Ascorbic acid stability during refrigerated storage of orange–carrot juice treated by high pulsed electric field and comparison with pasteurized juice

Abstract

The degradation kinetics of ascorbic acid was determined in orange–carrot juice treated by PEF in order to establish its shelf life. Different electric field intensities (25, 30, 35, and 40 kV/cm) and different treatment times (from 30 to 340 μs) were studied. The ascorbic acid degradation rate ( k) obtained was −0.009 ± 0.0008 μs −1, −0.0140 ± 0.0009 μs −1, −0.0220 ± 0.0023 μs −1 and −0.0187 ± 0.0049 μs −1 for fields of 25, 30, 35, and 40 kV/cm, respectively. The treatment selected was 25 kV/cm. The shelf life of the orange–carrot juice treated by pulses at 25 kV/cm for two times (280 μs and 330 μs) was compared with a heat-treated juice (98 °C, 21 s) kept in refrigerated storage at 2 and 10 °C. The remaining concentration of ascorbic acid in the pasteurized orange–carrot juice was 83%, whereas in the PEF-treated juice it was 90%. The ascorbic acid degradation rate in the juice stored at 2 °C was less than in the juice stored at 10 °C, and in the pasteurized juice it was greater. PEF treatment at 25 kV/cm for 280–330 μs extended the half-life of the juice stored at 2 °C to 50 days.