(Fig. 1a). Only electrodes in the treatment cell were
changed: a stainless steel needle electrode of 10 mm in diameter
and a grounded stainless plate electrode of 35 mm in diameter
were used. A positive pulse voltage was applied to the needle
electrode. The distance between the electrodes was 5 mm. Previous
results have shown that the optimal distance between electrodes
was 5 mm for polyphenols extraction (unpublished work). The
peak pulse voltage (U) was 40 kV.