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Stimulation of Saccharomyces cerevisiae Cultures by Pulsed Electric Fields

Mattar, Jessy R., Turk, Mohammad F., Nonus, Maurice, Lebovka, Nikolai I., El Zakhem, Henri, Vorobiev, Eugene
Food and bioprocess technology 2014 v.7 no.11 pp. 3328-3335
Saccharomyces cerevisiae, bioactive properties, cell membranes, electric field, electroporation, fermentation, nutrients, pulsed electric fields, viability, yeasts
The effects of stimulation of Saccharomyces cerevisiae cells in an aqueous suspension by pulsed electric field (PEF) with electric field strength E = 20–2,000 V cm⁻¹ and effective PEF treatment time t PEF = 10⁻⁵–1 s were investigated. At relatively high electric field strengths (E > 1,000 V cm⁻¹) and moderate times of PEF treatment (t PEF > 100 μs), the extraction of ionic components from yeast was observed, which can be related to electroporation of cell membranes. Petri dishes counting revealed dependency of the colony sizes on the time of preliminary fermentation t f and power consumption W. The “logarithmic” and “saturated” types of electrostimulation were distinguished. At “logarithmic” electrostimulation (10⁻⁷ J mL⁻¹ < W < 10⁻¹ J mL⁻¹), the viability of yeast cells increased with the increase of power consumption and was higher for longer fermentation (t f = 24 h). However, at “saturated” electrostimulation (10⁻¹ J mL⁻¹ < W < 10¹ J mL⁻¹), the viability of yeast cells was noticeably higher for t f = 1 h than for t f = 24 h. The impact of preliminary fermentation time and PEF protocol on biological activity of cells and consumption of nutrients was also discussed.