Amid outbreaks of listeria in salads and fruit… food safety expert explains how to spot rotten produce and what you can do to keep groceries fresher longer

Foodborne illness sickens tens of thousands of Americans every year, with fruits, vegetables and meats all becoming contaminated with bacteria that can cause serious medical complications.

Illnesses resulting from spoiled food include norovirus, salmonella, E. coli and listeria – all of which can cause fever, vomiting, cramps and diarrhea. There are millions of cases of this every year in the US, leading to tens of thousands of hospital admissions for the most critical patients.

Food can be exposed if it comes into contact with surfaces or water containing animal feces.

Although produce spoils before it reaches the store and before it is stored in your pantry, there are still food safety risks once your groceries arrive home.

Food scientist Brittany Towers Lewis shares “Science in 60 Seconds” posts on her TikTok, providing followers with nutritional science and safety facts ranging from tracking expiration dates to what to do with rotten bananas.

Lewis told CNN that there are four important things to keep in mind when trying to maintain the freshness of your fully stocked kitchen: time, oxygen, moisture and light.

To prevent foodborne illness and extend the shelf life of your groceries, Lewis told CNN there were four important things to consider when trying to maintain the freshness of your fully stocked kitchen: time, oxygen, moisture and light.

Lewis said, “Obviously the longer you keep something, it will eventually spoil.”

In one of her “Science in 60 Seconds” videos, Lewis said that while it’s important to keep the expiration date in mind, it’s not the most important thing.

She said following the expiration date on a food’s packaging depends on a number of aspects, including how the food has been stored and what the food is.

If a product has passed its expiration date, you are unlikely to need to throw it away.

She explains: ‘Companies put expiration dates on foods to give consumers an indication of when the quality of a product may deteriorate.’

However, there are many aspects that can cause food to spoil before its expiration date, or keep it fresh longer than the date on the package.

More important than strictly following the date, Lewis advises people to use their senses.

She said: ‘If it smells, looks or tastes funny, you should probably throw it away.

“That said, foods can go past their expiration dates. So our senses can help us stay safe and also help us reduce food waste.

“So keep in mind that you should use the expiration date as a guide, but that is not the gospel truth.”

Lewis explains that oxygen can play a major role in food quality over time.

There are many reactions that can occur when food is exposed to air, including oxidation. Oxidation is the process responsible for the deteriorating quality of food products, including bad flavors and bad odors.

It also causes some cut foods to turn brown, such as apples.

Another process that can cause food to brown and spoil is the release of ethylene, a gas that causes fruits and vegetables to ripen.

If you’ve ever been advised to put food in a bag with bananas so it ripens faster, that’s because bananas are climacteric foods: foods that produce ethylene.

So if you want to keep products for as long as possible, Lewis recommends keeping items separate and away from each other.

The third important food safety aspect Lewis mentions is moisture, which increases microbial growth.

Lewis said exposure to moisture should be avoided as it can lead to bacterial and mold growth on food.

An important item to keep dry is lettuce, but only after you rinse it first.

Lettuce is a common culprit of foodborne illnesses, such as listeria and E. coli. To keep your salad greens from spoiling before you have a chance to use them, Lewis told Rinsing your leaves with a mixture of water and vinegar can help, but make sure you dry them thoroughly afterwards.

Lewis said: ‘If you find that your leaves are not lasting very long, the best way (to preserve them) is to rinse them (with the mixture) and then make sure they are completely dry.

“Vinegar not only helps kill or monitor bacteria, but it is also very acidic and most bacteria do not like acidic environments.”

Keeping moisture out is also crucial, Lewis added: ‘Bacteria love water and that’s what they use to grow. The more water you try to get out of the leaves, the longer they last.’

To do this, you can place a paper towel in the storage container with your lettuce so that it can absorb some moisture.

In her latest advice, Lewis explains that light can cause food to spoil more quickly. For example, when potatoes are exposed to light, they can turn green and grow sprouts.

To prevent your potatoes from growing new parts, keep them in a cool and dark place.