Fresh vs Frozen Blueberries: Which Are Healthier?
Whether cultivated or wild, fresh blueberries are a tasty, versatile ingredient, and they are good for you, too. But the season for blueberries is short, which means you may have to look beyond the fresh kind if you want to whip up a healthy blueberry smoothie (such as this blueberry and kale smoothie) or make a batch of healthy blueberry muffins (such as these grain-free blueberry muffins). The good news is that frozen blueberries are readily available year round, and they can be used as a substitute for fresh blueberries in everything from smoothies and muffins to fruit salads and pies. But how do frozen blueberries compare to fresh blueberries in terms of nutritional value and potential health benefits? To find out all about the antioxidant properties and nutrient content of fresh vs frozen blueberries, keep reading.
Antioxidant Properties
Antioxidants are thought to have all sorts of health benefits, including slowing down aging in general and providing protection against the development and progression of degenerative conditions like cardiovascular disease, osteoporosis and neurodegenerative diseases [1]. Antioxidants have also been researched for their ability to provide benefits for people with certain autoimmune diseases such as psoriasis (see Antioxidants and Psoriasis). The high levels of antioxidants in blueberries make them a superfood that may help protect you from developing health problems like those listed above, but do frozen blueberries provide the same level of protection as their fresh counterparts?
A study published in the Journal of Biomedicine and Biotechnology found that not only fresh but also frozen blueberries are loaded with anthocyanins, the flavonoid pigments that give fresh blueberries their strong antioxidant properties. In fact, this study found no significant differences in the in vitro antioxidant capacity of anthocyanin extracts derived from fresh vs frozen blueberries. [2]
Nutrition Facts
While fresh blueberries contain small amounts of a wide range of vitamins and minerals, they stand out as being an exceptionally good source two micronutrients: vitamin C and vitamin K. A 100-gram serving of fresh blueberries provides 9.7 milligrams of vitamin C, which corresponds to 16 percent of the Daily Value (DV) for this vital nutrient, and 19.3 milligrams of vitamin K, which is equivalent to 24 percent of the DV for vitamin K [3].
In fresh produce, vitamin C begins to degrade quickly after harvest if the produce is stored at room temperature. Refrigeration slows this process but does not stop it. Frozen storage, by contrast, has been shown to be effective at preserving the vitamin C content of fresh produce, but blanching produce before freezing often causes significant degradation, plus some of the vitamin C leaches into the blanching water. Unlike many other foods, blueberries are not blanched before freezing, which means blueberries that are frozen immediately after harvest are an excellent source of vitamin C. In fact, a study published in the Journal of Agricultural and Food Chemistry found that blueberries that were stored in the freezer had significantly higher levels of vitamin C than blueberries that were stored in the fridge for the same amount of time. [4]
Also vitamin K, which plays an important role in helping blood clot and keeping your bones healthy, is protected when fresh produce is stored in the freezer, so you can expect blueberries frozen at the peak of their freshness to be a good source of vitamin K, just like fresh blueberries [3, 5].
References
1. K. Pandey and S. Rizvi (2009). Plant polyphenols as dietary antioxidants in human health and disease. Oxidative Medicine and Cellular Longevity, 2(5): 270-278. PubMed
2. V. Lohachoompol, G. Srzednicki and John Craske (2004). The change of total anthocyanins in blueberries and their antioxidant effect after drying and freezing. Journal of Biomedicine and Biotechnology, 2004(5), 248-252. PubMed
3. USDA National Nutrient Database for Standard Reference (Release 28, released September 2015, slightly revised May 2016). USDA Database
4. 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
5. A. Hoisington. Does freezing kill vitamin K? Oregon State University Extension Service. Website
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