Are Frozen Strawberries as Healthy as Fresh?

Strawberries make a great addition to any healthy diet. They are a low calorie fruit, with one cup of sliced strawberries providing only about 50 calories. Fresh strawberries are also an excellent source of vitamin C and flavonoids which have strong antioxidant properties. But are frozen strawberries as nutritious and healthy as fresh strawberries? Read on to learn about the nutritional value and antioxidant activity of fresh vs frozen strawberries.

Nutrient Content

While fresh strawberries contain small amounts of a wide range of vitamins, they stand out as being an exceptionally good source of only one vitamin, namely, vitamin C. An average-sized strawberry provides a whopping 7.1 milligrams of vitamin C, an amount that corresponds to 12 percent of the Daily Value (DV) for this important nutrient. [1]. If stored at room temperature, fresh produce begins to lose vitamin C quickly after being harvested. Storing the produce in the fridge can slow this process, but it cannot stop it. Frozen storage, by contrast, has been shown to be effective at preserving the vitamin C content of fresh produce, but blanching before freezing destroys and leaches out vitamin C.

Unlike many other foods, strawberries are not blanched before freezing. This means that provided they have been frozen at the peak of their freshness, frozen strawberries are an excellent source of vitamin C. In fact, a study published in the Journal of Agricultural and Food Chemistry found that even after three months, frozen strawberries contained virtually as much vitamin C as before freezing [2]. Similar results have been reported by researchers studying the vitamin C content of fresh vs frozen blueberries.

Antioxidant Activity

While certain vitamins, including vitamin C, have antioxidant properties, they are by no means the only compounds that give fresh berries like strawberries their antioxidant properties. Flavonoids, which are classified as secondary plant metabolites, are an example of another type of antioxidant compound, and fresh strawberries are packed with these strong antioxidants. All antioxidants, whether they are classified as nutrients or secondary plant metabolites, have the ability to neutralize free radicals which are hazardous molecules that can cause damage to your body at the cellular level, increasing the risk of age-related diseases and promoting aging in general.

But how do frozen strawberries compare to fresh strawberries in terms of antioxidant activity? To answer this question, let's take a look at a study published in the International Journal of Food Sciences and Nutrition in 2010. This intriguing study compared the in vitro antioxidant activity of fresh vs frozen strawberries, and found that on a dry weight basis, fresh strawberries were significantly better than frozen strawberries in terms of total antioxidant activity (TAA) [3].

References
1. USDA National Nutrient Database for Standard Reference (Release 28, released September 2015, slightly revised May 2016). USDA Database
2. A. Bouzari, D. Holstege and D. Barrett (2015). Vitamin Retention in Eight Fruits and Vegetables: A Comparison of Refrigerated and Frozen Storage. Journal of Agricultural and Food Chemistry, 63, 957-962. PubMed
3. K. Marques et al (2010). Differences in antioxidant levels of fresh, frozen and freeze-dried strawberries and strawberry jam. International Journal of Food Sciences and Nutrition, 61(8):759-69. PubMed