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Keywords:

  • Carrot juice;
  • colouring pigments;
  • enzymes;
  • high hydrostatic pressure;
  • micro-organisms;
  • ultrasound

Summary

The combined effects of ultrasound (US) and high hydrostatic pressure (HHP) on enzymes, micro-organisms, colouring pigments, total polyphenols, ascorbic acid and physicochemical properties of carrot juice were investigated. Carrot juice was treated with sonication (20 kHz, 70% amplitude) and HHP (250, 350, 450 MPa) at room temperature for 10 min. For comparison, fresh carrots were water blanched (WB) at 100 °C for 4 min and carrot juice was then extracted. As results, highest improvements in colouring pigments were observed in WB and US-HHP450 treatments, which also completely inactivated micro-organisms. The highest reduction in enzymes was observed in WB treatment followed by US-HHP450. Total polyphenol contents increased significantly in US, HHP and US-HHP treatments with the highest increase in US-HHP450, but it decreased significantly in WB treatment. Ascorbic acid contents significantly decreased in WB and HHP450, while increased in US and US-HHP treatments. Results indicate that US-HHP450 treatment improves the quality of carrot juice and serves as a good alternative for blanching treatment.