It’s important to keep kitchen cloths clean to avoid spreading bacteria from one food to another.
After learning all about microscopic life in your food, you might be getting a little concerned. Don’t worry—most food is safe and healthy most of the time. And there are things you can do to make sure you keep your food free from microscopic invaders.
Keeping clean
Many kitchen bacteria are helpful or at least harmless. They will compete with harmful bacteria to keep food safe. You can help, too, by keeping things clean, and the most important thing to keep clean is you! Bacteria will travel quickly from your skin onto food. It’s really important to wash your hands after petting animals, using the bathroom, and playing outside. Never forget to wash your hands before touching food.
You may be surprised to know that the sponges and cloths we use for cleaning hold more bacteria than anything else! Bacteria can spread from a sponge to a dish and then to your food. Sponges and cloths need to be washed in very hot water or even heated in the microwave for two minutes to kill bacteria.
Hot and cold
Bacteria multiply faster in warm conditions. To slow decay, keep meat, produce, and dairy foods in the refrigerator or freezer. Proper heating and cooking will kill bacteria altogether. For example, Salmonella in eggs, chicken, and red meat die when these foods are thoroughly cooked.
As we saw earlier, bacteria absorb their food from other livings things or from decaying matter. Many bacteria can digest protein, so they live on meat. With the right supply of food, bacteria multiply quickly, so a small piece of meat can hold millions of bacteria.
Food poisoning
We know that most bacteria are harmless and even useful. But some of these microscopic organisms can also be very harmful. Several bacteria that infect meat can give people food poisoning. Most kinds of food poisoning have the same horrible symptoms. People feel nauseous, and they vomit a lot. They get really bad stomachaches and diarrhea. People usually recover after a few days, but sometimes they develop more serious illnesses.
Bad bacteria
Let’s look at some of the bacteria in meat that make us sick. Salmonella bacteria can invade all kinds of meat.
They are common in chicken, so eggs can be infected, too. It takes fewer than 20 Salmonella cells to make someone sick. Campylobacter jejuni is even more common than Salmonella in chicken. People infected with this bacterium get terrible diarrhea. Usually it goes away by itself, and people may not know what caused the illness.
Good and bad E. coli
Some forms of the bacterium Escherichia coli (E. coli for short) are healthy. They live in our intestines and fight other, harmful bacteria. But one type of E. coli that lives in cattle intestines can make people sick. When beef is ground into hamburger, the E. coli often infects meat and gets passed on to humans. Other harmful types of E. coli come from infected chicken or even vegetables.
Antibiotics are substances that can kill bacteria in your body. We use them as medicines when we get sick from bacterial infections. In the photo below, an antibiotic is destroying an E. coli cell wall. Farmers and ranchers add antibiotics to animal feed to prevent illness in cows, pigs, and sheep. But some bacteria are getting so used to antibiotics that the antibiotics can’t kill them anymore. So when bacteria cause infections, antibiotics may not be able to kill the bacteria and make people better.
The smallest and most plentiful microorganisms in our food—and in the world—are bacteria. Even though you can’t see them without a microscope, bacteria are everywhere.
What are bacteria?
So what are these microscopic life-forms? Unlike plants and animals, bacteria are made of a single cell. You can see a typical bacterium below and take a look inside its cell. Bacteria often live in large clumps called colonies. They multiply constantly by dividing their cells.
Most bacteria are shaped like rods,but many are round. Others are bent or shaped like spirals. Bacteria also vary in size, but most measure between 1 and 4 micrometers across.
Whatever shape bacteria are, the insides of their cells hold the same basic parts. On the outside, some bacteria have pili to hold onto the cells of their food source. The larger hairs are flagella, which many bacteria use to move around.
Hungry bacteria
Bacteria need food to survive. Mostly they live on organic matter—food that comes from living things—just like we do. As bacteria digest food, they change the food they are eating.
Living in milk
Milk contains bacteria called lactobacilli that live on lactose, the sugar in milk. When milk goes sour, it’s because lactobacilli are producing a sour substance called lactic acid as they feed. Nobody wants to drink sour milk, but we can use the bacteria in milk to make food we do like. Next you will see how bacteria and fungi together help make some of our favorite foods!
Bacterial Names
Scientists use the term bacilli to describe rodshaped bacteria and cocci for bacteria shaped like spheres. These bacteria shapes are common in milk. Lacto means milk, so some milk bacteria are named lactobacilli and others are lactococci.
