Food Structure


The ultrastructure of pea and fababean spun proteins has been studied by SEM and TEM as a function of dope pH and washing bath salt concentrations. The textural properties {mechanical resistance, moisture content) and diameter of the fibres have been determined.

Spinning was only possible when dope pH was higher than 11. An increase in dope pH from 11.5 to 13 induced a shear strength increase whereas the moisture content and the diameter of the fibres decreased . The structure of the fibres became more compact and changed from an aggregate of spherical particles to a tridimensional network. When dope pH was equal to 12. 6, the increase in washing bath salt content from 2 to 10 % NaCl produced more compact fibres.

At high dope pH, the protein aggregates were dissociated and the polypeptide chains were unfolded, which favoured the lining up of the macromolecules during the spinning process and increased the protein -protein interactions in the fibres.

High salt concentration in the washing baths produced a salting out effect which probably also enhanced the chain-chain interactions. Contrary to previous studies, protein strand orientation along the fibre axis and a double cortex-core structure have been demonstrated.

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