Polymer Content (PC) was determined according to the method described by Peled et al. (1975). Polymer content was measured to determine the portion of oil that, after methanolysis, remained insoluble in methanol at 25°C. Subsequently, 250 mL methanol was added to a 500 mL conical flask containing 1% sulphuric acid and 2 g of a heated oil. The conical flask was placed on a hot-plate magnetic stirrer; the methanol-oil mixture was boiled under a reflux condenser for 2 h and cooled to 25°C. The methanolic miscella was thoroughly decanted off and the methanol-insoluble fraction was washed with 15 mL of methanol. The insoluble portion was dissolved in 40 mL petroleum ether (60-80°C) and then transferred to a pre-weighed flask. The solvent was initially evaporated by a rotary vacuum evaporator (NEB1001, Japan) and then by placing the flask in a vacuum oven for 2 h at 140±5°C. The weight of the polymers was then recorded.