Storing Temperatures for Freeze-Dried Blueberry Powder

By Robby Gardner, Associate Editor

Temperature conditions can influence nutrient levels in wild blueberry (Vaccinium angustifolium). One of the fruit’s most highly regarded nutrients is anthocyanin, a compound that offers blue pigment and potential health benefits. Frozen storage of wild blueberry appears to increase its anthocyanins, but the effect of dry storage temperatures on wild blueberry is unexplored-until now. Data published in the Journal of Agricultural and Food Chemistry offers a first look at the effect of dry storage temperatures on wild blueberry anthocyanins.

Researchers from the University of Milan and the University of Maine stored freeze-dried wild blueberry powder at -80 °C before moving it into 60 individual vacuum-sealed sample bags stored at 25, 42, 60, or 80 °C for 49 days. Anthocyanin degradation was measured.

Degradation appeared slow at relative room temperatures (14 and 25 °C), with only 3% loss of anthocyanins by day 14. On the contrary, storage at 60 and 80 °C resulted in fast losses of 60–85% total anthocyanins in just 3 days. A direct correlation between reaction rate and temperature confirmed the effect of temperature on anthocyanin decay.

Rising temperatures negatively impacted total antioxidant activity, too, but the loss was not directly correlated with anthocyanin loss.

Freeze-dried wild blueberry powder is a common format for including wild blueberry in jams, juices, dairy products, baked goods, and numerous other products. Such information regarding its shelf life should benefit both manufacturers of wild blueberry products and researchers who need to store the ingredient before testing it on animals and humans.

Freeze-dried wild blueberry powder was provided by FutureCeuticals Co. (Momence, IL) and the Wild Blueberry Association of North America.