Experimental free amino acids selective extraction by supercritical carbon dioxide: modelling and optimization

A supercritical fluid extraction (SFE) method has been investigated to find the optimal conditions for selectively extracting free amino acids using carbon dioxide. This study examined three variables: temperature, pressure, and time. It was found that the SFE can selectively extract Alanine, Glycine, Cysteine, Histidine, and glutamic acid depending on the temperature and pressure of the extraction vessel. However, SFE showed a low extraction performance for other amino acids in the operating range studied. A design Expert was employed to generate a statistical model using the experimental data. The final optimization obtained the highest degree of selectivity for glutamic acid (P = 14 MPa T = 20 º C t = 40 min), Glycine (P = 12 MPa T = 60 º C t = 40 min), Histidine (P = 20 MPa T = 60 º C t = 20 min), Alanine and serine (P = 20 MPa T = 60 º C t = 60 min). This condition can be used to selectively extract each amino acid studied due to the striking difference between the optimal operating conditions of each category.