Food safety 101: How does food spoil?

200267362-001It’s a familiar scene – you open the fridge and there, in the back corner, sits a lone container. You know when you put the container in the fridge, it contained some leftover casserole. Now, three weeks later, the once-forgotten tub might hold something that’s a bit more nefarious.

From there, a mad dash to the garbage can ensues to dispose of the spoiled blob that used to be a delicious treat. But how did that happen? What causes food to spoil?

Food is made up of organic matter, including microorganisms, many of which are harmless. As food sits, these microorganisms proliferate and chow down, causing food to “go bad” (e.g., getting slimy or the presence of mold indicates microbial growth). Getting rid of microbes is one reason humans cook food – the heat kills them. Proper cooking is especially important for killing harmful bacteria, such as E. coli and Salmonella, but bacteria that are transferred to the food after cooking can begin to grow.

Since most microbes grow best at temperatures above 40°F, putting food in the fridge helps slow bacterial growth and prolongs the window in which people have to consume food before it spoils. In fact, temperatures between 40 and 140°F are collectively known as the “danger zone” for bacterial growth. Although spoiled food may be off-putting (e.g., smelly, etc.), it doesn’t necessarily mean it’s dangerous.

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