It's only if the odour is terrible, you'll decide it's teeming with food poisoning bugs and is best tossed in the bin. While this is a common strategy, it's actually a pretty lousy one, food experts say. Food can look, smell and taste just fine but still contain enough food poisoning bacteria to make you very sick, Ms Buchtmann says. On the other hand, if food smells off, you're right in thinking it's a good idea not to eat it.
When a plate of leftovers starts to pong, it means spoilage bacteria have taken hold. When spoilage bugs are at work, it's the start of the rotting process by which food decomposes, Ms Buchtmann says. While spoilage bugs are different from the microbes that cause food poisoning, if conditions are right for spoilage bugs, there's a good chance the food poisoning bugs have grown too. That means you may well be risking a nasty bout of stomach cramps, diarrhoea, and vomiting that could see you laid low for days.
So the nose test is right in that if it stinks, it's best to toss it out. But never assume that just because it smells fine, it's fine to eat. So how can you know if leftovers are safe to eat? Unfortunately, there are no iron-clad guarantees, Ms Buchtmann says. Labelling your parcel of goodies with the date before you stow them in the fridge is a good start. Most leftovers should keep two to three days in a fridge maintained at the right temperature 5 degrees Celsius.
If you don't think they'll be eaten in that time, consider freezing them. They may also begin to turn colors, smell bad, and taste even worse! What causes these changes within foods? Some of the primary culprits are air, moisture, light, temperature, and microbial growth. When two or more of these culprits get together, they can accelerate the spoiling process even further.
When food is exposed to air, microorganisms can land on the food and begin their work of breaking down the food for their own uses. The presence of oxygen enhances the growth of microorganisms, such as molds and yeasts, and contributes directly to deterioration of fats, vitamins, flavors, and colors within foods through the work of enzymes.
All food is made up of a certain percentage of water. Over time, microorganisms use the water within food to fuel the chemical reactions they need to dissolve the food for energy and growth. Moisture on the outside of food also allows molds and other microorganisms to grow on the outside of food, as well as within any cracks or holes in the surface of the food, further contributing to increased decay.
When food is exposed to light, its outer layers can begin to spoil in a process known as photodegradation. Photodegradation can result in discoloration, as well as loss of flavor, vitamins , and proteins. Temperature also plays a role in food spoilage. As temperature increases, the chemical reactions that drive the spoiling process accelerate. That's why putting foods in the refrigerator or freezer helps to slow down the rotting process.
The process of food spoilage isn't all bad, though. It's a natural process that allows nutrients from the foods, as well as seeds, to be released and used again by living organisms in the environment. These processes are also key to creating some of the foods you love. While no one wants to drink spoiled milk, the souring of milk is an important step in the process of making cheese!
Since most of us do not grow our own food today, we must take steps to prevent food spoilage, so that food will last long enough for it to be transported to a store where we can buy it and bring it home to cook and eat. Scientists and researchers have helped develop many tactics over the years to fight against the main causes of spoilage, such as air, chemical reactions, and microorganisms. If you've been to a grocery store recently, you know that food comes in a wide variety of packaging.
That's not all just for show. Food packaging helps to protect it from the air and light. Controlling temperature by refrigerating and freezing foods also helps to slow down chemical reactions.
Finally, the battle against microorganisms is often fought by adding chemicals known as preservatives to food. These chemicals help to inhibit the chemical reactions that allow microorganisms to break down food for energy. We hope today's Wonder of the Day didn't spoil you! Keep learning even more when you check out the following activities with a friend or family member:.
Hi matthew. Hi, anna! There are a couple of different chemical changes that can cause food to rot. The cell walls of fruits and vegetables can break down, air can cause microorganisms to land on food and break down the food, water can help microorganisms dissolve the food for energy and growth, and light and temperature can also cause chemical changes in food. Thanks for asking, Richard! We ask that Wonderopolis be listed as the author.
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Good question, John! We encourage you to take a little Wonder Journey to see if you can find the answer to your question. Let us know what you come up with!
Thanks for asking, Iayan! Accessed 28 Feb. Great question! We believe it would just be referred to as "decomposing. That's a great question, Anonymous! Many food items have a "best by" date while others have a "sell by" date. When foods have a "sell by" date, it doesn't necessarily mean you must eat it by that same date.
It's probably good for a few more days. So, depending on the food, your dad is probably right. Hi, Marcos! We're glad you stopped by Wonderopolis to find ideas for your science project! We encourage you to check out the Try It Out activities above. Also, there are more than 1, Wonders you can explore for more ideas! Hello, kelly! Foods that deteriorate and develop unpleasant odors, tastes, and textures are spoiled. Spoilage bacteria can cause fruits and vegetables to get mushy or slimy, or meat to develop a bad odor.
Most people would not choose to eat spoiled food. However, if they did, they probably would not get sick. Related Information Title. URL Name. How can I control my appetite? How do birds survive storms and other harsh weather? How do bacteria become resistant to antibiotics? Is there a way to slow down that process? Skip to main content. Ask the Expert Why does rotting food smell bad? Benjamin E. Wolfe, an assistant professor of biology at Tufts, tracks down microbes for an answer.
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