COLUMBUS, Ohio - Red raspberry cultivars have been found to contain varying levels of nutrient components and antioxidants, opening the doors to grow and market fruits that pack the healthiest punch.
Ohio State University evaluations of two summer cultivars (Lauren and Killarney) and two fall cultivars (Heritage and Caroline) showed varying measurements of dietary fiber, beta-carotene, vitamins A, E and C, and folic acid. Researchers, nutritionists and dietitians have speculated that the combination of such nutrient components produces greater health benefits than each one alone.
"We are finding some excellent results with berries and we are slowly realizing they can be a part of the diet with people with specific health needs," said Dick Funt, an Ohio State small fruit specialist. "If a person, say, needs more vitamin A or vitamin E, berries with high levels of these vitamins can be a part of their diet and it's a more organic way of staying healthy, rather than taking supplements."
Funt and his associates measured the components of freeze-dried raspberries, speculating that the highest nutrient levels could be immediately preserved as soon as the berries were picked from the plant. For example, in comparison to the U.S. Department of Agriculture Nutrient Database, freeze-dried raspberries contained four to 10 times as much dietary fiber as raw raspberries or any other raw fruit, such as apples, pears and plums.
In comparing cultivars, Caroline generally was 20-44 percent higher in beta carotene, 27-43 percent higher in vitamin A, 16-77 percent higher in vitamin E and 25-48 percent higher in vitamin C than the other raspberry cultivars tested.
Researchers also compared the Oxygen Radical Absorbency Capacity (ORAC) levels among the four cultivars. ORAC is a system of measuring the level of antioxidants (cancer-fighting agents) in food and is being recognized by scientists and nutritionists as the main method for determining overall antioxidant potential. The higher the ORAC number the greater number of antioxidants present.
National research has suggested that the consumption of fruits and vegetables with a high ORAC (1,600 to 5,000 ORAC units per 100 grams or 3.5 ounces) may slow the aging process in both the body and the brain and has a significant impact on plasma and tissue antioxidant capacity.
In preliminary Ohio State studies, the Caroline cultivar had 47 percent more ORAC units than Lauren or Killarney and 65 percent more ORAC units than the average of two Heritage fall red raspberry samples. The Caroline cultivar contains 2,130 ORAC units/100 g. By comparison, blueberries contain 2,400 ORAC units and strawberries contain 1,540 ORAC units. Research suggests that consuming 10 grams of freeze-dried Caroline red raspberries may provide 40-66 percent of the 3,000-5,000 recommended daily ORAC units.
Funt emphasized that the nutrient levels in the berries may vary from season to season, region to region and among soil types and levels of soil fertility. Harvest procedures also have an impact on the level of such components. "Growers need to understand these factors when going to the market with their product," said Funt. "Further studies need to be done that explain how these factors may effect nutrient components in different raspberry varieties."