Watermelon juice was subjected to high-intensity pulsed electric fields (HIPEF). The effects of process
parameters including electric field strength (30–35 kV/cm), pulse frequency (50–250 Hz), treatment time
(50–2050 ls), pulse width (1–7 ls) and pulse polarity (monopolar/bipolar) on lycopene, vitamin C and
antioxidant capacity were studied using a response surface methodology. Lycopene content was measured
spectrophotometrically, vitamin C was determined by HPLC and antioxidant capacity through
the inhibition of DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. Watermelon juice exhibited high retention
of lycopene and antioxidant capacity when high electric field strengths, frequencies and pulse widths
were applied. However, severe HIPEF treatments reduced vitamin C content. Maximal relative lycopene
content (113%), vitamin C (72%) and antioxidant capacity retention (100%) were obtained when HIPEF
treatments were set up at 35 kV/cm for 50 ls using 7 ls bipolar pulses at 200 Hz.