Influence of pulsed electric field on the content of polyphenolic compounds in wine

Grapes (Marechal Foch varieties) were subjected to the pulsed electric field (PEF) for 10 s, at a frequency of 20 pulses per second and two values of electrical field strength: 3.3 kV/cm and 5 kV/cm. Then grape fermentation was carried out according to the procedures used in the wine industry for 8 weeks. In the obtained wines, the total polyphenolic compounds were determined (they were converted into gallic acid equivalent (GAE) per 1 dm ³ wine (GAmg/dm3). The total content of polyphenolic compounds in the obtained wines is from 897 (WMF P1) to 997 (WMF P3) GAmg/dm ³. As it results from the study the pulsed electric field has a positive influence on the polyphenol content in obtained wine. The usage of a pulsed electric field in pre-treatment of grapes results in increasing the polyphenol content by 10% during the extraction and fermentation process. No significant influence of the applied intensity was found (3.3 kV/cm, 5 kV/cm) on the polyphenol content. The obtained results indicate a higher efficiency of extraction of antioxidants from grapes under the influence of PEF. Because polyphenolic compounds are health-promoting then higher content of them is beneficial for people. Moreover, they affect the more intense wine colour.