189
(above 40%) gum arabic is highly viscous (forms gel like mass) and exhibits a
pseudoplastic behavior, whereas at lower concentrations it exhibits a Newtonian
behavior.
Gum Tragacanth
This complex heterogeneous polysaccharide occurs naturally as a slightly acidic,
calcium, magnesium or potassium salt with a molar mass of approximately
8.4 × 10
5
g/mol. It is obtained from the stems and branches of Astragalus gummifer
Labillardiere and other Asiatic species of Astragalus. These plants are mostly grown
in Turkey, Iran, Iraq, Syria, Lebanon, Afghanistan, Pakistan and in some parts of
Russia. The two main components of tragacanth are the water swelling component
and the water soluble component. Most times this gum contains small amounts of
Uronic acid (3%). The high molar mass tragacanthic acid fraction has a rod like
molecular shape and the main chain is formed by (1 → 4) linked D-galactose residues with side chains of D-xylose units attached to the main chain by (1 → 3) linkages. The neutral water soluble tragacanthin is highly branched arabinogalactan
with a spherical molecular shape and is composed of (1 → 6) and (1 → 3) linked
D-galactose with attached chains of (1 → 2), (1 → 3) and (1 → 5) linked L-arabinose.
Some of the important physiochemical characteristics of tragacanth gum are acid
resistance, resistance to degradation at low pH and bifunctional emulsifying ability.
At lower concentrations, it exhibits pseudoplastic behavior. An excellent formulation was seen with an average size of 22 nm and 100% microbial reduction after
12 h stirring, when tragacanth was used as an encapsulating agent.
Pectin
Pectin is a very complex, non-random structural hetero polysaccharide comprising
of homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II. The average molecular weight falls in the range of 50,000–180,000 Da. The esterification of
the carboxyl group with methanol, classifies pectin into two groups high methoxyl
pectin (HM) which has 50–80% esterified carboxyl group and low methoxyl pectin
(LM) which has 25–50% esterified carboxyl group. The first reported attempt to
study pectin was by Henri Braconnot in 1825. The esterification degree, molecular
weight and extraction conditions determines stability, gelling, and textural properties of pectin and thus it finds ample use in food formulation. The type of pectin,
concentration of pectin, modification of hydroxyl methoxy pectin, and temperature
determine gelling process and consequently gelling activity. Pectin is soluble in
water and insoluble in most organic solvents. It exhibits Newtonian behavior at
lower concentration and at higher concentration exhibits pseudoplastic behavior.
Dietary Gums
(above 40%) gum arabic is highly viscous (forms gel like mass) and exhibits a
pseudoplastic behavior, whereas at lower concentrations it exhibits a Newtonian
behavior.
Gum Tragacanth
This complex heterogeneous polysaccharide occurs naturally as a slightly acidic,
calcium, magnesium or potassium salt with a molar mass of approximately
8.4 × 10
5
g/mol. It is obtained from the stems and branches of Astragalus gummifer
Labillardiere and other Asiatic species of Astragalus. These plants are mostly grown
in Turkey, Iran, Iraq, Syria, Lebanon, Afghanistan, Pakistan and in some parts of
Russia. The two main components of tragacanth are the water swelling component
and the water soluble component. Most times this gum contains small amounts of
Uronic acid (3%). The high molar mass tragacanthic acid fraction has a rod like
molecular shape and the main chain is formed by (1 → 4) linked D-galactose residues with side chains of D-xylose units attached to the main chain by (1 → 3) linkages. The neutral water soluble tragacanthin is highly branched arabinogalactan
with a spherical molecular shape and is composed of (1 → 6) and (1 → 3) linked
D-galactose with attached chains of (1 → 2), (1 → 3) and (1 → 5) linked L-arabinose.
Some of the important physiochemical characteristics of tragacanth gum are acid
resistance, resistance to degradation at low pH and bifunctional emulsifying ability.
At lower concentrations, it exhibits pseudoplastic behavior. An excellent formulation was seen with an average size of 22 nm and 100% microbial reduction after
12 h stirring, when tragacanth was used as an encapsulating agent.
Pectin
Pectin is a very complex, non-random structural hetero polysaccharide comprising
of homogalacturonan, rhamnogalacturonan-I and rhamnogalacturonan-II. The average molecular weight falls in the range of 50,000–180,000 Da. The esterification of
the carboxyl group with methanol, classifies pectin into two groups high methoxyl
pectin (HM) which has 50–80% esterified carboxyl group and low methoxyl pectin
(LM) which has 25–50% esterified carboxyl group. The first reported attempt to
study pectin was by Henri Braconnot in 1825. The esterification degree, molecular
weight and extraction conditions determines stability, gelling, and textural properties of pectin and thus it finds ample use in food formulation. The type of pectin,
concentration of pectin, modification of hydroxyl methoxy pectin, and temperature
determine gelling process and consequently gelling activity. Pectin is soluble in
water and insoluble in most organic solvents. It exhibits Newtonian behavior at
lower concentration and at higher concentration exhibits pseudoplastic behavior.
Dietary Gums