Abstract-Mango peels, wastes generated from fruit can processing, are a good source of functional ingredients such as phenolic compounds that has potential antioxidant properties. This study investigated the extraction of phenolic compounds from mango peels using subcritical water extraction (SCW). Experiments were performed in a batch laboratory-built equipment (50 ml volume of vessel) immersed in oil bath and temperatures ranging from 160 to 220 °C, extraction time of 30 to 120 min., material particle sizes of 30 to 70 mesh, solid to water ratio of 1:10 to 1:50 and pH of solution 2 to 8. The highest phenolic content was obtained 50.25 mg GAE / g DW at the condition as follows: 180 °C, 90 min, solid to water ratio as 1:40 and pH 4. The amount of phenolic compounds from mango peels using SCW extraction was higher than that using soxhlet extraction at extraction time 60 min as 1.5 times. SCW extraction might be an alternative green technology for phenolic compounds extraction from agricultural wastes which substitute conventional method using organic solvents.Index Terms-Subcritical water extraction, phenolic compounds, mango peels.

The molar ratio of methanol to rubber seed oil (RSO), catalyst loading, and the reaction time of RSO biodiesel production were optimized in this work. The response surface methodology, using the Box–Behnken design, was analyzed to determine the optimum fatty acid methyl ester (FAME) yield. The performance of various nanomagnetic CaO-based catalysts—KF/CaO-Fe3O4, KF/CaO-Fe3O4-Li (Li additives), and KF/CaO-Fe3O4-Al (Al additives)—were compared. Rubber seed biodiesel was produced via the transesterification process under subcritical methanol conditions with nanomagnetic catalysts. The experimental results indicated that the KF/CaO-Fe3O4-Al nanomagnetic catalyst produced the highest FAME yield of 86.79%. The optimum conditions were a 28:1 molar ratio of methanol to RSO, 1.5 wt % catalyst, and 49 min reaction time. Al additives of KF/CaO-Fe3O4 nanomagnetic catalyst enhanced FAME yield without Al up to 18.17% and shortened the reaction time by up to 11 min.

Mangoes are consumed for 572,000 metric tons per year that leads to 57,200 metric tons of mango seeds that need to be eliminated. In Egypt and India, there are many researches about composition in mango seed kernel and their activities. They have found that there are fatty acids and phenolic compounds in mango seed extracted 1. These composition could be used in many industries such as food preservation, cosmetology and food ingredients 2,3. Typically, mango seed extraction uses methanol and ethanol as solvent extraction 4. These solvents cause toxic in extracted substances and resulting in pollutions. Supercritical carbon dioxide extraction has been proposed as nonsolvent residues and better retention of aromatic compounds as an alternative technique to conventional solvent extraction and mechanical pressing for extracting essentential oils 5-7 , seed oil 8 and carotenoids 9 from various plant materials. Extracted volatile oil from Aquilaria subnitegra by using supercritical carbon dioxide and hydrodistillation. The maximum yield was reached at 4.43 % from supercritical carbon dioxide at 25 MPa, 50 °C and 3 g/min of carbodioxide flow rate. Whereas the yield from hydrodistillation process was only 0.23 % 10. Moreover, extracted patchouli oil by using steam distillation and supercritical carbon dioxide. They have found that maximum yield of patchouli oil was reached 5.07 % at 14 MPa and 40 °C of supercritical carbon dioxide extraction that more than steam distillation method 11. So, supercritical fluid could be used to extract herbs and it could extract oil at

Abstract-Seed of rambutan as a waste of products from the canned fruit industry and was extracted by supercritical carbon dioxide (ScCO 2 ) using CO 2 as a solvent, maceration and soxhlet extraction using ethanol as the solvent. An optimization study of ScCO 2 extraction using response surface methodology was performed and 3D response surfaces were plotted from the mathematical models. The optimal conditions based on combination responses were: pressure (X 1 ) at 34.8 MPa, temperature (X 2 ) at 56.7 o C, the amount of ethanol (X 3 ) in volume 14.5 ml. These optimum conditions of percent oil yield of 30.38. Therefore, it is considered that the ScCO 2 extraction is competitive with conventional extraction as shorter extracting times, high percent oil yield, less organic solvent and eco-environmental friendly. The extracted oil could be used in the cosmetic and food industry.Index Terms-Rambutan seed, supercritical carbon dioxide extraction, fatty acid, response surface methodology.

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