Researchers of Wageningen University and Research Centre in the Netherlandshave developed a new clean, process to isolate valuable or undesired componentsfrom solids, such as components for food products. In contrast to other conventionalprocesses, the new invention concerns a continuous process that can be controlledeasily and secondly, leads to higher extraction yields. At the 15th of Junethe researchers have presented their new technology at a conference in Triestin Italy.
Many odours and flavours are extracted from plant tissues by dissolving inorganic solvents, such as hexane and alcohols. Subsequently, the solventis evaporated after which the target components remain as pure product. Froman environmental point of view and regarding food safety, the use of organicsolvents is not always desired.In the new process, which is developed in the framework of an EuropeanUnion project C-REX, carbon dioxide is used as a solvent. In this processthe carbon dioxide is compressed extensively, which gives it propertiesthat are comparable to both solid and liquid, i.e. the so-called supercriticalphase. The application of compressed carbon dioxide instead of organicsolvents results in a cleaner extraction process. Carbon dioxide is a gasthat is abundantly available in the atmosphere.
Some industries already apply compressed carbon dioxide to remove, forexample, caffeine out of coffee or to extract flavours from hops for theproduction of beer. The Dutch researchers of Agrotechnology & FoodInnovations, part of Wageningen UR, are the first to make this a continuousprocess. As a result, the separation process is strongly simplified. Besidesthat, in relation to other methods, the yields can be much higher, whichleads to lower energy consumption and carbon dioxide loss and also, toreduction of processing costs.
In the new, continuous process an extruder is implemented. This machine,which can be roughly described as two rotating screws in a metal tube,is normally used for mixing and shaping of plastics and food products.The Dutch researchers have adapted the machine in such a way that it canbe employed as a high-pressure vessel in which the continuous extractioncan take place. The high pressure is maintained by creating two materialplugs in the beginning and end of the extruder. In between, the compressedcarbon dioxide is added, taking up the desired (or undesired) components.Next, the researchers separate the dissolved product from the carbon dioxideby decreasing the pressure after which the carbon dioxide is re-used andthe pure product remains as solid or liquid.
The developed process can also be applied for the purification of materials,such as plastics. Next to that, the new technology can be utilised asa new production route for foams in the plastic and the food industry.
NOTE FOR THE EDITOR
More information can be obtained from Frank Giezen (Agrotechnology & FoodInnovations bv, Wageningen UR), tel. +31 317 477561, e-mail frank.giezen@wur.nl.See also www.agrotechnologyandfood.wur.nl. General information on WageningenUniversity and Research Centre (Wageningen UR) at www.wur.nl/uk.