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1.2.17. Alginates: Properties and uses
Since alginates comprise an almost
indefinitely large family of polysaccharides,
where chemical composition and molecular
weight can vary within wide ranges (by
selecting different raw materials or by
controlled degradation), a correspondingly
wide range of properies are found. Such
differences are often basis for different
applications.
1.2.18. Gelation with Ca++ : Gel strength and Young’s modulus
When Ca++ ions are added to a solution of Na alginate containing sufficiently
long G-blocks, a rapid reaction takes place, leading to gelation. At a given
(fixed) alginate concentration the strength of the gel increases with increasing
NG>1 as shown below:
Gel strength’ is a rather inaccurate term. The symbol E used in the figure
refers to Young’s modulus, which is a measure of elasticity when the gel is
compressed. This is normally done in a texture analyzer, where a force (F) is
applied to the gel, and the corresponding compression (ΔL) is recorded:
Figure 23. Olives containing
pimiento made from alginate
and mashed bell pepper
Figure 24.