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functional groups to the natural gums. This may include the introduction of hydrophobic, acidic, basic, or other functionality into polysaccharide structures that can
alter the properties of materials based on these substances. For example, attachment
of carboxyl groups, carboxymethyl groups, polyacrylamide groups, phosphate
groups etc., has all been extensively investigated for such purposes. The introduction of new functional groups changed the charges, aggregation state of molecular
chains, hydrophilic–hydrophobic capability, complexing capacity, stimuli-response
ability, and rheological behavior of gums, and so the application domain of gums
was greatly extended. But, the derivatization of gums can only improve the properties to a finite degree because the number of introduced functional groups is less and
the molecular weight of gums cannot be increased by the simple modification with
small molecules. Graft polymerization is anticipated to be a quite promising technique for modifying the properties of a polymer, and the modification of natural
polymer materials by graft copolymerization. It offers the opportunity to tailor their
physical and chemical properties, functionalize biopolymers to impart desirable
properties onto them, and combine the advantages of both natural and synthetic
polymers (Battaerd and Tregear 1967 and Kalia et al. 2011).
Classification of Gums
Gum Arabic
Being one of oldest known natural plant gums-gum acacia or gum arabic is a complex mixture of arabinogalactan oligosaccharides, polysaccharides and glycoprotein. It is obtained from the branches of Acacia Senegal (L) Willdenow or close
species of Acacia (leguminosae family). This branched chain, complex polysaccharide exists in nature as a neutral or slightly acidic (D-glucuronic) salt of complex
polysaccharides containing calcium, magnesium and potassium ions. Its backbone
constitutes of 1,3-linked β-D-galactopyranosyl units and side chains contain two to
five 1,3- linked β-D-galactopyranosyl units. Both the main and the side chains contain units of α-L-arabinofuranosyl, α-L-rhamnopyranosyl, β-D-glucopyranosyl and
4-O-methyl-β-D-glucopyranosyl. This gum is available worldwide and is mainly
produced in the tropical and subtropical regions of Africa, India, Australia, Central
America and the Republic of Sudan with Sudan being the largest producer. The
Acacia senegal and A. laetia are two main species providing this gum and about
80% of commercial production comes from A. sengal. It is important to note that the
chemical composition of this gum may vary according to the source and age, climatic conditions (soil, environment, and rainfall), method of extraction, age of the
tree, and consequently the molecular weight of the gum which varies from 250,000
to 1,000,000. Gum arabic is colorless, odorless, tasteless and is highly soluble in
water. It is widely used as a stabilizer, emulsifier, flavoring agent, thickener or surface finishing agent and also retards sugar crystallization. At higher concentrations
P. Chatur et al.
functional groups to the natural gums. This may include the introduction of hydrophobic, acidic, basic, or other functionality into polysaccharide structures that can
alter the properties of materials based on these substances. For example, attachment
of carboxyl groups, carboxymethyl groups, polyacrylamide groups, phosphate
groups etc., has all been extensively investigated for such purposes. The introduction of new functional groups changed the charges, aggregation state of molecular
chains, hydrophilic–hydrophobic capability, complexing capacity, stimuli-response
ability, and rheological behavior of gums, and so the application domain of gums
was greatly extended. But, the derivatization of gums can only improve the properties to a finite degree because the number of introduced functional groups is less and
the molecular weight of gums cannot be increased by the simple modification with
small molecules. Graft polymerization is anticipated to be a quite promising technique for modifying the properties of a polymer, and the modification of natural
polymer materials by graft copolymerization. It offers the opportunity to tailor their
physical and chemical properties, functionalize biopolymers to impart desirable
properties onto them, and combine the advantages of both natural and synthetic
polymers (Battaerd and Tregear 1967 and Kalia et al. 2011).
Classification of Gums
Gum Arabic
Being one of oldest known natural plant gums-gum acacia or gum arabic is a complex mixture of arabinogalactan oligosaccharides, polysaccharides and glycoprotein. It is obtained from the branches of Acacia Senegal (L) Willdenow or close
species of Acacia (leguminosae family). This branched chain, complex polysaccharide exists in nature as a neutral or slightly acidic (D-glucuronic) salt of complex
polysaccharides containing calcium, magnesium and potassium ions. Its backbone
constitutes of 1,3-linked β-D-galactopyranosyl units and side chains contain two to
five 1,3- linked β-D-galactopyranosyl units. Both the main and the side chains contain units of α-L-arabinofuranosyl, α-L-rhamnopyranosyl, β-D-glucopyranosyl and
4-O-methyl-β-D-glucopyranosyl. This gum is available worldwide and is mainly
produced in the tropical and subtropical regions of Africa, India, Australia, Central
America and the Republic of Sudan with Sudan being the largest producer. The
Acacia senegal and A. laetia are two main species providing this gum and about
80% of commercial production comes from A. sengal. It is important to note that the
chemical composition of this gum may vary according to the source and age, climatic conditions (soil, environment, and rainfall), method of extraction, age of the
tree, and consequently the molecular weight of the gum which varies from 250,000
to 1,000,000. Gum arabic is colorless, odorless, tasteless and is highly soluble in
water. It is widely used as a stabilizer, emulsifier, flavoring agent, thickener or surface finishing agent and also retards sugar crystallization. At higher concentrations
P. Chatur et al.