Sun bathing: Conventional drying leads to microbial onslaughts

Although India is one of the largest producers of onion, lentils, cereals and vegetables, an average Indian does not consume much of those food items. And poverty is not the only deterrent to his or her access to them; rather, it?s the post-harvest decay ? including insect infestation, contamination due to tropical humidity and natural changes like rotting and sprouting ? which pose problems for their consumption. Food products worth over Rs 10,000 crore could have been saved had there been an effective application of scientific preservation techniques like irradiation.

Food irradiation is a processing technique with similar results to freezing and pasteurisation in which food is exposed to ionising energy, or radiation. At low doses, irradiation extends a product?s shelf life. At higher doses, this process kills insects, moulds, bacteria and harmful micro-organisms.

It?s been years since scientists at the Bhabha Atomic Research Centre (BARC), Mumbai, had developed irradiation technology to preserve perishable food products. Albeit late, entrepreneurs in private and co-operative sectors are coming forward to implement the sterilisation technique. Next week Vikiran, the country?s most sophisticated gamma irradiation processing plant, will be inaugurated at Dankuni near Calcutta. In collaboration with the Board of Radiation & Isotope Technology (BRIT), and monitored by the Atomic Energy Regulatory Board (AERB), it will use the cobalt-60 isotope to sterilise a wide range of products, including food, pharmaceuticals, surgical instruments and herbs.

?One of the most widespread application of irradiation will be spice sterilisation,? says J.K. Ghosh, CEO, BRIT. ?Spices get contaminated with disease-causing bacteria during the conventional sun-drying procedures. Contamination arises from excreta of insects, birds, rodents etc. from wind-blown dust in open areas.?

?Irradiation techniques at the new plant will arrest sprouting in onions and potatoes and delay the ripening of fruits such as mangoes, bananas, and papayas,? says P.J. Chandy who works for BRIT. ?It will disinfest grains, extend shelf-life of fish and meat and eliminate fatal microbes from seafood.?

The advantage of using gamma irradiation is that it can penetrate products in the fully-packaged form. Being a cold process, heat-sensitive plastic packs can also be sterilised with little damage. Chemical changes brought about by irradiation are minor compared to the changes caused by cooking.

Satadal Chatterjee