The leaves are changing, the temperature is dropping, and as we slide fully into fall, the shift in season means one very important thing for foodies: It's apple season.

But did you know that the apples on the shelves of your supermarket might be nearly a year old? Here's why — and why it doesn’t necessarily mean you should panic.

Lauren Sucher, a spokeswoman for the Food and Drug Administration, confirmed to TODAY.com that apples on store shelves aren’t always as fresh as they seem.

“A number of commodities, including apples, may be stored to extend their availability for marketing,” she said. “In controlled temperatures and low humidity, apples can be stored for months before being consumed.”

According to the U.S. Department of Agriculture’s website, freshly picked apples left untreated will last a few weeks before they turn soft and rot, so they’re often stored under temperature-controlled conditions that allow them to last up to 10 months. Once they’re removed from storage, however, the clock starts ticking again.

“To slow the proverbial sands of time, some fruit distributors treat their apple bins with a gaseous compound, 1-methylcyclopropene,” the USDA states. “It extends the fruits’ post-storage quality by blocking ethylene, a colorless gas that naturally regulates ripening and aging.”

The same chemical is used to lessen the “de-greening of broccoli, browning of lettuce, and bitterness in carrots,” according to the USDA.

Trending stories,celebrity news and all the best of TODAY. This site is protected by recaptcha

But even if this fact is surprising, it shouldn’t be scary. Although antioxidants and taste may wane over time, experts tell TODAY.com that such treatments are perfectly safe.

For starters, off-farm facilities that store food for consumption in the U.S. must register with the FDA, and must comply with related safety requirements, Sucher says.

Prolonging the life of produce isn’t a new concept, either. “Before the current technology, people had root cellars to extend the shelf life and availability of food commodities such as apples,” Sucher added. “This common, widespread practice allows consumers to eat a wider variety of produce items for more months of the year now than in decades past.”

Phil Lempert, a consumerologist who’s also known as the Supermarket Guru, told TODAY.com via email that while apples can exist in cold storage for a year before being shipped to supermarkets, their shelf life once they’re in stores usually is “only days to a couple of weeks.”

Martin Lindstrom, author of “Truth and Lies About What We Buy,” told TODAY.com it’s more common for international supermarkets to sell apples that have been picked more than a year earlier, but that that's less often the case in the United States.

Of course, not all harvested apples go into long-term storage. Many are delivered to fresh markets. In addition, not all apples from storage appear in the produce section. They may be used to make juices, frozen pies and other types of processed foods, Sucher says.

But even if extending the life of apples is safe, a store-bought apple may not be the healthiest option.

“A fresh-picked apple is always going to have the optimal nutrient profile of vitamins and minerals,” said Madelyn Fernstrom, a diet and nutrition editor for TODAY. “Apples are especially rich in polyphenols, a type of antioxidant.”

Those antioxidants appear to disappear over time. The website Food Renegade cites research that claims a year-old apple may retain close to none of its antioxidant properties.

Fernstrom said there may be truth to the correlation between age and decreasing antioxidant value, but stated the use of ethylene doesn’t appear to be the reason for it.

“A recent study suggests that the amount of antioxidants in apples might drop with extended storage," she added, "because these antioxidants are found in the peel, not the flesh of the apple.”

Although it’s often difficult to determine which supermarket apples are freshest until after they’re bought, Lindstrom said some markets are working to provide better information about each apple. “Some retailers are now offering ‘footprints,’ telling [shoppers] when it was grown and when it was picked,” he added.

And if you don’t want to play that kind of guessing game? “Your best bet is to buy apples seasonally and locally,” Fernstrom said.

TODAY.com writer Chris Serico contributed to this story. Follow him on Twitter. Alesandra Dubin is a Los Angeles-based writer and the founder of home and travel blog Homebody in Motion. Follow her on Facebook, Google+ and Twitter.