Page Banner

United States Department of Agriculture

Agricultural Research Service

Untitled Document

The Heat Is Off
Zapping Food Bugs — Without Heat

Pop quiz!

It’s summertime, and you’re heading to a barbecue. To make sure your food is safe, you should:

A) Leave the potato salad and deviled eggs in a hot car for a few hours.
B) Cook hotdogs and hamburgers quickly, or at a low temperature.
Skip washing the fruits and vegetables.
None of the above.


A is a bad idea! Potato salad, deviled eggs, and any foods that contain mayonnaise should be refrigerated as long as possible.
is wrong too. The easiest way to keep your meat safe is to make sure it’s heated to 160 degrees F for at least 5 minutes when you cook it. That kills any bacteria that might be on it.
is also bad. Wash or peel your fruits and vegetables to make sure they’re clean and safe.
is correct! To keep your food safe, you should refrigerate food, cook your meat very well, and wash your fruits and vegetables.

A lot of our food has microorganisms, or “germs,” in and on it. Microorganisms are living things, like bacteria, that are too small to see without a microscope. Some of them are actually good for us! For example, our stomachs are full of bacteria that help us digest our food. But some microorganisms can make us sick. So how do we avoid them? The easiest way is to practice safe eating habits. Remember: Food safety ROCKS!

Refrigerate foods and keep them cool.
nly eat fruit and vegetables that have been washed.
ook meat well.
eep your food away from insects and dirt.
Stay safe and enjoy your food!

Science can help make our food safe—even before it gets to the supermarket. Thanks to Agricultural Research Service scientists and their fancy equipment, our country has a very safe food supply.

One good way to make food safe is to heat it up. But heat can change the flavor and texture of your food. Sometimes this is a good thing—chocolate chip cookies are safer to eat than cookie dough—and they taste delicious! But sometimes heating up food makes it taste weird. So scientists use fancy equipment to reduce the number of microorganisms on, and in, our food without heating it up.

What kind of equipment do we use today? Howard Zhang [pronounced “Zong”] is a scientist in the Food Safety Intervention Technologies Research Unit, near Philadelphia, Pennsylvania. He and his colleagues study the technology we use to keep our food safe, including high-pressure processing, irradiation, and ultraviolet processing.

High-pressure Processing

Have you ever dropped something heavy on your foot? Lost a wrestling match with one of your friends? Swum to the very bottom of the pool?

If so, you know how it feels to have a lot of pressure on you—it hurts! High pressure can make people feel tired, achy, or sore, and bacteria don’t like it either. That’s why scientists use high-pressure processing (HPP) to keep your food safe from harmful bacteria.

If you’ve swum deep enough, you probably noticed that your head hurt and your ears popped. Scientists using HPP apply 80,000-130,000 pounds per square inch of pressure to a food sample. That’s more than 7,000 times the pressure you’d feel at the bottom of a swimming pool! That kind of pressure could crush you like a soda can, and it has a similar effect on bacteria. Scientists use it to kill bacteria in your food so that it’s safe for you to eat.


Certain kinds of radiation can kill microorganisms like bacteria, molds, and yeasts in your food — without changing its flavor, texture or smell. Chicken, eggs, shellfish and ground beef can all be made safer by this kind of treatment. In fact, irradiation is so effective that the U.S. government recommends it to treat ground beef in school lunches. Lots of food at supermarkets around the world has been irradiated to make it safe to eat too.

Ultraviolet Processing

Your parents probably tell you to wear sunscreen when you’re outside in the summer, and that’s great. Sunscreen protects your skin from ultraviolet (UV) light rays. Too much UV is bad for your skin—and for bacteria. Zhang and his colleagues found that UV light can get rid of bacteria in things like eggs and apple cider, making them safer to eat and drink.

If you spent a long time outside without any sunscreen on, you might get a sunburn because of the UV rays. When Zhang and his colleagues put food in front of UV light, they found that the light killed the bacteria but didn’t hurt the food. This is good news for us. It’s one more way to make food safer before we buy it.


By Laura McGinnis, Agricultural Research Service, Information Staff.

The Heat is Off Home: Click here to return to the homepage
Sci4Kids Home: Bridging the gap between science, agriculture, and you
ARS Home: Solving agricultural problems with science

Last Modified: 3/12/2007
Footer Content Back to Top of Page