14A-20

Effect of water on canola oil hydrolysis in an on-line extraction-reaction system using supercritical CO2

J. L. MARTINEZ, University Simon Rodriguez, Valencia, Venezuela, K. Rezaei, Department of Agriculture, Food and Nutritional Science, University of Alberta, #410 - Agriculture Centre, Edmonton, AB T6G 2P5, Canada, and F. Temelli, Department of Agricultural, Food and Nutritional Sciences, University of Alberta, #410 - Agriculture Centre, Dept. AFNS, University of Alberta, Edmonton, AB T6G 2P5, Canada.

JUSTIFICATION:

Conducting enzymatic reactions in supercritical CO₂ (SCCO₂) medium has gained increasing attention due to the higher conversion rates and ease of separation of products. An appropriate water level is essential for maintaining the catalytic activity of the enzymes. Also, water is one of the substrates in the hydrolysis reactions. Therefore, selecting an optimum water level is important for such reactions especially when conducted in SCCO₂, since some water is lost with the flow of SCCO₂.

OBJECTIVES:

To determine the effect of the amount of water on the continuous enzymatic hydrolysis of canola oil in an on-line extraction-reaction process in SCCO₂.

METHODS:

A laboratory-scale on-line extraction-reaction system, where extraction and reaction were performed in two separate chambers, was used. Canola flakes (3.0 g) were loaded into the extraction cell. Water (0.002-0.05 mL/min) was continuously pumped into the oil-laden SCCO₂ before introduction to the reactor. Immobilized lipase from Mucor miehei (Liposyme IM) was used as a catalyst. Pressure and temperature of 24 MPa and 35° C, respectively, and CO₂ flow rate of 0.5 L/min (measured at ambient conditions) were applied throughout all experiments for 6 h. Supercritical fluid chromatography was used to analyze the reaction products consisting of free fatty acids (FFA), mono-, di- and triglycerides.

RESULTS:

Maximum conversion rate was obtained at a water flow rate of 0.002 mL/min, where 97% (mole fraction) FFA content was achieved in the product mixture, i.e. almost a full hydrolysis. A small amount of diglycerides detected only at the beginning of the run along with the absence of monoglycerides verified this conclusion. Conversion rate dropped with an increase in the water flow rate.

SIGNIFICANCE:

Water content is an important factor in optimizing the enzymatic hydrolysis of canola oil in SCCO₂. By controlling this factor, a full enzymatic hydrolysis of triglycerides in SCCO₂ can be performed leading to a pure FFA. On-line extraction-reaction of canola oil using SCCO₂ shows potential for process development for conversion to high-value products with minimal thermal degradation and elimination of organic solvent use.