Who doesn’t apprecaite the convenience of frozen produce every once in a while? It’s ready to cook, requires zero prep, and there’s no risk of losing a finger while choppng away. Since it’s National Frozen Food Month, we want to dig a bit deeper: With so many options lining the grocery store aisles, choosing how to buy veggies (and then prepare them once at home) can be mind boggling. But when nutrition is the deciding factor, what’s the best way to get the biggest bang per nutritional buck?
But this doesn’t mean that fresh produce is immune to nutrient loss — and the farm-to-grocery store process may be to blame. The freshness of a ripe tomato or strawberry isn’t measured from when it hits the grocery store shelf — it begins right after harvesting. Once a fruit or veggie is harvested, it begins to release heat and lose water (a process called respiration), impacting its nutritional quality. Between pest-controlling sprays, transportation, handling, and plain ol’ time, fresh produce at the store might have lost roughly half it’s original amount of nutrients.
The bag is mixed on whether cooked veggies are any “worse” nutritionally. Some research suggests cooking bright veggies (like tomatoes, carrots, and sweet potatoes) can also obliterate essential nutrients (specifically, carotenoids)Micellarisation of carotenoids from raw and cooked vegetables.Ryan, L., O’Connell, O., O’Sullivan, L., et al. Department of Food and Nutritional Sciences, University College Cork, Cork, Republic of Ireland. Plant Foods for Human Nutrition, 2008 Sep;63(3):127-33.. But other studies show the overall nutritional quality of a cooked veggie depends on the type of cooking. Despite the common notion that cooking kills nutrients, boiling or steaming some veggies (like broccoli and carrots) may actually boost levels of free radical-trapping antioxidants and phytochemicals like carotenoids and polyphenolsCustomized cooking method improves total antioxidant activity in selected vegetables.Ng, Z.X., Chai, J.W., Kuppusamy, U.R. Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. International Journal of Food and Science Nutrition, 2011 Mar;62(2):158-63.. However, methods like stir-frying have been found to deplete key nutrients like chlorophyll, protein, and vitamin C in broccoliEffects of different cooking methods on health-promoting compounds of broccoli.Yuan, G.F., Sun, B., Yuan, J., et al. Department of Horticulture, Zhejiang University, Hangzhou, China. Journal of Zhejiang University Science, 2009 Aug;10(8):580-8..
The best bet for cooking veggies to get the most nutrients for your buck? Go easy on the temperature and cooking time, and limit the amount of water you use for cooking veggies loaded with vitamins B and C (remember, water soluble vitamins will quickly vanish in the presence of H2O).And here’s some good news for the microwave chef: Studies suggest microwaves have little effect on the nutritional quality of fruits and veggies, much like conventional ovensThe effect of microwaves on nutrient value of foods.Cross, G.A., Fung, D.Y. Critical Reviews of Food Science and Nutrition, 1982; 16(4):355-81..
Foods with high amounts of vitamins B and C are best fresh because the vitamins are water-soluble, meaning they’re usually dissolved in food processing. In the fresh produce section, go for bell peppers, citrus fruits, cabbage, and berries.
Studies suggest frozen veggies have just as many nutrients as (if not more than) their fresh counterparts.
Foods that are best frozen are those with high amounts of fat-soluble nutrients, like vitamin A, carotenoids, and vitamin E, because they’re more stable during food processing and storage (like blanching and freezing). So when hitting the frozen aisle, go for carrots, leafy greens, and broccoli.
Boiling or steaming some veggies (like broccoli and carrots) may actually boost levels of free radical-trapping antioxidants and phytochemicals like carotenoids and polyphenols.
The best bet for getting the most nutritional value out of cooked veggies is to go easy on the temperature and cooking time, and cook with little to no water.
Photo by Caitlin Covington
Originally posted February 2012. Updated March 2013.
What’s your take: fresh or frozen produce? Share your opinions in the comments below or tweet the editor @ksmorin!