Changes of carotenoid content in carrots after application of pulsed electric field treatments

Abstract

Under certain conditions, pulsed electric fields (PEF) can promote the accumulation of phytochemicals through a stress-mediated response in plant tissues. Likewise, electropermeabilization of cell membranes can also improve the extraction of intracellular compounds. The objective of this study was to evaluate the main causes driving the increase in carotenoids content in PEF-treated carrots and to study the impact of those treatments on their relevant quality attributes. Carrots were treated with PEF differing in electric field strength (E) (0.8, 2 and 3.5 kV/cm) and number of pulses (5, 12 and 30). Individual carotenoids content, colour, pH and total soluble solids (TSS) were determined after 0 h and 24 h after PEF treatment. Total and individual carotenoid contents (phytoene and β-carotene) increased just after applying E ≥ 2 kV/cm, whereas lutein concentration decreased, and that of α-carotene remained similar to that found in untreated carrots. After applying 2 and 3.5 kV/cm, TSS and pH remained unaltered, but cortical browning index increased, which was correlated to carotenoid content. Increase in total carotenoid content is likely related to better extractability, but differences in the content of individual compounds suggest that PEF may also act by modulating their biosynthesis or causing their degradation.

This research has been financed by the Ministerio de Economía y Competitividad (Spain) reference AGL 2013-44851-R. López-Gámez, G. thanks the Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) for the predoctoral grant.