Study of pulsed electric field treated citrus juices

The effect of pulsed electric field (PEF) treatment, applied in a continuous system, on physical and chemical properties of freshly squeezed citrus juices (grapefruit, lemon, orange, tangerine) was studied. The aim of the present work was to investigate the effect of PEF technology on pH, Brix degrees, electric conductivity, viscosity, nonenzymatic browning index (NEBI), hydroxymethylfurfurol (HMF), color, organic acid content, and volatile flavour compounds of citrus juices. The juices were treated by 50 pulses at 28 kV/cm. The treatment temperature was less than 34 degrees C. The pH, Brix degrees, electric conductivity, viscosity, NEBI and HMF of citrus juices practically did not change. At most of samples there was no or slightly visible difference in the color. In all cases the absorbance spectra of treated and untreated samples were similar to each other. There was no significant change in organic acid content of juices. The volatile flavour compounds of treated juices are essentially equal to those present in unprocessed juice as shown by SPME GC-MS results. (c) 2005 Elsevier Ltd. All rights reserved.