title: Extraction of polyphenols from black tea--conventional and ultrasound assisted extraction.
abstract: Products from plant raw materials gain increasing importance in food-, cosmetics and pharmaceutical industry. By way of contrast, due to lack of detailed physico-chemical fundamentals, existing production processes are economically not optimal designed. This leads to a need for deeper understanding of the processes and furthermore a systematic process and equipment design for the potentially applicable extraction techniques. Using the example of polyphenol extraction from black tea (Kenya), the conventional and ultrasound assisted extractions are investigated. Here, the state of the art as well as a comparison between the two techniques is in focus. Especially, resulting quasi-equilibria and mass transport kinetics serves as a criteria. The physico-chemical background is discussed taking particle size distributions and scanning electron microscope (SEM) measurements into account. Conclusively, process alternatives are projected and discussed. Hence, the present study makes influences of ultrasound technique on physico-chemical characteristics during extraction a subject of discussion.
authors: Institute for Separation and Process Technology, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany.
authors: Simon
authors: S
authors: Both
authors: Université d'Avignon et des Pays de Vaucluse, INRA, UMR 408, GREEN Extraction Team, F-84000 Avignon, France.
authors: Farid
authors: F
authors: Chemat
authors: Institute for Separation and Process Technology, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany. Electronic address: strube@itv.tu-clausthal.de.
authors: Jochen
authors: J
authors: Strube
mesh_terms: D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods*; D055598:Chemical Phenomena; D007700:Kinetics; D010316:Particle Size; D059808:Polyphenols / Q000737:chemistry / Q000302:isolation & purification*; D013662:Tea / Q000737:chemistry*; D014465:Ultrasonics / Q000295:instrumentation / Q000379:methods*
chemical_list: D059808:Polyphenols; D013662:Tea
keywords: Black tea; Extraction; Maceration; SEM; Ultrasound