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Effect of osmotic stress on microstructure and mass transfer in onion and strawberry tissue
Author(s) -
Ferrando Montserrat,
Spiess WEL
Publication year - 2003
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.1429
Subject(s) - epidermis (zoology) , osmotic shock , osmotic dehydration , biophysics , thermal diffusivity , membrane , osmotic pressure , shrinkage , permeation , permeability (electromagnetism) , chemistry , mass transfer , chromatography , biochemistry , materials science , biology , anatomy , composite material , physics , quantum mechanics , gene
Abstract We investigated the structural changes in onion epidermis and strawberry cortex tissue due to osmotic stress during osmotic treatment (OT) with sucrose solutions of concentrations ranging from 300 to 600 g kg −1 . We used miniaturised experiments with confocal scanning laser microscopy (CSLM) to monitor microstructural changes—cellular shrinkage and viability—during OT. The overall cellular shrinkage of these plant tissues was not significantly different under the same conditions of osmotic stress. For onion epidermis we determined the transmembrane water flux from the cellular shrinkage and found that the coefficient of water membrane permeability was (1.0 ± 0.39) × 10 −6 mol 2 J −1 m −2 s −1 . Osmotic stress did not affect the cellular viability of onion epidermis but significantly reduced the viability of protoplasts of strawberry in the whole range of solution concentrations. We used Fick's unsteady state second‐order diffusion equation to describe cellular water transport under transient conditions. The pseudo‐diffusional approximation led to water diffusivity values in the range (3–10) × 10 −12 m 2 s −1 for both onion epidermis and strawberry cortex tissue. The concentration of the solution did not significantly affect the values of effective water diffusivity, which indicated the primary role of the plasma membrane during the initial stages of OT. Copyright © 2003 Society of Chemical Industry