Impedance Parameter Characterizing Apple Bruise

Abstract

The electrical impedance spectra of Jonathan apples exposed to different pressing force were measured in the frequency range from 1 kHz to 1 MHz with an HP 4284A precision RLC meter. The apoplasmic resistance (Ra), the symplasmic resistance (Rs), and the Ra/Rs ratio were determined as a function of the force and the deformation. Below the bioyield deformation, there was no observable change in the value of Ra/Rs. Above the bioyield, the Ra/Rs ratio markedly decreased in consequence of the Ra decrease due to both the increased ion concentration in the apoplasmic part and the decrease of cell membrane resistance as a result of cell membrane rupture.

Cadmium- and Flood-Induced Anoxia Stress in Pea Roots Measured by Electrical Impedance

“…Water gets into plant roots mainly via the apoplasmic route, but it can also enter cells through aquaporins -cell membrane protein channels that allow the faster passage of water (Martinoia et al, 2000). The latter mechanism allows to increase the amount of water rapidly in fl ooded pea root tissues and this in turn increases tghe ion mobility, which is one of the main factors affecting plant tissue impedance (Vozáry et al, 1999). Moreover, the natural growth phenomena of pea seedlings lead to the formation of tracheae, which may be considered as electrical conductors, and an increase in their diameter.…”

“…Tissue impedance is closely related to both cellular ionic mobility (Vozáry et al, 1999) and the diameter of electrical conductors. The changes in these two factors will also lead to a decrease of Table I The magnesium treatment did not cause any difference in the impedance parameters.…”

“…A linear correlation was found between intracellular resistance and frost hardening capability of Scots pine (Pinus sylvestris L.) (Repo et al, 2000). Prediction of mechanical destruction (Vozáry et al, 1999), drying of apple slices (Mészáros et al, 2005), and germinability of soybean and snap bean seed are also possible with EIS (Vozáry et al, 2007). The magnitude of environmental stress factors originating from climatic changes or from polluting agents has increased, of which heavy metal stress is among the most harmful ones (Tuba and Csintalan, 1992).…”

“…where j = √-1 , ω = 2πf, Cm is the cell membrane capacitance, and ψ is a constant phase angle (Vozáry et al, 1999).…”

“…The resistance and the capacitance of different cellular structures are represented by the elements of linear equivalent circuits (Hayden et al, 1968;Zhang and Willison, 1991;Privé and Zhang, 1996). Different models have been created in order to approximate cellular compartments: the Hayden model, in which the apoplasmic (Ra) and the symplasmic (Rs) resistance are calculated (Hayden et al, 1968); the modifi ed Hayden model also considers the cell membrane capacitance (Vozáry et al, 1999); and the "double shell model" includes the interior resistance of vacuoles and the plasma membrane capacitance as well (Zhang and Willison, 1991).…”