Alternatives to Conventional Food Processing
Chapter 3: Advances in Critical Fluid Processing
Published:16 Dec 2010
Critical fluids have been historically applied as an extraction and/or reaction medium in the food, agricultural and nutraceutical industries. The solution thermodynamic properties of solvents such as water above its boiling point and under pressure, also known as “subcritical water”, is now being commonly employed as an option for the extraction of some polar components such as flavonoids and carbohydrates from natural products. This chapter discusses the application of subcritical fluids in extraction, reaction and/or hydrolysis of value-added products from food and agricultural matrices. Further, we discuss the option of coupling a relatively “polar” subcritical solvent such as water with a “non-polar” supercritical fluid such as carbon dioxide and utilize them in different unit processing modes. Carbonic acid is a “natural” catalyst which allows the pH to be controlled within certain limits and can aid in the extraction of natural products, a replacement for mineral acid catalysts in hydrolysis reactions and in microbial deactivation. Enhanced mass transfer of pressurized fluids through the feed matrix can also be achieved by tandem processing using expellers or extruders. Such processes are now being applied for the extraction of seed oil from matrices. Along with the documented success of SFE using SC-CO2, these additional processing options can accelerate an “all green” sustainable technology platform.