Food industry applications supercritical

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... 

Food Applications, Carbon dioxide, a nontoxic material, can be used to extract thermally labile food components at near-ambient temperatures. The food product is thus not contaminated with residual solvent, as is potentially the case when using conventional liquid solvents such as methylene chloride or hexane. In the food industry, C02 is not recorded as a foreign substance or additive. Supercritical solvents not only can remove oils, caffeine, or cholesterol from food substrates, but can also be used to fractionate mixtures such as glycerides and vegetable oils into numerous components. 

Critical temperatures of substances vary over a wide range, allowing for SCF selection for specific applications. Supercritical CO2 is especially useful in the food and pharmaceutical industries where toxicity of the extraction medium, solvent entrapment, and thermal stability of materials are concerns. Specifically, SCFs required for processing thermally labile compounds such as proteins and peptides should have a critical temperature that is close to ambient conditions (e.g., CO2 and ethylene with critical temperatures of 31.1°C and 9.3°C, respectively). 

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. 

An excellent review or LLE applications in the food industry is given by Hamm,17 Since solvent toxicity is a major consideration, supercritical solvents, such as CO, which are nomoxic and LLE from an aqueous leachate are two popalar means of deriling with this problem. Figure 7.8-11 is a cooceptual supercritical extraction flowsheet. Because Tc is much lower than either 7 or rB, the solvent (e.g., C02) simply is flashed from the solute by throttling (an isenthalpic process). Then the vapors are compressed (an isentropic process) and cooled (an isobaric step) to complete the solveni recycle. Usually, costs are determined by the compressor requirearerUs. Several potential applications of supercritical or near-critical solvents are discussed in more datail else where,... 

Some of the areas in which supercritical CO2 (SCCO2) is commercially important are summarized in Figure 8.9. Extraction processes in the food, tobacco (nicotine extraction) and pharmaceutical industries dominate. Supercritical CO2 is a selective extracting agent for caffeine, and its use in the decaffeination of coffee and tea was the first commercial application of a supercritical fluid, followed by the extraction of hops in the brewing industry. Solvent extractions can be carried out by batch processes, or by a continuous process in which the CO2 is recycled as shown schematically below ... 

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). 

Supercritical extraction (SCE) is a modem separation technique that uses the dramatic increase in solubility of some solutes in supercritical fluids. Important applications have been found in food industry, as the extraction of caffeine from coffee, fats from butter, etc. Ethanol may be also recovered by extraction with COj. We should also mention the use of supercritical water to solve environmental problems, as the destmction of poly-chloro-benzenes (PCBs) by oxidation in supercritical water. 

Capillary Supercritical Fluid Chromatography with Applications in the Food Industry... 

Due to its unique characteristics, carbon dioxide is the only supercritical fluid used in food industry. Research and development in this area has been prolific since the extraction of caffeine was patented in 1964 [13], After its practical application in Germany in 1978 (by the Hag AG Corporation), commercial plants have been constructed [3,14,15] for extracting ... 

The oldest commercially used SCCO2 extraction process is the decaffeination of coffee beans. This is still the most profitable application of SCCO2, but supercritical fluids have been tested in the food industry, pharmaceutical industry, textile dyeing, impregnation, polymer synthesis and processing, dry cleaning, etc. ... 

K. Nagahama, in Handbook of Supercritical Fluids. Application in Food Industries (in Japanese) (K. Nagahama and I. Suzuki, eds.), p. 18, Science Forum, Tokyo, Japan, 2002. 

While research employing SFC is still in the physico-chemical and operational stages, the evolution of the technique is rapidly progressing (303-305). Commercial instruments are now available, but the application of SFC to research problems is still uncommon. One area that is particularly promising is the application of SFC for assaying compounds that are extracted industrially by supercritical fluids. For example, SFC can be used as an analytical tool to quantitate caffeine (114), the oligomer content of polymerizations (111), and fats and oils in foods or petrochemical products (316). 

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