More efficient dryer maintains antioxidant level of blueberries
By MATTHEW WEAVER
Use of a new drying method may enable berry processors to preserve nutritional value typically lost when the fruit is heated.
Researchers at Washington State University and Columbia PhytoTechnology developed the radiant zone dryer to dry purees or slurries into powders used for packaged and prepared foods and nutritional supplements. Compared to the standard freeze-drying process, preservation of antioxidants was found to be greater in cold blueberries, blueberry extract and blueberry concentrate using the radiant zone dryer.
"We dried them on the radiant zone dryer and found no losses on drying of the antioxidant compound," said Kerry Ringer, assistant professor of food science at Washington State University in Prosser, Wash., and a co-owner in Columbia PhytoTechnology, based in Dallesport, Wash.
Freeze drying is the highest-quality drying technology thus far, Ringer said. Other drying methods can destroy nutrients or require additives, which can dilute the nutritional content.
"For the food industry and consumers in general, they're getting a product that has the antioxidants preserved," she said. "It's like eating fresh blueberries, but they don't have to be fresh blueberries."
Eric Johnson, research and product development manager of Milne Fruit Products, based in Prosser, said the radiant zone dryer differs from ordinary methods in that it uses far less heat, causes less damage and is more efficient. Infrared heating elements move across a belt, onto which purees are placed, he said.
Other methods are very hot and cause the fruit materials to get stuck or become lost, Johnson said.
Johnson has been working with Ringer and the PhytoTechnology researchers to develop a line of products that retain the nutritional quality, flavor, appearance and color of different fruits.
Ringer believes processors and producers will feel the implications of the new method.
The new dryer may open the door to more uses for damaged or overproduced fruit, she said, pointing to a recent excess of blueberries on the fresh market.
Similar results have been found on strawberry purees, Ringer said, and vitamin C was preserved.
Further research will include cranberries, blackberries, raspberries and grapes.
Johnson foresees the method taking off, especially for specialty crops and products focusing on nutrition.
He points to increased efforts in the last two decades to work on micronutrients other than the typical vitamins and materials, even though those are retained by the radiant zone dryer.
"The colors in plants, even though they're not listed now as nutritional elements, they do seem to have an effect," he said. "Entirely what's going on isn't absolutely known for certain, but the science seems to be pointed toward different ways in which these compounds will help human health."
Columbia PhytoTechnology: www.columbiaphytotechnology.com