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ARS Home » Research » Publications at this Location » Publication #116098
Title: STEROL ESTER PRODUCTION USING LIPASE-CATALYZED REACTIONS IN SUPERCRITICAL CARBON DIOXIDE

Author
item King, Jerry
item SNYDER, JANET - RETIRED ARS EMPLOYEE
item FRYKMAN, HANS - FORMER ARS EMPLOYEE
item NEESE, ANGELA - FORMER ARS EMPLOYEE

Submitted to: Lebensmittel Untersuchung Und Forschung A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: The addition or natural inclusion of nutritionally-beneficial ingredients in food products has given rise to a new concept in the food industry known as nutraceuticals or functional foods. These foodstuffs besides serving the nutritional needs of the consumer also have implied a long range health or prophylatic benefit on the consumer's health if regularly consumed. Recently certain naturally-occurring chemicals known as phytosterol esters have been shown to reduce cholesterol levels in clinical tests on human subjects, and have fostered the introduction of several products based on inclusion of these substances in such foods as margarines and salad dressings. In this study, an all-natural synthesis for producing phytosterols was developed which makes use of the solubility of the components of phytosterol esters in compressed carbon dioxide (CO2) and a naturally-occurring catalyst known as an enzyme. When phytosterol components dissolved in compressed CO2 are passed over the enzyme bed, ver high yields (over 95%) of the desired esters are produced. The resultant products are free from any contaminating chemical solvents and ready for direct formulation into various food products as a nutritional supplement. The process has been designed for the continuous production of the phystosterol esters, making the synthesis attractive to industry.

Technical Abstract: Synthesis of sterol and stanol esters is of importance, due to their recent recognition and application in the food and nutraceutical industries as cholesterol-lowering agents. In this study, several enzymes were evaluated to determine the best catalyst and optimal conditions for the reaction between various fatty acids and cholesterol or sitostanol in supercritical carbon dioxide (SC-CO2). Using an analytical supercritical fluid extraction (SFE) unit, the lipase derived from Burkholderia cepacia, Chirazyme L-1, was determined to be the most selective for facilitating the desired reactions. Fatty acids C8 - C18, pressures between 3000 - 4500 psi, a temperature range of 40 deg C - 60 deg C, along with variable flow rates and initial static hold times, were used to evaluated the feasibility of the above reaction. The yield of the cholesterol esters, as measured by supercritical fluid chromatography (SFC), ranged from 90% for caprylic acid dto 99% for palmitic acid, while for the corresponding reaction between sitostanol and the same fatty acids produced yields of 92% for caprylic acid and 99% for palmitic acid, respectively. The extraction apparatus was modified to provide a continuous flow of the reagent fatty acid and sterol/stanol over the enzyme bed, thereby allowing continuous production of the desired esters which averaged a 99% yield under optimal conditions.