**7. The SCF application as dispersion for biocatalysis**

The advantage of using enzymes in the SCF include; completion of synthesis reactions in which water is a product, the increased solubilities of hydrophobic materials, greater thermo-stability of biomolecules, readily solvent recycling, integrated biochemical reactions,

typical hard cheeses from "raw milk". With this process it could be possible to reduce the overall microbial load adverse to making cheese without modifying the subtle chemicophysical balance of milk. As pressure-treated milk shows modified properties during further processing, such as changed rennet or acid coagulation characteristics, coagulation time, and gel firmness. Further studies should be carried out to understand whether the structural changes of milk compounds could worsen cheese-making processes (Cuoghi, 1993). Also, the effect of high pressure on microorganisms and enzymes of ripening cheeses were studied. A significant decrease of total microbial count was obtained at the pressure above 400MPa. It was found that the inactivation of microorganisms was affected more by their initial number than by the type of cheese and its maturity. *E. coli* was completely inactivated in 400 MPa pressurized cheeses irrespective of their initial count. *Enterococci*  were inactivated at 400 MPa, while the pressure of 600 MPa was needed to achieve this effect in a 2-week-old cheese. Yeasts and moulds were inactivated with 200 MPa. Aminopeptidases and endopeptidases of both cheese and its extract lost the catalytic abilities at 600 MPa irrespective of the type and ripening time of cheeses (Reps et al., 1994). On the whole, the SCF sterilization has been reported as a successful approach in the sterilization of several kinds of food including; fruits, juices, vegetables, jam, meat, milk, wine, liquid whole egg, natural pigments, yoghurt, and even chocolate (Hammam, 1992).

**5. The use of semi-preparative SCF chromatography for the separation and** 

Many successful applications of this technique for the analysis of triglycerides in butter fat and fish oil have been described. The coupling of SFC with thin layer chromatography resulted in a powerful method for identification of trace substances such as phenolic

• *Debittering of citrus juices*. Kimball (1987) use SC-CO2 to extract bitter triterpenoids, such as limonin from orange juice in which the pressure increase from 2.14 to 4.28 MPa was effective on limonin reduction. A change in the final pH, vitamin C, pulp content,

• *Extracting and /or concentration of citrus essential oils*. Mira et al. reported that it was possible to concentrate the flavor portion of citrus oils with SC-CO2 at 70°C and 83 MPa. These conditions were optimum forminimizing the amount of flavors lost in extraction,

• *Effect on quality attributes and microorganisms*. The prevention of undesirable flavors caused by microorganisms growing under low pH conditions is important. Therefore, the SC-CO2 treatment of orange juice had the added benefit of reducing microbial

The advantage of using enzymes in the SCF include; completion of synthesis reactions in which water is a product, the increased solubilities of hydrophobic materials, greater thermo-stability of biomolecules, readily solvent recycling, integrated biochemical reactions,

**isolation of flavor and food constitutes** 

**6. The application of sc-co2 in citrus processing** 

amino acids, and percentage of acid could not be detected.

which also resulted in low extraction yields (Mira et al., 1999).

**7. The SCF application as dispersion for biocatalysis** 

antioxidants (Flament et al., 1994).

numbers.

and separations. Enzymes such as alpha amylase, glucose oxidase, lipase, and catalase retained their activities in the solution of high pressure CO2 in water. All thermal and nonthermal methods to stabilize could have their own disadvantages. So, the researchers have focused on the applicability of SC in this process (Nakamura, 1990). Soybean lipoxygenase dissolved in Tris HCl buffer (0.01M; pH 9) was irreversibly inactivated by combined pressure (up to 650 MPa) and low temperature (−15 up to 35°C) treatment. The enzyme inactivation followed a first order reaction and the phase transition of water did not change the kinetic inactivation behavior.
