chapter  5
28 Pages

Pulsed Electrical Discharges: Principles and Application to Extraction of Biocompounds

Treatment of aqueous systems by a strong electric ™eld has been studied for many years because of its importance for many practical applications in biology, chemistry, and electrochemistry. In particular, the method of pulsed electrical discharges

5.1 Introduction .................................................................................................. 145 5.2 Principles and Mechanisms of Electrical Discharges in Water .................... 146

5.2.1 Propagation of PCED ....................................................................... 148 5.2.2 Physical and Mechanical Effects of PAED ...................................... 149 5.2.3 Characterization of Shock Waves Associated with PAED ............... 151 5.2.4 Application of PAED to Extraction of Various Biocompounds ...... 152 5.2.5 Extraction of Proteins from Wine Yeast ........................................... 153 5.2.6 Extraction of Total Soluble Matter from Fennel ............................... 155 5.2.7 Extraction of Glycosides from Stevia Leaves ................................... 156 5.2.8 Extraction of Oil from Linseeds ....................................................... 157 5.2.9 Electrically Assisted Aqueous Extraction of Polyphenols ............... 158

5.2.9.1 Extraction of Polyphenols from Grape Pomace ................. 159 5.2.9.2 Extraction of Polyphenols from Grape Skins .................... 160

5.2.10 Hydroethanolic Extraction Assisted by PAED ................................. 163 5.2.11 Application of PAED at the Semipilot Scale .................................... 164 5.2.12 Effect of the Secondary Reactions Produced by PAED .................. 165

5.3 Future Research Needs ................................................................................. 168 References .............................................................................................................. 168

(PED) was developed for enhancing extraction of biocompounds. The general issues and questions regarding the role of electrical discharge processes in extraction of biocompounds include the following:

1. What are the fundamental reaction mechanisms and breakdown pathways of electrical discharge in water? How are electrical discharges initiated and how do they propagate from one electrode to another? What are the main chemical effects of the extreme electromagnetic and mechanical conditions induced by PED in the bulk of solution that inªuence cell disruption?