What are the methods used to extract sesame oil?

Sesame oil, also known as fragrant oil or sesame seed oil, is a semi-drying oil carefully extracted from sesame seeds. Its history dates back to ancient times, and it is highly valued for its rich aroma. Whether used for dressing noodles, salads, or making fillings, sesame oil plays an indispensable role in flavoring.

Overview of Sesame Oil Extraction Methods

Water Substitution Method

Also known as the small mill method, this traditional technique has been used in China for over 400 years. It involves grinding sesame seeds with a stone mill to produce a sesame paste base. Then, the paste is mixed with hot water in specific proportions, stirred, and left to settle, allowing oil and water to separate effectively. Although this method yields less oil, the quality is superior—it releases more aromatic compounds and retains more of the sesame's nutritional value.

Mechanical Pressing Method

This approach uses mechanical force to squeeze oil from oil-bearing materials. While it achieves a higher yield, the nutritional value and aroma are slightly inferior compared to the water substitution method.

Solvent Extraction Method

Also known as leaching, this method leverages the chemical affinity between oil and certain solvents. Sesame material is soaked, and the oil dissolves into the solvent. Through distillation, the solvent is separated from the crude oil. This method offers high yield and low cost, but it compromises the original fragrance. Since sesame has a high oil content and is not ideal for direct solvent extraction, it’s often pre-pressed mechanically, then the residual sesame cake is leached to retrieve the remaining oil.

Aqueous Enzymatic Extraction

A modern innovation, this method involves finely grinding sesame to rupture cell walls. The material is soaked in water, allowing it to absorb and swell. Enzymes are then added to further break the walls and release intracellular oil droplets. Finally, the oil is separated via centrifugation. This technique not only extracts oil efficiently but also recovers valuable proteins and carbohydrates, preserving the oil's natural nutrients. It offers higher yield and better oil quality with no need for refining, and produces no waste or pollution. Though research abroad is quite advanced, the method is still in the experimental stage and not yet ready for industrial application.