Filling your cart with lots of fresh produce, from berries to leafy greens, gets a little bit tougher—and more expensive—during the winter when these items aren’t in season. Yet that doesn’t mean you should eat fewer fruits and vegetables during this time, so what’s a shopper to do? Many consumers will hit the frozen aisle to pick up staples such as frozen broccoli, spinach and cauliflower, or bags of frozen berries to add to smoothies.
But are these varieties as nutritious as fresh produce? It depends. But in some instances, frozen produce is actually fresher and more nutritionally dense than fresh. Here’s the lowdown.
Fresh vs. Frozen Fruit & Vegetables
How fresh is fresh produce, exactly?
“The majority of produce we see in a store are picked prior to their ripeness to account for days of travel to stores, and once in stores, it sits on shelves,” says Maura Rodgers, a registered dietitian nutritionist who runs her own practice. During this process, she continues, produce goes through chemical changes such as respiration and oxidation, which can significantly reduce nutrients.
For example, some fresh green vegetables such as spinach and green beans can lose up to 75 percent of their vitamin C a week after being harvested, says Rodgers—“and that’s even considering their environment is ideal, being refrigerated and stored with other produce of the same kind, so [nutrients] can drop even more [if that’s not the case],” she adds. All told, the produce you’re shopping at your supermarket may not be as fresh—or as nutritious—as you think.
Produce that's better fresh
The type of vitamins that a fruit or vegetable contains is a key indicator of whether it will be more nutritious fresh or frozen, says Rodgers. Produce containing water-soluble vitamins, such as vitamins B and C, will be better fresh, because during the freezing process, many of those vitamins can be leached out, she notes. That includes things like leafy greens and peppers.
Some produce, such as members of the brassica family (cruciferous vegetables, cabbages and mustard plants) are heartier and can withstand not being refrigerated for some time. This includes items such as kale, brussels sprouts and cauliflower, which are typically better fresh than frozen, says Rodgers. “Chilling these for a long period of time can inhibit or degrade some of their phytochemicals and antioxidants,” she says, “so eating those fresh is the best way to ensure you’re consuming them in their highest potency.”
On the other hand, produce such as spinach doesn’t retain its structure when left outside refrigeration, so it will become wilted and lose some of its nutrients quickly. “There’s a lot of food science behind why certain vegetables can maintain their structural integrity in room temperature, while others can’t,” Rodgers explains.
Produce that's better frozen
Produce containing fat-soluble vitamins such as A, D, E and K—which are stored in fat tissue in our bodies, and therefore best absorbed when consumed with a fat such as olive oil, nuts or seeds—are more stable frozen. This includes items such as carrots, apricots and sweet potatoes.
“Some studies have indicated that the antioxidant profile for vitamins A and E are greater in frozen foods compared to fresh,” says Rodgers. There is also research showing that other nutrients in certain kinds of produce, including vitamin C, polyphenols, beta-carotene and anthocyanins, are retained better in a frozen environment versus fresh, as the transportation process can lead these vitamins to leach out of produce.
It’s a great idea to buy fruit such as berries frozen, says Rodgers, especially during the off season. “The chance to compromise a fruit becomes significantly smaller [when buying frozen],” she says. When you compare frozen raspberries, strawberries and cherries to fresh versions in the supermarket, for example, the fresh version is likely to have been touched by many more hands, as well as potentially exposed to environmental chemicals and toxins. For this reason, Rodgers recommends buying berries frozen whenever a local farmer’s market isn’t an option.
Why cooking method matters
Regardless of whether you’re consuming fresh or frozen produce, how you cook it can also influence how nutritious the final product is. For example, produce containing water-soluble vitamins can lose many of those vitamins when cooked in water. “It’s important not to boil things like broccoli,” says Rodgers. “Time, intensity and heat leaches out those key water-soluble vitamins, and that’s why your water becomes green.”
Instead, you should always steam vegetables high in vitamins B and C, which will maintain the integrity of the vegetable as well as preserve the nutrition of that product.
How to use frozen produce
Aside from simply steaming frozen vegetables in their plain form, there are many ways to use frozen produce in appealing ways. One of the most obvious is smoothies: Rodgers will add frozen berries, along with a handful of frozen vegetables such as broccoli or spinach. “That way you’re getting good fiber and a lot of antioxidants, and you can pair them with more protein-filled ingredients,” she says.
You can also roast frozen vegetables like you would fresh in the oven, or add them to a stir fry on the stovetop, advises Keri Glassman, a registered dietitian and nutritionist with Kidfresh. “They may not have the crunch factor you can get with fresh,” she says, “but be patient and give them enough time to crisp thoroughly, and you’ll get delicious veggies.” In addition, you can steam frozen veggies in the microwave with just a little water, then throw them cooked into things like chilis, soups, sauces and lasagna.