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Submitted to: Industrial and Engineering Chemistry Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/28/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Monoglycerides are food emulsifiers used to improve specific properties of foods such as flavor, smoothness, appearance, and provide stabilization. They are used in frozen desserts, icings, toppings and also to retard staling of bread. They are also used for drug delivery and for making skin creams and sunscreens. The current technique to produce pure monoglyceride cannot achieve more than 96% purity and may cause degradation of products. In this research a new technique has been developed that will be used to extract and fractionate high purity monoglycerides by using an environmentally-benign solvent, high pressure carbon dioxide. A high pressure gas, also called supercritical fluid, was used to extract monoglycerides from a mixture and to produce enriched product that is more than 97% pure. The described technology offers the end user (food, cosmetic and pharmaceutical companies) a non-polluting and versatile process with better potential than the current technique. The general public will also benefit since this technology has no adverse effects on the environment. Technical Abstract: Effects of temperature and pressure of supercritical CO2, and composition of the feed, on the extraction and fractionation of a mixture of monoacylglycerides (MAGs), diacylgylcerides (DAGs) and triacylglycerides (TAGs) were determined. Feedstock was extracted using supercritical CO2 flowing at 3 L/min with MAGs being rectified using a 2.4 m packed column kept under a longitudinal thermal gradient. The feed material approximated a commercial product used in the industrial enrichment of MAGs and was composed of 47.5 wt% MAG, 45.5 wt% DAG, and 5.7 wt% TAG having main acyl chain compositions of 9.8 wt% C16:0, 41.1 wt% C18:0 and 41.9 wt% C18:1 and 9.6 wt% C18:2. The transient composition profile of fractions was used to study the dynamic behavior of the semi-batch column fractionation. Effects of pressure and temperature gradient on separation selectivity and product yields were investigated. Fractionation of glycerides was affected by both their interactions with CO2 and respective vapor pressures enhancement. Fractions of MAGs, DAGs and TAGs exceeding 90% purity were produced sequentially. Increasing column pressure from 20.7 MPa to 34.4 MPa decreased extract MAGs concentration from 90+ wt% to 56 wt% and reduced separation selectivity from 11. to 1.3. Internal reflux induced by the temperature gradient was calculated to be 2.2 at 20.7 MPa, by measuring extraction rates for the column at 65 deg C and at a temperature gradient of 65 deg C to 95 deg C. Induced internal reflux increased separation selectivities at 20.7 MPa. |
