ECONOMICALLY USEFUL PLANTS OF SRI LANKA . PART VI . * EXPLOITATION OF SEED FATS OF MANGO AND RAMBUTTAN FOR THE PRODUCTION OF SOAP

Soaps have been prepared from the seed fats of mango and rambuttan. Their properties have been compared with those of commercial soaps. The results show that rambuttan seed, with its high fat percentage, could. be exploited in the soap manufacture.


Introduction
Large quantities of mango and rambuttan seeds are discarded seasonally in Sri Lanka.In India, butter from mango seed fat is obtained and is used as food.The possibility of utilising mango seed butter in Sri Lanka has been suggestede4 In this paper, the soap obtained from the mango seed fat is compared with soaps available in the market.Soap from another seed which is discarded seasonally, rambuttan, has also been prepared.

Results and r is cuss ion
The mango seed, rambuttan seed and coconut kernel fat percentages are given in Table 1.All are solid fats.The rarnbuttan seed has a fat content of 43% whereas the mango seed has a fat content of only 7%.The fat content of rambuttan 'seeds is comparatively high and thus it could be economically exploited.
From Table 2, it can be seen that rarnbuttan seed fat has 5Wo saturated acids whereas the fat from coconut kernel has 92% saturated acids.The .mango seed fat is not very different to that of rambuttan seed fat and has 47% saturated acids.Mango and rambuttan seed fats are very similar in having high content of oleanolic acid.These seed fats, though solids, are more unsaturated than the coconut kernel fat.However, the melting points of the mango and rarnbuttan fats are higher since they contain longer carbon chain fatty acids than those of coconut fat.Like the coconut kernel fat, the solid fats from mango and rarnbuttan seeds could be used in the soap manufacture.These soaps have been prepared by saponifying the fats using sodium hydroxide by the cold-process.! The properties of these soaps have been compared with those of two common soaps available in the market.
The results are given in Table 3.Though the matters insoluble in ethanol are high for the mango and rambuttan soaps, they are within the maximum weight per cent of 4 permitted for soft soaps.The present study therefore, shows that-the seed fats of mango and -. rambuttan can be used t o .manufacture soap.We suggest that with the escalating prices of coconut oil (and hence soaps), attempts should be made in Sri Lanka to collect the discarded seeds, extract fats and use them either separately or mixed with coconut oil in the.manufacture of.soap.Rambuttan seed, with its high fat content, could therefore be economically exploited in the soap manufacture.

Experimental
Mango and rarnbuttan seeds were collected during their respective seasons.
The kernels were separately extracted with light petrol: The per cent fat is given in Table 1.The seed fats were saponified using sodium hydroxide.The amount of sodium hydroxide required t o saponify a known quantity of the fat was calculated from the saponification value of each fat.3The total fatty matter, substances insoluble in ethano1,free caustic alkali and total unsaponifiable matter were obtained for the mango soap, rambuttan soap and for two commercially available soaps (Sunlight and Lifebuoy) by the use of testing ' methods given by the Bureau of Ceylon Standards.The results are tabulated (Table 3).The pH values of these soaps are presented in Table 3.The acid components of the fats were analysed by gas chromatography (GC).The fats were converted to the methyl esters for GC analysis as follows: The fat (100 mg) was refluxed with benzene (1 ml), boron trifluoride in methanol (20% ; 0.1 ml), and methanol (2 ml) for 20 min.Solvent was evaporated,   Total unsaponified matter percent by weight water was added and the ester was extracted with ether.The etherea! layer was dried (anhydrous magnesium sulphate) and evaporation of ether gave the esters.GC analysis of the esters was carried out on a Varian moilel 24.40 chromatograph equipped with a flame ionisation detector.The chromatograph was fitted with glass columns (1.8m x 2 mm i.d) packed with 10% SP 2340 coated on 100/200 chromasorb W. The column was maintained at 19o0C.Argon was used as the carrier gas at a flow rate of 30 rnlmin-l.The identification was by peak boosting and by comparing retention times; The fatt).acids identified and their compositions are given in Table 2.

Table 1 .
Fat Content of Coconut Kernel, Mango and Ramburran Seeds.

Table 2 .
Percent Composition of the Acid Components of Fats .