Supercritical and Liquid CO2 Extraction of Fat From Rendered Materials

The processing of rendered materials (RM) allows the separation of fat which results in value-added co-products for energy and up-graded feed sources for animals. The current industry utilizes steam and continuous mechanical presses to extract the fat from the RM. The main objective of this work is to investigate the use of CO₂ as a solvent for the extraction of the remaining triglyceride and fatty acid components from the RM.  This will result in ecological and economic benefits for the rendering industry.

Supercritical and liquid CO₂ were employed for the extraction of fat from RM. The lipids were characterized by gas chromatography and by alkaline titration to determine the fatty acids (FA) composition and the amount of free FA, respectively. A continuous-flow extraction unit was used to analyze the impact of pressure, temperature, and mass of CO₂ on fat extraction yield. A cost-benefit analysis will be performed for the produced materials in order to determine the feasibility of the systems. The mass of CO₂ and pressure had the greatest effects on the yield. The highest extraction yield was 91% using only 40g of CO₂ per 1g of sample at 3000 psi. The rest of the fat (1% in the RM) was determined to be insoluble at all conditions.  The FA composition is expected to vary depending on the operating conditions and the FFA to remain constant.  It can be concluded that the extraction of fat by means of CO₂ can be successfully achieved with high yields by a continuous-flow configuration.