Chemistry Reference
In-Depth Information
Fig. 5.1
Structure unit of guar gum [
38
]
The purification of guar gum is the basis of developing its derivatives and graft
copolymers as well as studying the corresponding mechanism. Singh groups [
39
]
reported a purification method of gum as follows: the 2.5 % (w/v) solution of GG
was prepared by continuous stirring for 12 h at 60
C and then precipitated with a
standard barium hydroxide solution. The formed complex was separated and taken
in 1 M acetic acid and stirred for 8 h and precipitated with ethanol. After washed
with 70 %, 80 %, 90 %, and 95 % ethanol, the sample was purified by dialysis and
filtration through 0.45
μ
m Millipore membranes (Millipore, Milford, MA).
5.2.1.2 Locust Bean Gum
LBG is a commercially available water-soluble
-1,4-polysaccharide obtained from
the seed of the carob tree (
Ceratonia siliqua L
.) and is a galactomannan consisting
of a mannose backbone with single side chain galactose units (Fig.
5.2
)[
40
-
42
]. It
can dissolve in water at 85
C to form a viscous solution with the pH values of
5.4-7.0, and the solution can further form gel by adding sodium tetraborate. LBG is
also soluble in LiCl-DMSO solutions. The viscosity is stable in the pH range of
3.5-9.0 and is not affected by Ca
2+
and Mg
2+
ions. But the acid or oxidizer will
make the LBG salting out and reduce the viscosity. LBG can be used as emulsifier,
thickener, stabilizer, and gelling agent [
43
,
44
]. It can create a cream form, and so
usually used for cream structure nature and usually used for dairy products and ice
cream, jams, jellies, and cream cheese to improve the smear performance.
The typical preparation method of LBG is as follows: the endosperm of the
legume beans was crushed after being roasted, and then extracted with hot water to
remove the insoluble matters. After the extraction solution was concentrated, 95 %
ethanol solution was added and the white floc was obtained. The solid was
separated, dried, and smashed to obtain the product.
β
