Knowde Enhanced TDS
Identification & Functionality
- Ingredient Name
- Food Ingredients Functions
- Ingredients
- Gum Karaya
- Technologies
- Product Families
- Sources
Gum Karaya, or sterculia gum, is the dried exudate of Sterculia Urens,
a tree native to India, which is the sole source of supply. The trees
grow 9 meters high, and their cultivation and gum collection are
closely controlled by the government. As with other exudate gums,
the trees are tapped or drilled, and exudation begins immediately and
continues up to several days in the form of large, irregular tears of
lumps, which may weigh up to 5 pounds. The average tree can be
tapped about five times during its lifetime, with a yield of 1 to 4.5 kg
per season for its lifetime. The sap, or exudate, is allowed to dry on
the tree. The native collectors pick this crude gum, which is sold to
dealers in Bombay. These gum tears are then cleaned, broken into
fragments less than 25 mm in diameter, sorted and graded according
to color and purity before selling to importers and processors.
The best quality gum is picked in April, May and June, before the
monsoon season. In September, the gum is again picked. This fall crop
has a grayish color and is less viscous. The total crop is about 5 million
kilograms. The United States imports about 75—80% of this crop.
Colony evaluates all incoming raw materials according to impurity
content, solution viscosity and color. The three highest grades of
Karaya are white to tan in color, translucent, and have less than 3%
bark and foreign organic matter. The technical grades are brown and
have more impurities. After approval, Colony Gums utilizes a
processing system of size reduction, aspiration, and density-table
separation to remove bark, fibers, sand, and small pebbles from the
gum. The Karaya is further processed and blended to custom
specifications for mesh size, purity, color and viscosity.
Features & Benefits
- Food Ingredients Features
- Product Properties
- Physical
Karaya has a slightly acetous odor and taste. Its powder is light
gray to pinkish gray. Cost is based on color and purity. There is no
distinct correlation between viscosity and grade. Where viscosity is
important, the powdered Karaya should be used within six months
after processing, because its viscosity decreases with age.- Solubility
Karaya is one of the least soluble of the gums. It does not dissolve
in water to give a clear solution but absorbs water rapidly to form
viscous colloidal sols at low concentration. The finer-mesh gum
hydrates much more rapidly than coarse gum. The fine powder
gives a smooth sol, while coarse granules will yield a lumpy sol orhigh-humidity storage is also harmful to the viscosity stability. In
solution, karaya is more viscous when hydrated cold rather than hot.
Heating at boiling temperatures for longer than two minutes particularly
reduces viscosity.
dispersion. Up to 4% gum may be hydrated in cold water to give a
viscous gel-like paste of uniform smoothness and texture. Karaya
will form viscous sols in 60% alcohol, but is insoluble in higher
concentrations of alcohol.- Viscosity
Gum Karaya, in the dry state, loses viscosity on aging and may
develop an acetic taste. The fine-powdered gum suffers greater
viscosity loss than the granules or the whole exudates. Climate
and time of harvest also affect viscosity. High-temperature or- Chemical Characteristics
Structurally, Karaya is a complex acetylated polysaccharide with a
molecular weight of about 9.5 million It contains about 8% acetyl
groups, with an acid number of 13.4–22.7, depending on the Karaya
source and its age. Free acetic acid is split off on aging. Increased
temperature and humidity and fine particle size increase the rate of
acetic acid formation. Karaya contains about 43% D-galacturonic acid,
13% D-galactose, and about 15% L-rhamnose. Powdered Karaya contains
about 14–17% moisture, less than 1% acid-insoluble ash, and less than
3% insoluble matter of bark. The pH of a 1% solution is about 4.6. Above
pH7, alkali irreversibly transforms the characteristics of short-bodied
Karaya solution into a ropy, stringy mucilage. This has been ascribed to
deacetylation of the Karaya molecule
Applications & Uses
- Markets
- Applications
- Food & Nutrition Applications
- Qualities
- Stabilizer
- Thickening agent
- Binding aid
- Uses
- Tissue paper
- Food
- Colored fabric
- Cosmetics
- Pharmaceuticals
Food
Karaya, at 0.2 –o.4% alone, or at 0.15% locust bean gum, stabilizes ice
pops and sherbets by preventing the formation of large ice crystals
and preventing the migration of free water or syneresis. Karaya, used
in meringue powders, enables a greater volume of meringue to be
prepared from a fixed amount of protein. In cheese spreads, 0.8% or
less, Karaya is used to prevent water separation and to increase
spreadability. Its acidic nature is not objectionable in these dairy
products. Karaya, Carrageenin and locust bean gums have been
used to stabilize natural and imitation whipping cream.
Pharmaceutical and Cosmetics
A large part of the Karaya imported into the United States is utilized
in two types of products. As a denture adhesive, the powdered gum
is dusted on the dental plate and swells when it touches the moist
surfaces of the mouth. This results in a more comfortable and tighter
fit of the plate. The rapid swelling of the Karaya particles, their relative
insolubility, and their resistance to bacterial and enzymatic breakdown
make the gum suitable for this use. A small amount of mild alkali
added to the powder improves the adhesiveness.Paper Industry
Gum Karaya is used as a binder to make long-fibered, lightweight
papers, such as condenser tissues and fruit-wrap tissues. These long
fibers form clusters or flocks in the paper web. Karaya effectively
deflocculates these fibers and maintains their uniform distribution in
the paper web, resulting in improved formation and strength in the
lightweight sheets. Before adding to the pulp suspension, the acetyl
groups of Karaya must be removed by treating the gum with ammonia
or other weak alkali. This exposes more active carboxyl and hydroxyl
groups and increases the binding of the gum to the cellulose fibers. This
deacetylated gum is added to the pulp suspension at about 1 kg/200 kg
of pulp. This use of Karaya in the paper industry is a very limited but
important application in lightweight papers made from long cellulose
fibers.
Textile Industry
Karaya is used as a thickener for the dye in the color printing on
cotton fabrics. For this use, the Karaya must be cooked in water under
pressure to make the Karaya more soluble. Under these conditions, it
forms a smooth, homogeneous, translucent, colloidal dispersion of
15—18% dry solids.
Technical Details & Test Data
- Compatibility
Karaya is compatible with most other gums, as well as proteins
and carbohydrates. Pyrilamine maleate, a strong hydrotrope and
antihistaminic, and Karaya are incompatible. Karaya dispersions lose
viscosity when certain strong electrolytes are added in small amounts.
Alkalies make the Karaya sol very ropy.- Preservatives
The viscosity of Karaya sols remains constant for several days.
Since these sols are subject to bacterial attack, preservatives
are recommended. Benzoic or sorbic acid, methyl and proply
parahydroxybenzoate, glycerol, propylene glycol, chlorinated
phenols, formaldehyde, and mercuric salts are suitable.