2009_Book_FoodChemistry

4.4 Polysaccharides 311
(4.143)
As a result of the strong cross-linkage, this
polysaccharide is insoluble in water and resistant
to enzymes and microorganisms. However, it
swells greatly even in cold water. Suspensions
have a pasty consistency at concentrations of
more than 3%.
4.4.4.8.3 Utilization
Karaya gum is used as a water binder (soft
cheese), a binding agent (meat products like
corned beef, sausages), a stabilizer of protein
foams (beer, whipped cream, meringues), and as
a thickener (soups, sauces, salad dressings, mayonnaise,
ketchup). It increases the freeze-thaw
stability of products, prevents synaeresis of gels,
and provides “body”.
contains 10–15% moisture, 5–6% protein, 2.5%
crude fiber and 0.5–0.8 ash. The plant is cultivated
for forage in India, Pakistan and the United
States (Texas).
4.4.4.9.2 Structure, Properties
Guaran gum consists of a chain of β-Dmannopyranosyl
units joined by 1 → 4 linkages.
Every second residue has a side chain, a D-galactopyranosyl
residue that is bound to the
main chain by an α(1 → 6) linkage (cf. Formula
4.126).
4.4.4.9 Guaran Gum
4.4.4.9.1 Occurrence, Isolation
Guar flour is obtained from the seed endosperm of
the leguminous plant Cyamopsis tetragonoloba.
The seed is decoated and the germ removed. In
addition to the polysaccharide guaran, guar flour
(4.144)
Guaran gum forms highly viscous solutions (Table
4.21), the viscosity of which is shear rate dependent
(Fig. 4.23).