Extraction and Quality Assessment of Soybean Oil and Its Application in Fatty Acid Methyl Ester Production

Soybeans are a globally important oilseed crop valued for their nutritional and industrial applications. This study aimed to evaluate the physicochemical properties of soybean oil extracted from seeds collected in Kathmandu, Nepal.Oil was extracted using a Soxhlet apparatus with n-hexane as the solvent. Seed moisture content was determined gravimetrically. The extracted oil was characterized for saponification value, acid value, peroxide value, ester value, free fatty acid content, density, specific gravity, boiling point, and percentage yield. The oil was further converted into fatty acid methyl esters through transesterification, and ester formation was confirmed using thin-layer chromatography. Gas chromatography-mass spectrometry was used to attempt a detailed analysis of the esters.The soybean seeds had a moisture content of 9.25%. Oil extraction yielded 7.8% with a specific gravity of 0.93 at 25°C. Saponification, acid, peroxide, and ester values were 198.80 mg KOH/g, 0.6725%, 3.33 mmol/kg, and 198.17 mg KOH/g, respectively. TLC confirmed the formation of methyl esters, although GC-MS analysis did not provide conclusive results. The extracted soybean oil exhibited physicochemical properties suitable for food or industrial use after refining. Transesterification successfully produced fatty acid methyl esters, demonstrating potential for biodiesel or other industrial applications. This study provides region-specific characterization of soybean oil from Kathmandu, offering baseline data for local industrial and nutritional applications.