Roots of Irradiation
Although food irradiation is often referred to as a cutting-edge technology, its beginnings stretch back nearly a century. A few years after radiation was discovered by French physicist Antoine-Henri Becquerel in 1896, Samuel Prescott, professor of biology at MIT, showed that gamma rays from radium destroyed bacteria in food and proposed using radiation to preserve meat, fruit, vegetables, grains, and other foodstuffs. In the 1920s and 1930s, the United States and France awarded patents for radiation-based methods of killing parasites in pork and bacteria in canned food. Some 25 years of research at MIT and U.S. Army research facilities-from 1943 to 1968-further demonstrated its potential for treating and preserving food.
This high-tech cousin of canning, freezing, and fumigating relies on a simple principle that children of the atomic age know by heart: radiation kills, or at least alters, living cells. When gamma rays or other types of ionizing radiation zip through a cell, they knock some electrons out of their orbits, breaking chemical bonds and leaving behind a trail of ions and free radicals-atoms or molecules with an unpaired electron. These highly reactive substances crash into each other and into their nonirradiated neighbors, creating some new compounds and reforming many that had originally been there.
When a cell is exposed to high enough doses of radiation, the maelstrom of chemical reactions inside an irradiated cell inactivates key enzymes, irreparably damages the cell’s genetic instructions, and can disrupt its protective outer membrane. The cell either stops growing and fails to reproduce or dies outright. Either of these outcomes destroys organisms that are natural or introduced contaminants of food or other products or prevents them from multiplying.