Freezing Blueberries Boosts Nutritional Value, Says Study

Blueberry fields forever!

According to results from a study conducted recently at South Dakota State University, frozen blueberries are healthier for consumers than their non-frozen counterparts – even after months in cold storage or the home freezer.

“The ice crystals that form during freezing disrupt the structure of the plant tissue, making the anthocyanins [a group of antioxidant compounds] more available,” concluded Marin Plumb, the graduate student who tracked antioxidant levels in blueberries over periods of one, three and five months in a controlled experiment on campus.

Anthocyanins produce the pigment in blueberries. Since most of the color is in the skin, freezing the berries improves the availability of antioxidants through preservation, explained Plumb, who has a degree in food science.

In other words, naturally occurring leaching during the freezing process increases the concentration of powerful antioxidants. Anthocyanins are associated with the prevention macular degeneration, the leading cause of blindness in people over age 65. They are also believed to promote increased memory, concentration and coordination.

Blueberries-Marin-Plumb-SDSUFreezing blueberries results in greater concentration of the fruit’s powerful antioxidants, according to research conducted by South Dakota State University graduate student Marin Plumb.“Blueberries go head to head with strawberries and pomengranates in antioxidant capacity,” said Basil Dalaly, Plumb’s research adviser, who noted that the fruit is second only to strawberries in popularity among berry consumers in the United States. The professor teaches a class on phytochemicals, the naturally occurring chemical compounds in fruits and vegetables, many of which have the potential to boost the immune system and impact life threatening diseases such as including cancer and cardiovascular ailments.

Antioxidants, such as anthocyanins, eliminate free radicals, which are produced through common biological reactions within the human body and through outside factors such as the sun, pesticides and other pollutants, explained Dalaly.

If unchecked, he added, these free radicals can attack DNA, proteins and lipids, resulting in cellular changes that lead to development of potentially deadly diseases such as cancer.

"That is why we need to consume at least seven to nine servings of fruits and vegetables a day,” said Dalaly. "The greener or redder, the better.”

Meanwhile, the Wild Blueberry Association of North America (WBANA) points out that epicatechiun, an antioxidant found in abundance in wild blueberries, guards against urinary tract infections.

But that’s not all. Pterostibene in blueberries is believed to reduce the build up of so-called “bad” cholesterol that can lead to heart disease and stroke. Then there are antioxidant compounds such as pectin and ellagic acid, both of which may help prevent cancer. And tannins are said to reduce inflammation in the digestive system.