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Shear stiffness and density in potato parenchyma
Author(s) -
Scanlon Martin G.,
Day Andrea J.,
Povey Malcolm J. W.
Publication year - 1998
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1046/j.1365-2621.1998.00193.x
Subject(s) - turgor pressure , stiffness , shear (geology) , rheometer , chemistry , materials science , composite material , rheology , biophysics , biology
To understand textural changes that occur during processing of potatoes, a more comprehensive understanding of the mechanical properties of potato tubers is desirable. Specimens of potato parenchyma had their turgor osmotically adjusted to be either fully turgid or flaccid. Control specimens at normal turgor were also studied. Density of the specimens was measured using Archimedes' principle. The storage ( G′ ) and loss ( G″ ) moduli of the complex shear stiffness were measured in a rheometer. A weak positive relationship between G′ and density was apparent, but only for the osmotically adjusted specimens. This was true regardless of whether specimens were fully turgid or flaccid. However, no such relationship was observed for the control (normal turgor) specimens, which was probably due to slight variation in turgor pressure affecting G′ independently of the effect of density on G′ , and so masking the effect of density on shear stiffness. A positive relationship between G″ and density was observed, but only for flaccid specimens. This relationship was putatively assigned to shear strain energy dissipation by starch granule movement in a viscous protoplasm.