Supercritical fluid processing, food applications

Supercritical fluid (SCF) food processing plants have become one of the more robust technologies for new applications within the food industry in recent years. The announcement of the construction and start up of a coffee decaffeination plant in Houston, Texas (X) has markedly heightened interest, resulting in increased awareness of the unique factors that apply to the design of the SCF processing plant and, more importantly, the considerations necessary to select equipment and components for installation in a SCF processing plant. 

SFE has been used for a relatively long time on a large industrial scale and only recently on a smaller, laboratory scale. There are excellent reviews that cover the entire gamut of SFE applications (3,8). The often cited example is decaffeination of coffee. Other examples of natural products extraction in the food industry include extraction of hops, spices, flavors, and vegetable oils. Table 2 lists selected companies that are involved in supercritical fluid processes for natural products (24). 

Brunner, G., Supercritical fluids Technology and application to food processing, Journal of Food Engineering, 67,21-33,2005. 

Brunner G. Supercritical fluids technology and application to food processing. J Food Eng... 

Supercritical fluid extraction (SFE) has been widely used to the extraction processes in pharmaceutical industries. Besides application of SFE in phannaceuticals, it has been applied on a wide spectmm of natural products and food industries such as natural pesticides, antioxidants, vegetable oil, flavors, perfumes and etc [1-2]. 

Although the general principles of separation processes are applicable widely across the process industries, more specialised techniques are now being developed. Reference is made in Chapter 13 to the use of supercritical fluids, such as carbon dioxide, for the extraction of components from naturally produced materials in the food industry, and to the applications of aqueous two-phase systems of low interfacial tensions for the separation of the products from bioreactors, many of which will be degraded by the action of harsh organic solvents. In many cases, biochemical separations may involve separation processes of up to ten stages, possibly with each utilising a different technique. Very often, differences in both physical and chemical properties are utilised. Frequently... 

Polycyclic aromatic hydrocarbons (PAHs) have been extracted from contaminated land samples by supercritical fluid extraction jSFE) with both pure and modified carbon dioxide. Removing an analyte from a matrix using SFE requires knowledge about die solubility of the solute, the rate of transfer of the solute from the solid to the solvent phase, and interaction of the solvent phase with the matrix. These faclors collectively control the effectiveness of the SFF process, if not of the extraction process in general. The range of samples for which SFE has been applied continues to broaden. Applications have been in the environment, food, and polymers. 

In recent years, supercritical fluid extraction has received widespread attention for the removal of non- or low-volatile organic components from liquid and solid matrices. This process has many potential applications like analytical extractions, applications in the food and drug industry, activated carbon regeneration or soil remediation. 

Supercritical fluid technology has been widely used in extraction and purification processes in the food and pharmaceuticals industryPl 1 1 and for techniques such as supercritical fluid chromatography. Recently, there has been a significant increase in interest of the use of sub- as well as supercritical (SC) carbon dioxide as a substitute for chlorofluorocarbons (CFCs) for a variety of specific and specialized applications t in which the choices of enviromnentally acceptable alternatives are quite limited. 

Supercritical fluid extraction offers several advantages over conventional extraction processes. The extraction is carried out at high pressures and then the extract is usually recovered by lowering the pressure, as the solubility is a strong function of fluid pressure. The compositions of the extracts are different from those from the liquid extraction. Supercritical fluid extraction has been well accepted for coffee decaffeination and is being applied in other food, cosmetics, and pharmaceutical applications. Supercritical carbon dioxide is an environmentally benign nonflammable fluid. 

SCCO2 is largely used to process food (extraction or fractionation), but other applications, such as the fluoropolymer synthesis by DuPont, hydrogenation or alkylation by Thomas Swan, coatings by Union Carbide, and polyurethane processing by Crain Industries, are still in development [111]. The application of supercritical fluids (SCFs) as reaction media with homogeneous catalysts has been mainly investigated on a laboratory scale. 

---