Observations on the water distribution and extractable sugar content in carrot slices after pulsed electric field treatment

Abstract

The impact of pulsed electric field (PEF) processing conditions on the distribution of water in carrot tissue and extractability of soluble sugars from carrot slices was studied. Time domain NMR relaxometry was used to investigate the water proton mobility in PEF-treated carrot samples. Three distinct transverse relaxation peaks were observed in untreated carrots. After PEF treatment only two slightly-overlapping peaks were found; these were attributed to water present in the cytoplasm and vacuole of carrot xylem and phloem tissues. This post-treatment observation indicated an increase in water permeability of tissues and/or a loss of integrity in the tonoplast. In general, the stronger the electric field applied, the lower the area representing transverse relaxation (T2) values irrespective of treatment duration. Moreover an increase in sucrose, J3-and a-glucose and fructose concentrations of carrot slice extracts after PEF treatment suggested increased both cell wall and vacuole permeability as a result of exposure to pulsed electric fields.

Effect of pulsed electric fields on carotenoid and phenolic bioaccessibility and their relationship with carrot structure

“…Additionally, changes in cell walls could also cause differences in the water absorbed into the polysaccharides network which affect other textural and sensory perception properties. [49] Electropermeabilisation and cytoplasmic content leakage could also increase adhesiveness of PEF-treated carrots since Aguiló-Aguayo et al [50] reported that cellular content moved from vacuoles to cytoplasm and outside the cell. Therefore, release of this intracellular juice rich in sugars may cause the higher adhesion to the texture analyser probe.…”

Effect of pulsed electric field treatment on water distribution of freeze-dried apple tissue evaluated with DSC and TD-NMR techniques

“…Recently TD-NMR has been employed to investigate the cell walls and membrane disruption and water mobility in the plant tissue subjected to PEF treatment (Ersus, Oztop, McCarthy, & Barrett, 2010;Aguiló-Aguayo, Downey, Keenana, Lyng, Brunton, & Rai, 2014). Ersus et al (2010) were able to follow the changes of T 2 relaxation times from two different cell compartments namely cytoplasm and vacuoles.…”

Time-Domain Nuclear Magnetic Resonance Investigation of Water Dynamics in Different Ginger Cultivars

“…Consequently, different transverse relaxation time T 2 components represented water in different mobile states in ginger samples rich in water (approximately 90%, Table 1), and longer T 2 relaxation times indicated more mobile water. In a low-field NMR study of carrot tissue, 37 three T 2 components, T 2a (10.3 ms), T 2b (54.2 ms), and T 2c (318 ms), were observed and assigned as water under three different combination states to distinguish the different degrees of tightness, i.e., water bound to rigid components of cell walls, water in extra-cellular compartments or cytosol and water in vacuoles, respectively. In our present study, the assignment of relaxation time T 2 components was more complicated for Henan gingers, which exhibited significantly different T 2 components than those of the other four ginger cultivars.…”