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Keywords:

  • orange juice;
  • high pressure;
  • carotenoids;
  • radical-scavenging capacity;
  • vitamin A

Abstract

Effects of high-pressure treatment on the orange juice carotenoids (β-carotene, α-carotene, zeaxanthin, lutein and β-cryptoxanthin) associated with nutritional (vitamin A) and health-related (radical-scavenging capacity) values were investigated. Various high-pressure treatments (50–350 MPa) combined with different temperatures (30 and 60 °C) and times (2.5, 5 and 15 min) of treatment were assayed. The carotenoid content of the orange juice was analysed by HPLC-UV, the vitamin A value was determined as retinol equivalents (RE) and the free radical-scavenging capacity was evaluated using the DPPH (2,2-diphenyl-1,1-picrylhydrazyl) radical model system. A storage study was carried out at refrigeration temperature (4 °C). High-pressure treatments at 350 MPa produced significant increases of 20–43% in the carotenoid content of fresh orange juice (from 3.99 to 4.78–5.70 mg l−1). A non-uniform behaviour of high-pressure treatments was detected. An increase in time (beyond 5 min) or temperature (above 30 °C) of treatment did not improve the amount of carotenoids extracted. Owing to better extraction of carotenoids, an increase in vitamin A value from 164 to 238 RE l−1 (45%) was achieved with the 350 MPa/30 °C/5 min treatment. No correlation was found between the increase in carotenoid amount extracted and the free radical-scavenging activity.

© 2002 Society of Chemical Industry