A novel protecting method for visual green color in spinach puree treated by high intensity pulsed electric fields Original Research Article

Green vegetables is easily to lose green color during processing and storage. In this paper a novel high intensity pulsed electric field (PEF) technique is applied to process spinach puree with dissoluble zinc salt. Various experimental conditions of the PEF process, such as water-soluble Zn2+ ion concentration (20–200 ppm), electric field strength (20–100 kV/cm) and storing temperature (25 °C and 37 °C), were investigated to optimize the process. Result shows: PEF method can increase the stability of chlorophyll by way of increasing electric fields, adding zinc ion and stabilizers. Spinach puree treated by PEF with acetate zinc below 75 ppm can be stored for a long time at room temperature, and visual green color in spinach puree treated by PEF (25 °C, several nanoseconds) can reach the similar effect of the thermal processing (121 °C, 60 min). From the viewpoints of energy, flavor and vegetable quality and process time, this method is more effective than thermal processing.