Plant secretions or exudates are substances

that ooze out form the pores of injured or

diseased plant tissues. They include gums,

rubber, pectin, resins, tannins, essential oils,

fatty oils, drugs, dyes, sugars, starches, and



4.1 GUMS


These are substances which are natural

derivatives of cellulose

carbohydrates and which are mucilaginous or

sticky when they are wet. They are sticky

substances obtained lrom the stems and

barks of trees.






They are soluble in water and some organic

reagents like alcohol, ether etc. A lot of gums

come from the Leguminosae, mainly from the

Tropics and Subtropics.


Examples of gums and their sources


Gum Arabic- Acacia senegal- fournd mostly in

NOrth Africa and Sudan. It is used 1n

Conlectionery, soft and alcoholic beverages. It is also used in pharmaceutical, cosme

thographic and offset preparations.It was extensively used as an adhesive, but this use

has almost entirely been replaced by synthetic

gum. Similarly its uses as a sizing and

finishing material in the textile industry have

also mostly given way to modern substitutes.

However, small quantities continue to be used

in paper making. Gum is also used to a

limited extent in polishes, contact insecticides

and pesticides, photographic emulsions and

pharmaceuticals. It belongs to the family

Sterculiaceae. Current production potential is

around 30,000 to 40.000 tonnes per annum,

of which bulk (80%) Originates in Sudan:

Nigeria being the second largest producer.










accounted for by the Sahelian count

Faso, Chad, Tanzania and Kenya).


timo for 70% to 800, the balance being


West Africa (Nigeria, Mali, Niger, Burkina


Karaya Gum-

It is obtained from Sterculia urens, a large uee

1n central India. In other to obtain the gum,

incisions are made into the heartwood and thee

gum oozes into the incisions and accumulates

as large irregular knobs.

Collected, sorted and graded. It is used in the

textile, COsmetic, cigar, past and ice cream

industries. Of all the gum karaya produced

only 10% is used as a food additive; the


They are then


remainder goes into pharmaceutical products.

The pharmaceulical apphhcations ot gum

karaya include medical colostomy bag fixings,

dental fixatives and bulk laxatives. Colostomy

bag fixings is the most commorn use of gum

karaya, in which the gum’s qualities are

difficult to equal.


Guar gum- Cyanops tetragonolobs.

Guar gum can best be described as a natural

food thickener extracted from the guar bean.

The guar seeds are de-husked, milled and

Screened to obtain the guar gum. The guar

plant, also known as a cluster plant, grows

primarily in Pakistan and the northern

regions of India. Guar gum has significantly

thickening ability. This has made it a popular

additive in products such as puddings and ice

creams. It retards ice crystal growth in food

ke 1ce cream and sherbet. The seceds are

manually or mechanically separated and

processed into flour or sold as split seeds.

Guar gum is an important cash Crop for the

lndian and Pakistani economies. It is also

used in the paper industries as additives to




Rubber is obtained from the milky juice or

latex of various erect and climbing woocy

plants ol the tropics and sub-tropics. It 1S a

COagulate elastic latex. Rubbers are polymeric

materials ‘endowed with the properies of

extensibility: Withthe



application of force, the molecules straighten

out in the direction in which they are being




pulled: on release from being extended, they


arrangements. It is formed in the cytoplasm of

laticifers as a by-product of metabolism and

accumulates in the vacuole. Most rubber


spontaneously recover their normal, random


plants belong to the family Moraceae (Lagos



Apocynaceae are of poor grades because of

high percentage of resin and p0or percent of



rubber) and

from the family


Euphorbiaceae (Para




There are about 50 spp available as sources

but only a few are of commercial importance.

These include










Panama rubber Castilla elastica


Indian rubber

Lagos silk rubber


-Landolphia rubber

-Cerea rubber


Fiscus elastica






Landolphia kirkii
















Updated: February 9, 2020 — 6:53 pm

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