Effects of Pulsed Electric Fields on Vacuum Drying and Quality Characteristics of Dried Carrot

Abstract

This study investigates the effect of pulsed electric fields (PEF) on the kinetics of vacuum drying (VD) of carrot and on the preservation of the quality of dried carrot tissue. The impacts of PEF-treatment and VD on β-carotene content and color of carrot samples were studied. PEF treatment was applied with intensity E = 0.6 kV/cm and total treatment time tPEF = 0.1 s to reach a high level of carrot tissue electroporation. The VD was applied at the pressure p = 0.3 bar for different temperatures, Td = 25, 50, 75, and 90 °C. The spectrophotometric method was used to determine the β-carotene content. The color was measured using the CIE L* a* b* method. Obtained results indicated that PEF treatment let to a noticeable decrease of drying time (by 33–55% at Td = 25–90 °C). The activation energy was found to be 18.25 kJ/mol and 13.4 kJ/mol for untreated and PEF-pretreated samples, respectively. The reduction of drying time by PEF pretreatment was beneficial for the retention of β-carotene in dried samples. The application of PEF treatment resulted in smaller changes in color ∆E as compared with untreated samples; this tendency was observed for all studied temperatures.