place albeit at very low pace. Probably new antibacterials derived from bacteria, numbering about 30 at the present count, including nisin and bisin may have a better prospect if used in synergy with some of the currently practiced technologies. India should have a strong interest in these bacteriocins because many traditional foods popular in the country may be amenable to preservation using these substances. It is the duty of the Indian food scientists to work in this line for perpetuating many of the popular heritage foods through generations to come.

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