1963

Irradiated Food

Frozen pizza entered the marketplace in 1957, but there are many foods that cannot be frozen. Think about the refrigerated food section in any store. The food is packaged, yet it still needs refrigeration. The reason is because it contains bacteria. If your grocer left milk out on a shelf rather than refrigerating it, it would spoil in a few hours. At room temperature, the bacteria in the milk multiply rapidly and ruin it. The same is true of most dairy products, meats, premixed cookie doughs, and biscuits, etc.

What if engineers could develop a technology to eliminate the bacteria in packaged foods? It turns out they have—it is called canning. If you heat a can or jar of food to a sufficient temperature and then seal it, the contents are sterile. This makes the food shelf-stable, and it explains why things like spaghetti sauce and canned vegetables do not need refrigeration. The problem with canning is that the heat can change the taste and texture of the food.

What if engineers could develop a technology to eliminate the bacteria without changing the taste? This technology exists and it is called food irradiation, first approved by the US Food and Drug Administration (FDA) in 1963. Using this process, it is possible to seal fresh meat in a plastic wrapper, irradiate it to kill the bacteria, and then leave it on a shelf for a year or more. Inside its wrapper the meat is sterile, so bacteria do not spoil it. When you unwrap it, it is a piece of fresh meat.

Gamma-ray irradiation is one popular technique. Cobalt-60 is a gamma ray source and meat passes near the source to irradiate it. The process is extremely simple. The main engineering challenge is keeping people away from the radiation and keeping the radiation sources secure. Since gamma rays are high-frequency, ionizing radio waves, they pass through the meat like radio waves would, killing the bacteria while leaving nothing behind.

Irradiation technology has existed since the 1960s. NASA uses it on meat flown in space. But the technology is used on only a small number of foods. Why don’t we see it commonly in grocery stores? The reason is something engineers can’t do anything about: fear. When people hear the word “radiation,” there is an immediate negative reaction, despite the safety and benefits of the process.

SEE ALSO Electric Refrigeration (1927), Microwave Oven (1946), Frozen Pizza (1957).

This photo shows irradiated strawberries (left) and normal strawberries (right) after several days.