Pulsed electric field and mild thermal processing affect the cooking behaviour of carrot tissues (Daucus carota) and the degree of methylesterification of carrot pectin

Abstract

For the first time, the effect of pulsed electric field (PEF) and mild thermal processing on the texture of cortex and vascular carrot tissue during subsequent thermal processing (i.e. cooking behaviour) was compared and the degree of methylesterification (DM) of pectin from the pretreated tissues was investigated. The PEF and mild thermal pretreatment slowed down the cooking behaviour of the carrot tissues, especially when the pretreatments were combined. The DM of pectin from vascular tissue was lowered after both types of pretreatments, the effect being most pronounced in the case of the combination of the PEF and mild thermal pretreatment. In contrast, the DM of cortex pectin only decreased after the mild thermal pretreatment and after the combination pretreatment. This study demonstrates that besides mild thermal pretreatments also PEF pretreatments can be considered in the context of texture preservation of thermally processed fruits and vegetables.

Effect of pulsed electric field and mild thermal processing on texture-related pectin properties to better understand carrot (Daucus carota) texture changes during subsequent cooking

“…Moreover, Moens et al (2020) recently showed that the slower cooking behaviour of PEF treated carrot tissue was correlated with the pectin DM. This indicates that PEF may affect the structure of pectin in the cell wall and middle lamella.…”

“…Recently, pulsed electric field (PEF) technology was also found to slow down the texture degradation of carrot tissue during cooking (i.e. cooking behaviour) (Moens et al, 2020). PEF technology refers to the application of short (µs-ms) intensive electric pulses to biological cell material that is surrounded by a conductive medium and placed between two electrodes.…”

“…cell size) and medium characteristics (e.g. conductivity) determine the treatment efficiency (Ben Ammar et al, 2011;Kanduser & Miklavcic, 2009;Moens et al, 2020;Puértolas et al, 2012;Toepfl et al, 2006;Vorobiev & Lebovka, 2008). This technology is already in use to inactivate micro-organisms in liquid food products (10-15 kV/cm), and to promote diffusion processes in plant tissues (0.7-3 kV/cm), facilitating drying and extraction processes (Pagan & Manas, 2006;Toepfl et al, 2006;Vorobiev & Lebovka, 2008).…”

“…As the cell membranes are no longer intact, the turgor pressure is lost. This results in a softer texture and a lower cutting force of fresh tissue (Botero-Uribe et al, 2017;Leong et al, 2014;Moens et al, 2020).…”

“…This indicates that PEF may affect the structure of pectin in the cell wall and middle lamella. Moens et al (2020) hypothesised that the PEF pretreatment facilitates the enzymatic demethylesterification of pectin by PME: as the membranes are permeabilised by PEF, intracellular cations may migrate to the cell wall and middle lamella, promoting PME activity.…”