Impact of Electric Pulse Treatment on Selective Extraction of Intracellular Compounds from Saccharomyces cerevisiae Yeasts

Treatments by high-voltage electrical discharges (HVED, needle-plate electrode geometry, U = 40 kV, t (p) a parts per thousand aEuro parts per thousand 0.5 mu s) and pulsed electric field (PEF, plate-plate electrode geometry, E = 5-40 kV/cm, t (p) a parts per thousand aEuro parts per thousand 8.3 mu s) were evaluated as tools for selective extraction of different intracellular components from the wine Saccharomyces cerevisiae (bayanus) yeasts in a 0.5% (w/w) aqueous suspension. The pulses in the form of damped oscillations and exponential decay were applied in HVED and PEF modes of treatment, respectively. The extraction efficiency results obtained using HVED and PEF techniques were compared with those for high-pressure homogenization technique. The HVED and PEF treatments always resulted in incomplete damage of yeast cells, though efficiency of HVED was higher than that of PEF. The high selectivity of extraction of ionic substances, proteins, and nucleic acids was demonstrated; e.g., electric pulse treatments at E = 40 kV/cm and N = 500 allowed extraction of a parts per thousand 80% and a parts per thousand 70% of ionic substances, a parts per thousand 4% and a parts per thousand 1% of proteins and a parts per thousand 30% and a parts per thousand 16% of nucleic acids in cases of HVED and PEF modes, respectively.