LOCUST BEAN GUM

                              LOCUST BEAN GUM

Synonyms

Arobon; Carob gum, Ceratonia

 Biological Source 

This gum consists of endosperms of the seeds of Ceratonia siliqua Linn, family Leguminosae.

Geographical Source

The plant is found in Cyprus, Sicily and Egypt. It is cultivated easily but very sensitive to low temperature. It is produced in Spain, Greece, Algeria, Morocco, Israel, Italy and Portugal.

Cultivation and Collection

Carob is an evergreen tree growing to a height of about 10 metres and has luxuriant perennial foliage. The tree grows on rocky soil and has very long roots that penetrate up to 18 - 25 m and survive in an area where there is very little rain fall.

It starts bearing fruits only after three years. The plants start flowering in January to March every year, and the fully matured fruits are ready by October-November. The fruits (pods) are harvested by shaking the twigs and picked Fig. 8.10: Locust bean tree with pods up from the earth by hand and sent to market.

The locust bean fruits or carob are dark chocolate coloured, 10 - 20 cm long, 2.0 - 5 cm wide and 0.5 - 1.0 cm thick. The seeds are ovoid dark brown, very hard and weigh 0.21 g or 3.2 grains . The locust bean tree can be planted or even grafted.

Preparation and Purification of Gum

Locust bean pods consist of 9096 of pulp and 8 per cent of kernels. The pods are fed to kibbling machine. The kernels separated consist of 30 - 33 per cent of husk, germ (about 25 per cent) and endosperm (42 - 46 per cent) Preparation of high quality gum consists of separation of endosperm from embryo. Successful removal of Outer dark coloured husk decides the quality of the gum. DeCorticated seeds (dehisced seeds) split lengthwise and are separated from the embryo. The presence of yellow germ increases the rate of fermentation of the gum solutions in

further products. Hence, it must be thoroughly removed from the endosperm. It is then pulveri Colour and graded according to the mesh size. The normal mesh sizes available in Italian market are Odour 150,175 and 200.

Description

Gum is translucent-white, opaque at the edge, hard, horny and very difficult to break. It is Shape colourless, odourless and mucilaginous in taste. Locust bean gum has molecular weight of 3,10,000.

It is insoluble in alcohol, but is incompletely dispersed in water at room temperature. Most of the gum is dispersed in concentrations upto 5 per cent. The gum solutions are pseudoplastic. Gum is a neutral polysaccharide. Hence, pH has little effect on its viscosity in the range of 3 - 11. The viscosity of 2 per cent dispersion of gum powder in cold water at 25° C is about 1600 centipoises while in hot-water dispersed gum, it is about 3200  centipoises .

Uses

1.     It is useful as a stabiliser, thickener and binder in cosmetics; adsorbent and demulcent if - cohol. lts speci therapeutically.

2.     It is used as sizing and finishing agent in textiles and also as drilling mud additive. In food industry, it is used as substitute for starch.