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Keywords:

  • antioxidant capacity;
  • ORAC;
  • pH;
  • blueberry;
  • Vaccinium angustifolium

ABSTRACT:

Temperature, pH, and oxygenation of extracted blueberries were examined to determine how processing may affect the antioxidant capacity of blueberry food products. Extraction of fruit at 60 °C resulted in higher recovery of anthocyanins and antioxidant capacity, compared to extracts obtained at 25 °C. Subsequent room temperature storage resulted in losses in anthocyanins and antioxidant capacity only in those extracts obtained at 60 °C. Antioxidant capacity was greatest in pH 1 extracts, compared to extracts at pH 4 and 7. Oxygenation was detrimental to both anthocyanins and antioxidant capacity. Antioxidant capacity of processed products was positively correlated with anthocyanin (R = 0.92) and phenolic content (R = 0.95), and negatively correlated with % polymeric color (R = -0.64). In general, products that had experienced less processing had a higher antioxidant capacity. Simple colorimetric tests for anthocyanins and phenolics proved to be useful indicators of antioxidant capacity in processed products.