The impact of pulsed electric field treatment on selected bioactive compound content and color of plant tissue

摘要

The aim of this study was to analyze the impact of pulsed electric field treatment on selected bioactive compound content and color of plant tissue. For this purpose apple and carrot tissues were treated by pulsed electric field (PEF) at 0, 1.85, 3, 5 kV/cm and 0, 10, 50 and 100 pulses which corresponded to the specific energy input of 0-80 kJ/kg. The electroporation efficiency was assessed by the means of electrical conductivity (EC) measurement. Immediately and 60 min after the PEF application the optical properties of both materials were measured and compared. Moreover, the total carotenoid content was determined in the case of carrot, whereas in the case of apple the free radical scavenging activity and the total polyphenol content was examined. The highest EC values were observed when 30 and 40 kJ/kg were delivered to the carrot and apple samples, respectively. The total color change (Delta E) of carrot tissue as a result of PEF treatment was smaller (Delta E-0min = 1.64-5.51; Delta E-60min = 133-3.91) than in the case of apple samples (Delta E-0 = 0.48-7.20; Delta E-60 = 1.25-21.87) which could be linked to the different chemical compositions of these raw materials. The application of PEF at 1.85 kV/cm regardless of the applied pulse number increased the total carotenoid content (TCC) up to 11.34%. In turn, the maximal increase of total polyphenolic content (TPC) and antioxidant activity (EC50) in the case of apple tissue was observed for samples treated by 10 pulses at 1.85 kV/cm. The utilization of 3 kV/cm decreased the TCC up to 2533% whereas the application of PEF at 5 kV/cm and 100 pulses decreased the TPC and EC50 up to 35.93 and 32.95%, respectively. The research indicated that PEF can be used to enhance the extractability of bioactive compounds from plant tissue and to modify its color.