I think boiling with hot water and then allowing to cool will give the mucilage portion if they are really in a high quantity. I have not worked on this but some of my colleagues did and they noticed the mucilaginous portion upon cooling. Hopefully give it a try and see the result. You may succeed. Gud Luck 

Regards 

Have you tried alcaline hydrolysis to hydrolyze proteins and nucleic acids and to saponify lipids ? 

Dear Nidal

Check the following publications on separation and characterization of plant mucilage.

1. Baveja, SK, Ranga Rao KV and Arora J. Examination of gums and

mucilage as sustaining materials in dosage forms. Indian J

Pharm Sci 1988; 50: 89-92.

2. Wahi SP and Sharma VD. “Studies on suspending property of

mucilages of Hygrophila spinosa T.Anders and Hibiscus

esculentus Linn. Indian Drugs 1985; 22(9): 500-502.

There are many more references in Google. Search for extraction of plant mucilages.

Good luck.

Mucilage is generally secreted from glands which are present in fruits and leaves. This is an thick sticky material contains water, proteins, carbohydrates, minerals and lipids. You can separate crude mucilage by roiting the fruits after cutting them from middle in a horizontal vertis, pour it in a sterilized vessel. Or extract it in cold water by crushing and messing of fruit pulp or thick grossy leaves. 

Check this thread on a similar subject:

https://www.researchgate.net/post/What_is_the_best_procedure_for_extracting_the_mucilage_from_a_plant_organ

Cold water infusion. Leave them in cold water over the night (as cold infusions take longer). Don't use boiling water -mucilage gets denatured by boiling water to some extent.