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Anisotropic swelling of cell walls of sugar beet tissue: Influence of ion‐exchange and sucrose
Author(s) -
Gieringer Rita,
Steinert Peter,
Buttersack Christoph,
Buchholz Klaus
Publication year - 1995
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.2740680407
Subject(s) - swelling , cell wall , sugar beet , sucrose , chemistry , middle lamella , transmission electron microscopy , ion , sugar , membrane , biophysics , analytical chemistry (journal) , nuclear chemistry , biochemistry , materials science , chromatography , biology , nanotechnology , organic chemistry , horticulture , composite material
Cell walls of sugar beet tissue ( Beta vulgaris var altissima Döll), the cell and vacuolar membrane of which were destroyed by heat or the action of lipophilic substances, were observed by transmission electron microscopy. The average thickness of secondary walls (SW) and the region composed of the middle lamella and two primary walls (PW) was statistically evaluated and compared with the swelling of the entire denaturated tissue. By introducing different counter‐ions with water as solvent, the extension along the wall E 2 increased in the order H + < K + ∼ Ca 2+ < La 3+ , and the extension across the wall (SW plus PW) E 2 increased in the order Ca 2+ ∼ K + < La 3+ < H + . Replacement of the swelling medium by sucrose solution (0.5 M ) caused either an increase of the wall thickness (K + , Ca 2+ , La 3+ ) or a contraction (H‐form); the anisotropy E 2 E 3 was either negative (H + , Ca 2+ , La 3+ ) or positive (K + ). Comparison of the PW with the SW region mostly yielded a ratio of E zpw/ E zxm between 1 and 2. The ion‐exchange K + →Ca 2+ was predominantly manifested in a change of the PW region, while the influence of sucrose on the K + ‐treated wall seemed to be confined to the SW region. Specimens in the H‐form in water showed a further increase of the wall thickness (SW and PW) when the pH was reduced from 7 to 3. (At pH 3 the carboxyl groups inside the wall must exist nearly completely in the non‐dissociated state.) All the changes of swelling observed may be explained by a superposition of electrostatic and anisotropic hydrophobic interactions between the matrix polysaccharides.