Study of pulsed electric field treated citrus juices

Abstract 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°, 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 °C. The pH, Brix°, 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. Industrial relevance Pasteurization of fruit juices by pulsed electric fields (PEF) has received considerable attention during the last years and will most likely be the first industrial application of PEF. Consequently, for legal approval of such a process, an indepth product characterisation of treated product is required. This paper found limited differences in key quality characteristics between untreated and PEF treated citrus juices. However, in agreement with the authors, more work regarding the mechanisms of changes during PEF treatment and during subsequent storage are required.