Microwave-Assisted Extraction and Physicochemical Evaluation of Oil from Hevea brasiliensis Seeds

The rubber tree (Hevea brasiliensis) is exploited mainly for latex in view of its economic importance. However, one of its auxiliary products, the rubber seed, does not find any major applications, and hence, even the natural production of seeds itself remains underutilized. In this study, microwave-assisted Soxhlet extraction is used as a green alternative to extract the oil from seeds at a reaction time of 90 min and microwave power of 300 W. The objective of the study is to evaluate the effects of the processing conditions, including drying time, temperature, solid-solvent ratio, and extraction solvent, on the yield of rubber seed oil. Moreover, the microwave-assisted aqueous extraction (MAAE) under acidic conditions is also investigated. Based on the results, n-hexane gave the best yield at an optimized 1:20 seed-hexane ratio at 72 degrees C compared with the conventional Soxhlet method and the acidic MAAE. Furthermore, the chemical characteristics of the oil showed a high value of free fatty acids (% FFA) (1.15-7.61%) and an iodine value (IV) that ranges from 100-150. As a semi-drying oil, rubber seed oil (RSO) can be used as an ingredient for surface coating and in the formulation of products where the presence of unsaturation is important.