Your dietitian: Fresh vs. frozen produce

"Fresh is best" is a motto most health-conscious people, including myself, have followed for years. Now researchers have discovered that may not be true for all fruits and vegetables. In fact, the nutrients in some produce is the same or higher in frozen produce than fresh — depending on the type of produce and how long after harvesting a fruit or vegetable is eaten. Here are the surprising findings. Significant loss of vitamin C in fresh produce In the winter, locally grown fresh fruits and vegetables are not in season in Ohio. Fresh produce must be shipped in from afar. The amount of time fresh fruits and vegetables are stored after being picked determines the amount of loss of nutrients — especially vitamin C. Vitamin C is the most easily lost nutrient. Heat, light and air cause vitamin C loss. As an antioxidant, it starts combining with oxygen in the air immediately after being harvested. For example, studies have shown that green peas lose up to 51 percent of their vitamin C during the first 24 to 48 hours. Significant reductions in the vitamin C content of other vegetables, such as green beans and broccoli, have also been found. The vitamin C content of fruits and vegetables continues to decrease during storage. In the U.S., fresh fruits and vegetables may spend three days to several weeks in transit before reaching a distribution center. During transportation, fresh produce is held in temperature-controlled environments and usually treated with chemicals to retard spoilage. Holding produce at lower temperatures reduces the loss of vitamin C — since more is lost at room temperature. Once at the grocery store, produce may be on display (at room temperature) for one to three days, or more. Then, it is stored in people's homes for another few days (or more) before being eaten. Some produce, such as apples and pears, are harvested in the fall, but may be stored for up to 12 months. (Apples and pears are not rich sources of vitamin C.) Freshly picked strawberries, one of the most-popular fruits, are a rich source of vitamin C. California strawberries take three to four days to arrive in stores, then may be on display in stores at room temperature for a few more days until they are stored in your refrigerator. Studies have found that in just five days after being harvested, the vitamin C in fresh strawberries decreases from 61 mg to just 7.5 mg in 100 grams (3.5 ounces) when held at room temperature, to 43 mg when refrigerated and to 45 mg when frozen. Thus, the only way to obtain strawberries high in vitamin C is to purchase them at a same-day picked farm stand or pick-your-own berry farm. In the winter, frozen strawberries may be the best choice. Bell peppers are even higher in vitamin C. As fruits and veggies ripen on the plant, the amount of vitamin C increases. That is why orange and red peppers, which take longer to ripen, contain more vitamin C than green bell peppers. (One half-cup of diced orange bell pepper contains a whopping 138 mg vitamin C.) Interestingly, red bell peppers refrigerated for up to 20 days lost only 15 percent of their vitamin C, per research studies. Oranges are well-known for their vitamin C. Due to their thick peel, oranges don't lose vitamin C after harvesting. So eating a navel orange, with its 83 mg of vitamin C, is a terrific way to get this nutrient during the winter. However, orange juice sold in clear bottles can lose vitamin C due to light exposure. For the most vitamin C, eat whole fresh navel oranges and/or make freshly squeezed juice from fresh oranges. Frozen vegetables Prior to freezing, vegetables are plunged into boiling water (blanched). This is done to destroy harmful bacteria and the vegetable's natural enzymes which would cause discoloration and a change in texture upon freezing. Although blanching destroys vitamin C, it does not destroy the fiber or fat-soluble nutrients in vegetables such as Vitamins E and K, beta carotene (which the body converts into vitamin A), and its minerals. Researchers found no difference in the levels of these nutrients between fresh and frozen vegetables. Therefore, vegetables such as frozen carrots, corn and mixed vegetables are just as nutrient rich as fresh. (These veggies are not good sources of vitamin C.) Interestingly, blanching (boiling) deactivates the enzymes which degrade (break down) beta carotene in carrots. It also breaks down the woody cell walls in carrots to release more beta carotene from absorption. Studies have shown that cooking carrots releases 14 percent more beta carotene for absorption. Thus, you get more nutrients from cooked carrots than from raw ones. Fresh spinach and broccoli bestSince vitamin C dissolves in water and is not heat resistant, a significant amount of vitamin C may be lost during blanching. For example, studies found a vitamin C loss of 30 percent in frozen peas and 50 to 88 percent loss in frozen spinach. So, while frozen peas are a good choice, frozen spinach is not. According to Harvard Health, spinach should be eaten raw to obtain the spinach's rich supply of lutein (an antioxidant for preventing macular degeneration) and vitamin C. Chopping spinach releases the lutein held within its plant cell walls and makes it available for absorption. Plus, as fat-soluble nutrients, fat is needed for absorption of spinach's lutein and its vitamin K. Thus, adding extra virgin olive oil or a full-fat salad dressing to spinach is needed to absorb spinach's nutrients. Similar to spinach, fresh broccoli is a better choice than frozen. Blanching broccoli prior to freezing destroys broccoli's vitamin C. It also destroys the enzyme necessary to convert its isothiocyanates into broccoli's anti-cancer compound called sulforaphane. Thus, eating frozen broccoli does not reduce the risk of cancer. To obtain broccoli's anti-cancer benefit, choose fresh broccoli. Then, eat it raw or steam it for only three minutes so as not to destroy broccoli's enzyme. Frozen berries & cherries bestFruits are frozen on the same day as they are harvested. Thus, they do not lose their nutrients during storage or transportation. In addition, fruits are not blanched (boiled briefly) before freezing. Freezing does not destroy nutrients. Dark-colored cherries and berries, especially blueberries, are rich in the powerful anthocyanin antioxidants which reduce the risk of dementia, heart disease and other ailments. The anthocyanins are in the dark pigment of the skin of fruits. Therefore, smaller-sized fruits such as wild blueberries provide more skin and thus, more anthocyanins. Surprisingly, freezing has been shown to more than double the concentration of anthocyanins in blueberries per a study at South Dakota University. Researchers believe that the ice crystals break open the cell walls on blueberry skins, allowing more of the anthocyanins in the skin to be released. Therefore, more can be absorbed when we eat the blueberries. High temperatures, such as in baking, destroys anthocyanins. Therefore, to get the most health benefits out of frozen berries and cherries eat them thawed, but uncooked. Use frozen cherries and berries to make delicious smoothies (see recipe). Or mix them with a bit of sugar to top waffles, pancakes or French toast. Of course, thawed berries and cherries are delicious atop vanilla yogurt in parfaits or vanilla ice cream in sundaes. For supper, try topping a kale salad with thawed frozen blueberries. The sweet berries pair wonderfully with the kale, crunchy almonds and salty feta. It's delicious with either ranch dressing or a homemade citrus vinaigrette (see recipe). Or, make a pretty blueberry sauce to top baked salmon (see recipe). For a truly nutrient-rich and delicious treat, try one of my favorite breakfasts. Top hot oatmeal with (thawed overnight) frozen wild blueberries and a big squirt of whipped topping. Delicious! Thus, although fresh spinach and broccoli deliver more nutrients and thus health benefits than frozen, it turns out frozen berries are the healthier choice than fresh. What a surprise! Blueberry smoothie1 cup frozen blueberries½ cup orange juice½ cup vanilla yogurt (or one 5.3-ounce carton of vanilla Greek yogurt)1 teaspoon honey or sugar Place all ingredients into a blender. Process until smooth, about 1 minute.Serve immediately in a tall glass. If desired, garnish with blueberries on a skewer with a spiral of orange peel. Delicious and pretty!Note: This was my mother-in-law's favorite smoothie. It's really delicious.Makes: 1 servingSOURCE: www.blueberrycouncil.org Salmon with Blueberry Balsamic GlazeBlueberry balsamic glaze½ cup pomegranate juice, no sugar added¼ cup balsamic vinegar¼ cup sugar, or less to taste1 cup blueberries, preferably thawed overnight, frozen wild blueberries Salmon4 (4 to 5 ounce) wild salmon fillets, thawedAbout 1 tablespoon olive oilDash of each: salt, pepper, onion powder, dill1 teaspoon lemon zest, optional garnish Preheat oven to 350 degrees. Line a baking pan with foil for easy clean-up.Spray foil with cooking oil spray or lightly grease.Drizzle oil on each fish fillet. Sprinkle each fillet with seasonings.Bake for about 15 to 20 minutes or until fish flakes easily with fork and internal temperature reaches 145 degrees. Prepare blueberry glaze while fish bakes.Pour pomegranate juice, balsamic vinegar and sugar into a saucepan. Cook for 4 to 6 minutes, stirring constantly. Once sauce stars to thicken, cook an additional 2 to 3 minutes. After the sauce is reduced it will have the consistency of maple syrup. Add blueberries and a dash of salt and pepper. Serve sauce over cooked salmon and garnish with lemon zest if desired.Serves 4Delicious served with microwaved mini red potatoes and steamed fresh broccoli.Note: If cooking for two, simply bake two salmon fillets and use half the sauce.Refrigerate remaining sauce for use at a later date. Sauce keeps well in refrigerator. Source: Giant Eagle grocery store Blueberry kale salad with citrus dressing for one¾ cup shredded kale, center ribs removed2 tablespoons feta cheese2 tablespoons sliced almonds, toasted if desired¼ cup blueberries Citrus dressing:1 teaspoon each: lemon juice and orange juice3 dashes of salt 2 dashes of black pepper1 dash onion powder (or ¼ - ½ teaspoon minced shallot)¼ teaspoon honey1 tablespoon extra-virgin olive oil Wash kale. Pat dry with a paper towel. Remove the center rib. Stack leaves and cut into thin strips. Place in a salad bowl. In a small bowl, mix together juice, salt, pepper, onion powder and honey. Slowly drizzle in olive oil while mixing with a whisk. Pour dressing over kale. Massage kale with clean fingers to tenderize and remove its bitterness. Do not skip this step. Top salad with feta cheese, almonds and blueberries. Enjoy!Makes: 1 serving (Recipe can be easily doubled or tripled.)SOURCE: Citrus dressing based on a recipe by Pamela Salzman