## 3 Non-Thermal Technologies in Winemaking Process
### Pulsed Electric Field (PEF) Effects on Microbial Populations, Phenolic Extraction, and Wine Quality
[55] where early-harvested Sangiovese red grapes were subjected to pre-fermentative PEF treatments (0.9-3 kV/cm, 10.4-32.5 kJ/kg) to enhance the extraction of phenolic compounds and to maximize the color quality in musts and wines. Applied PEF treatments coupled to maceration processes resulted in musts and wines with increased total polyphenol content (49.0-60.8% and 22.7-37.1%) and color intensity (39-51% and max. 13.8%). Moreover, [PERSON] et al. [58] applied high-intensity PEF pretreatment followed by 4 days of cold maceration to Merlot red grapes, and also found an increase in a wide variety of anthocyanins and color intensity in grape musts. In addition, a similar PEF experiment was conducted on aroma compounds at different stages of winemaking [59]. Except for the increased content of anthocyanins, stilbenes, and hydroxycinnamic and hydroxybenzoic acids, Merlot wines produced with PEF-treated grapes (>40 kV/cm) showed higher blackcurrant flavor and odor. Recently, [PERSON] et al. [54] reported on the enhanced extraction of total stilbenes from the Graciano, Tempranillo, and Grenache grape varieties by PEF (7.4 kV/cm, 400 Hz, 20 us), while increased content of aroma and nitrogen compounds was only found in PEF-treated Grenache grape must. Similarly, this was found for stilbenes of the Graciano variety in a study by [PERSON] et al. [51]. Except for the improved extraction of valuable grape compounds, the benefit of PEF grape pretreatments was in reducing the maceration time from 6 to 3 days [52], or even 24 h [53], for the Grenache variety. Another study by [PERSON] et al. [49] reported that the initial microbial population in grape musts was reduced by 1 log CFU/mL with continuous PEF treatment (20 kV/cm, 150 pulses, 3 us). A high viability of inoculated non-_Saccharomyces_ yeasts was also maintained at the end of fermentation. Additionally, PEF-treated musts had a higher amount of some yeast metabolites, primarily esters, due to better implantation of the selected yeasts. Furthermore, [PERSON] et al. [42] conducted a pilot plant-scale study, using PEF (240 L/h, 4 bar) of 15 kV/cm and 35 kJ/kg for inactivation of _B. bruxellensis_ and other spoilage yeasts, and to evaluate its impact on the physicochemical and sensory characteristics of red wine. After PEF treatment, _B. bruxellensis_ was not detected in wine (detection limit of <150 viable cells/mL), while total yeast count showed a reduction of 80.66%. A slight but significant increase was observed in anthocyanins, total phenols, color intensity, and turbidity, while sensory characteristics of treated wine were not affected. Another pilot-scale study was carried out recently by [PERSON] et al. [56], who applied continuous PEF at two different stages of winemaking from Arinto and Moscatel white grape varieties. Firstly, PEF was used to treat grapes prior to pressing for must extraction (1.2 and 1.6 kV/cm) and later prior to bottling for stabilization/decontamination of produced wines (10 kV/cm). Both extraction and stabilization PEF treatments did not induce significant changes in the sensory characteristics (color, odor, and taste) of both wines. However, CIE color parameters analysis showed a significant increase in b* value (more intense yellow color) of PEF extracted Arinto and Moscatel wines. Regarding physicochemical characteristics, PEF extraction increased pH value and turbidity in both wines, while there was no impact on total acidity. Total phenols also increased with PEF extraction, but only in Arinto wine. In addition, PEF stabilization treatment had no effect on both wine varieties' quality characteristics, besides for a decrease in total phenols in the Moscatel wine. More recently, [PERSON] et al. [60] employed PEF (1.1 kV/cm, 10 us, 20 min) as an alternative wine aging method in four Xinomavro red wines in combination with various wood chips. They concluded that PEF had a minor to no effect on the enrichment of polyphenols, while the addition of wood chips showed a significant effect.