Radiant Zone Dryer Preserves Antioxidants in Dried Blueberry Powder

DALLESPORT, Wash. – An innovative technology developed by Columbia PhytoTechnology and Washington State University assistant professor of food science, Kerry Ringer, preserves health-promoting compounds in dried blueberry powder. The technology meets consumer demands for highly nutritious foods at the same time as addressing industry concerns about costs.

Washington State University assistant professor of food science Kerry Ringer. Click image for high resolution. Photo: Brian Charles Clark, Washington State University

Called the Radiant Zone Dryer, the technology was the subject of a study published recently in the Journal of Agricultural and Food Chemistry. The study shows that its dried blueberry products retain as many antioxidants and anthocyanins as liquid products.

“We focused our study on drying of blueberry puree, blueberry juice and blueberry extract supplied by Washington fruit processing companies,” said Ringer.

It’s well known that blueberries are health promoting. Rich in antioxidants and anthocyanins, consumption of blueberries is associated with improvement of ischemic stroke outcomes and antioxidant capacity in blood plasma after eating them. (In ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction of the brain tissue in that area.) In pigs, reduced levels of plasma lipids have been found in association with blueberry consumption while rodents have been found to overcome the genetic predisposition to Alzheimer’s disease.

In comparison to most other berries, blueberries have higher antioxidant activity and anthocyanin content. Anthocyanins are the compounds that, among other things, give wine their colors. Like antioxidants, anthocyanins are associated with health-promoting effects. Consequently, there is a large consumer demand for fresh blueberries as well as their products.

Blueberries, though, are a seasonal crop with a short shelf life as a fresh product. To meet consumer demand, fresh berries have to be either frozen or otherwise processed. Because maintaining frozen products may be cost prohibitive, there is a growing interest in developing cost-effective preservation methods capable of minimizing the degradation of anthocyanins in processed berry products such as powders.

Columbia Phytotech’s technology customizes drying times and temperatures to get the best product at a reasonable cost. By using damaged or bruised fruit, the technology recovers profit from the loss columns of producers’ and processors’ books. Located in rural Dallesport, Wash., Columbia hopes to play a role in the economic development of the area by dovetailing technology jobs into the area’s rural economy.

“This project demonstrated the development of value-added products that potentially bolster profit margins and the types and numbers of jobs in agriculture, Washington’s No. 1 industry,” Ringer said. “The Radiant Zone Dryer technology also provides options to ag producers for processing waste.”

“Effect of the Novel Radiant Zone Drying Method on Anthocyanins and Phenolics of Three Blueberry Liquids” by Moumita Chakraborty, Mark Savarese, Eileen Harbertson, James Harbertson, and Kerry L. Ringer was published in the Dec. 2 issue of the Journal of Agricultural and Food Chemistry and is available online to subscribing institutions by visiting: http://bit.ly/5N06aC.