chapter  7
28 Pages

Supercritical Fluid Extraction in Food Processing

The regulatory legislations on advocating a reduction in the use of organic solvents that are harmful to the environment led to the introduction of alternative methods by the food industry to produce relatively pure ingredients without causing adverse environmental impact (Sahena et al. 2009). Supercritical ªuid extraction (SFE) using carbon dioxide (CO2) as a solvent has provided an excellent alternative to conventional solvent extraction and mechanical pressing since it offers several advantages, including a lack of solvent residue and better retention of aromatic compounds (Zaidul et al. 2007a; Norulaini et al. 2009). Supercritical CO2 has the unique ability to penetrate through solids like a gas, and dissolve materials like a liquid. Additionally, it can readily change in density upon minor changes in temperature or pressure. A supercritical ªuid is any substance at a temperature and pressure above its thermodynamic critical point. Mass transport properties, such as ªuid and analyte diffusion coef™cients, are greater in supercritical ªuid media, resulting in faster extraction ªuxes and a substantial reduction in extraction time (Sahena et al. 2009). Supercritical ªuids possess both gas-like and liquid-like qualities, and the dual role of such ªuids provide ideal conditions for extracting compounds with a high degree of recovery in a short time. The critical temperature (°C) and critical pressure (MPa) of solvents commonly used as supercritical ªuids are given in Table 7.1.

7.1 Introduction .................................................................................................. 195 7.2 Principles and Current Instrumentation Trends ........................................... 197 7.3 Fractionation of Fats ..................................................................................... 201 7.4 Determination of Vitamins ...........................................................................207 7.5 Extraction of Antioxidants ............................................................................209 7.6 Extraction of Volatiles/Flavors ..................................................................... 212 7.7 Determination of Pesticide and Drug Residues ............................................ 215 7.8 Conclusions ................................................................................................... 215 References .............................................................................................................. 216

Because of its low critical constants, low cost, nontoxicity, chemical inertness, and nonªammability, CO2 is used as a common solvent in the food industry (Rozzi and Singh 2002). The absence of surface tension allows the rapid penetration of supercritical carbon dioxide (SC-CO2) into the pores of heterogeneous matrices and helps to enhance extraction ef™ciencies (Lang and Wai 2001). The nontoxicity and easily separable nature of CO2 are extremely important for application of SFE technology in the food processing industry.