Impact of critical high‐intensity pulsed electric field processing parameters on oxidative enzymes and color of broccoli juice

Abstract

This research evaluated the influence of high-intensity pulsed electric field (HIPEF) processing parameters, electric field strength, treatment time, and polarity on color difference (∆E*), polyphenol oxidase (PPO), and lipoxygenase (LOX) activities in broccoli juice. An optimization of HIPEF processing was accomplished and compared with thermal treatment (90°C/60 s). The lowest RALOX (68.71%) and RAPPO (36.11%) were reached at the strongest HIPEF conditions (35 kV/cm for 2,000 µs in bipolar mode). Bipolar mode pulses showed lower RALOX and RAPPO than monopolar mode. However, polarity did not show a significant effect on ∆E*. LOX was always more resistant to HIPEF treatment than PPO. The optimization process (26.35 kV/cm for 1,235 μs in bipolar mode) showed around 60% of enzyme inactivation and ∆E* = 0.69. Thermally processed broccoli juice exhibited the greatest color difference (∆E* = 7.89). HIPEF processing could be an appropriate technology to preserve the color properties and reduce the enzyme activity of broccoli juice. Practical applications Vegetable juices, in particular broccoli juice is attracting the food industry attention because it contains high amounts of nutrients; however, this fact increase their susceptibility to endogenous enzymes. HIPEF is a nonthermal technology for liquid food preservation that inactivates microorganisms and enzymes without compromising the nutritional and sensorial features of foods. Consequently, this technology could be used in the food industry as an alternative for thermal treatment to inactivate deteriorative enzymes in vegetable juices, offering to consumers a high quality product.