Bernhard Seifried

Bioseparation of Nutraceuticals Using Supercritical Carbon Dioxide

Use of supercritical carbon dioxide (SC–CO2) for the extraction and fractionation of nutraceuticals offers numerous advantages, avoiding the use of organic solvents and minimizing the degradation of bioactives. Optimal design of such processes requires fundamental knowledge of not only the solubility behavior but also physical and transport properties of the SC–CO2 + nutraceutical mixture under high pressure. Determination of such fundamental data is challenging and requires specialized equipment. Because of the nonpolar nature of SC–CO2, lipid-based nutraceuticals, including specialty oils and carotenoids, can be extracted with neat SC–CO2; however, recovery of phytochemicals like phenolics require the addition of a polar cosolvent. Ethanol is the cosolvent of choice for nutraceutical applications. Extraction of nutraceuticals from a large number of plant materials has been studied extensively for the optimization of various processing parameters. Further fractionation of the extracts or various other mixtures is possible using fractional extraction, fractional separation, or column separation approaches to obtain bioactives in concentrated form. Supercritical fluid technology offers the flexibility to extract and fractionate nutraceuticals by combining different techniques and simplifying the overall process compared to conventional technologies, but feasibility of every application needs to be evaluated on a case-by-case basis. Some applications such as the extraction of specialty oils and recovery of tocopherols from deodorizer distillate have already reached commercialization level while numerous other promising applications are under development around the world.

Design of a high-pressure circulating pump for viscous liquids.

The design of a reciprocating dual action piston pump capable of circulating viscous fluids at pressures of up to 34 MPa (5000 psi) and temperatures up to 80 degrees C is described. The piston of this pump is driven by a pair of solenoids energized alternatively by a 12 V direct current power supply controlled by an electronic controller facilitating continuously adjustable flow rates. The body of this seal-less pump is constructed using off-the-shelf parts eliminating the need for custom made parts. Both the electronic controller and the pump can be assembled relatively easily. Pump performance has been evaluated at room temperature (22 degrees C) and atmospheric pressure using liquids with low and moderately high viscosities, such as ethanol and corn oil, respectively. At ambient conditions, the pump delivered continuous flow of ethanol and corn oil at a flow rate of up to 170 and 17 cm3/min, respectively. For pumping viscous fluids comparable to corn oil, an optimum reciprocation frequency was ascertained to maximize flow rate. For low viscosity liquids such as ethanol, a linear relationship between the flow rate and reciprocation frequency was determined up to the maximum reciprocation frequency of the pump. Since its fabrication, the pump has been used in our laboratory for circulating triglycerides in contact with supercritical carbon dioxide at pressures of up to 25 MPa (3600 psi) and temperatures up to 70 degrees C on a daily basis for a total of more than 1500 h of operation functioning trouble free.

Characterization of oat beta-glucan and coenzyme Q10-loaded beta-glucan powders generated by the pressurized gas-expanded liquid (PGX) technology

The physicochemical properties of the oat beta-glucan powder (BG) and coenzyme Q10 (CoQ10)-loaded BG powder (L-BG) produced by the pressurized gas-expanded liquid (PGX) technology were studied. Helium ion microscope, differential scanning calorimeter, X-ray diffractometer, AutoSorb iQ and rheometer were used to determine the particle morphology, thermal properties, crystallinity, surface area and viscosity, respectively. Both BG (7.7μm) and L-BG (6.1μm) were produced as micrometer-scale particles, while CoQ10 nanoparticles (92nm) were adsorbed on the porous structure of L-BG. CoQ10 was successfully loaded onto BG using the PGX process via adsorptive precipitation mainly in its amorphous form. Viscosity of BG and L-BG solutions (0.15%, 0.2%, 0.3% w/v) displayed Newtonian behavior with increasing shear rate but decreased with temperature. Detailed characterization of the physicochemical properties of combination ingredients like L-BG will lead to the development of novel functional food and natural health product applications.