Method for producing lignan concentrates from sesame meal using supercritical carbon dioxide fractional extraction

Process for high-purity concentration of sesame meal lignans using two-stage high-pressure/low-pressure supercritical CO2 and lipase esterification

This technology involves fractionally extracting sesame meal with high-pressure supercritical carbon dioxide to obtain high-lignan sesame oil. Ethanol is then added to convert neutral lipids into fatty acid ethyl esters, followed by low-pressure supercritical carbon dioxide extraction to remove the ethyl esters, leaving behind a concentrated lignan residue. Purity can be further enhanced through non-polar solvent crystallization if necessary.

Lignans in sesame, such as sesamin, sesamolin, and sesamol, offer various physiological benefits, including antioxidant effects, cholesterol reduction, and improved liver function. However, sesame meal—the byproduct of pressing sesame oil—has largely been sold at low prices for animal feed or fertilizer. There has been a lack of economical and simple methods to extract lignans from this byproduct with high yield.

In this process, an initial fraction (0.3–1 parts by weight per 100 parts of sesame meal) is collected at 35–45℃ and 45–51 MPa to obtain sesame oil with over 3% lignan content. Ethyl esterification is then performed by stirring for 10–14 hours at approximately 40℃ using lipase derived from Thermomyces lanuginosus immobilized on a Duolite A568 carrier. Subsequent removal of ethyl esters under low-pressure conditions (58–62℃, 11.5–11.9 MPa) yields a primary concentrate with over 25 wt% lignans. Further processing via reflux cooling with n-hexane, low-temperature crystallization, and vacuum drying produces a secondary concentrate with over 79 wt% lignans. This technology adds value to sesame meal—previously discarded as feed—by converting it into three distinct products: oil, intermediate concentrate, and high-purity lignans, suitable for health supplements, premium high-lignan sesame oil, and antioxidant cosmetics.

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Key Features:

• Step of obtaining a primary extract by supercritical extraction of sesame meal at 35–45℃, 45–51 MPa, and a CO2 flow rate of 2–3 L/min
• Step of inducing an ethyl esterification reaction by adding lipase derived from Thermomyces lanuginosus immobilized on a Duolite A568 carrier to a mixture of the primary extract and ethanol
• Step of obtaining a primary lignan concentrate by removing ethyl esters from the ester-converted primary extract via supercritical extraction at 58–62℃ and 11.5–11.9 MPa
• Step of obtaining a secondary lignan concentrate by refluxing the primary lignan concentrate with a non-polar solvent, inducing crystallization, filtering, and vacuum drying

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This invention was developed with support from the Ministry of Agriculture, Food and Rural Affairs for the optimization of high-lignan sesame oil and lignan concentrate production from sesame meal.

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