## 3 Non-Thermal Technologies in Winemaking Process
### Pulsed Electric Field (PEF) Effects on Microbial Populations, Phenolic Extraction, and Wine Quality
The authors applied PEF treatments of low (35 kJ/kg, 65 \(\upmu\)s) and high (97 kJ/kg, 177 \(\upmu\)s) intensity at 15 kV/cm in combination with different doses of SO\({}_{2}\) (0, 5 and 20 mg/L), and found that even the least intense PEF treatment was efficient in obtaining _S. cerevisiae_ var. _bayanus_ CHP yeast-free wine during the storage period without added SO\({}_{2}\). In addition, the synergistic effect of combined PEF (10-25 kV/cm, 25-1000 \(\upmu\)s, 40-170 kJ/kg) and SO\({}_{2}\) (10, 25 and 50 mg/L) treatments on the inactivation of _S. bayanus_ and _B. bruxellensis_ in red wine was also studied by [PERSON] et al. [45]. The authors reported the significant inactivation (>4.0 log cycles) of both yeast types right after applying the less intense PEF treatment (10 kV/cm, 115 kJ/kg). After 24 h of incubation among the treated yeasts, moderate PEF treatment (15 kV/cm, <100 kJ/kg) alone and the ones combined with SO\({}_{2}\) treatment demonstrated efficient lethal effect on both yeasts. In a study by [PERSON] et al. [50], the authors examined the effects of PEF parameters (electric field strength, outlet temperature, and specific energy), _B. bruxellensis_ yeast strain, and alcohol content on _B. bruxellensis_ inactivation in Cabernet Sauvignon red wine. Among the processing parameters, the electric field strength had a higher effect on _B. bruxellensis_ inactivation than specific energy, resulting in 1.0, 2.1, and 3.0 log reductions when using PEF at 31, 40, and 50 kV/cm. Furthermore, an increase in outlet temperature of 10 \({}^{\circ}\)C at 50 kV/cm resulted in the double inactivation of 3.0 log CFU/mL. Other factors such as yeast strain and alcohol content also showed a significant influence on PEF inactivation. Moreover, PEF processing did not lead to the dangerous dissolution of metal ions (Fe, Cr, Ni) in wine. Recently, [PERSON] [43] showed that PEF with increased applied energy (2.4-13.2 kJ) resulted in significant inactivation of all yeasts (_S. cerevisiae, H. anomola, C. lipolytica_) and bacteria (_L. delbrueckii_ ssp. _bulgaricus, E. coli_) in red wine with a greater increase in pH value, conductivity, color parameters (L* and b*), and total phenolic substance content with no remarkable change in the concentration of metal ions. Additionally, 13.2 kJ PEF treatment induced significant changes in the sensory characteristics of wine. On the other hand, [PERSON] et al. [29] exposed five different table wines to PEF at an electric field strength of 45 kV/cm and frequency of 800 Hz and found that PEF had no effect on the total phenols, antioxidant activity (except for a decrease in Syrah red wine), and pH value, while it increased the color density in red and white wines directly after processing. After 2 months, authors observed similar patterns in the quality characteristics of most treated wines. [PERSON] et al. [57] applied two continuous PEF treatments, first to crushed red grapes (5 kV/cm) to increase the extraction of phenolic compounds and color, and second to the must after 24 h maceration (17.5 kV/cm) to reduce the wild microbial population and improve the implantation of non-_Saccharomyces_ yeasts. PEF processing of grapes resulted in increased color intensity, total phenol index, and anthocyanin and tannin content in produced musts, while pH, \({}^{\circ}\)Brix, and the total acidity were not affected. In addition, successful reduction in wild yeasts (up to 2 log CFU/mL) was achieved after a second PEF treatment of higher intensity. Consequently, PEF allowed for selected non-_Saccharomyces_ yeasts to better implant in obtained red musts and generate more desired metabolites in wines, resulting in more total esters and anthocyanins, especially vitisin A. The overall sensory perception of wines with PEF was described as more complex, with higher intensity of some attributes such as aroma intensity, fruit, and acidity. A similar trend was observed in a study from [PERSON] et al.