|Authors: ||C.M. Mainland, J.W. Tucker|
|Keywords: ||ORAC (oxygen radical absorbance capacity), antioxidants, anthocyanins, phenolics, highbush blueberry (Vaccinium corymbosun), rabbiteye blueberry (V. ashei), muscadine grape (Vitis rotundifolia)|
Blueberries have recently become recognized as one of the foremost health foods.
A 1996 research report from the United States Department of Agriculture, Human Nutrition Research Center on Ageing, at Tufts University, found blueberries to be the highest in antioxidant activity of the 41 fruits and vegetables tested.
These workers had previously developed an analytical procedure referred to as ORAC (oxygen radical absorbance capacity) for measuring total antioxidant capacity.
The analytical measurement of high antioxidant activity in blueberry fruit was proven to be associated with biological benefits in animal feeding studies.
Blueberries delayed and even reversed some symptoms of ageing in rats.
The reversals in ageing were unprecedented in ageing research.
Our research involved measuring ORAC, phenolics and anthocyanins in blueberry products.
The effect of fruit maturity at the time of harvest affected antioxidant activity differently depending on the type of blueberry.
The rabbiteye cultivars Tifblue and Powderblue had ORAC, anthocyanin and phenolic levels that continued to increase beyond the normal stage for commercial harvest.
Levels in the highbush cultivars Croatan, Reveille and Bladen did not continue to increase after the normal stage of maturity for commercial harvest.
The skins of the blueberry cultivars ‘Reveille’ and ‘Bladen’ contained the major portion of the ORAC activity.
The levels in the skin samples were more than four times the levels in samples from the entire berry.
Levels in the seed samples were less than half the levels found in the skin samples.
Blueberry seeds were much lower in ORAC and phenolic levels per gram than grape seeds.
The ORAC levels remained high after commercial drying.
The ORAC level in ‘Rubel’ and ‘Little Giant’, the highest dried cultivars, was more than 50 per cent higher than levels reported in prunes.
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