# Non-Thermal and Thermal Physical Procedures--Optimistic Solutions in the Winemaking Industry
## 2 The Use of Non-Thermal Techniques in Winemaking Optimization
### Pulse Electric Fields Treatment  
Several authors have examined the pulse electric field technique to extract phenolic components from red wines (Figure 5). For example, [PERSON] et al. [44] focused on the use of this treatment to increase must yield from Arinto (1.2 kV/cm) and Mocatel de Setubal (1.6 kV/cm) grapes. In this sense, a flow rate of 4 tons/h was subjected to a monopolar of 100 Hz and with a 50 \(\upmu\)s width. The color coordinates a* (green-red) and b* (blue-yellow) indicated important changes without also affecting the brightness L* of the wines obtained from the Arinto variety. The Mocatel samples showed significant variations in the chromatic parameters. Also, extraction using pulse electric fields did not affect the aroma characteristics of the wines, but some physicochemical parameters were changed, such as increasing the total phenolic content and the turbidity value. The results were influenced by the variety analyzed, thus requiring additional studies to apply pulse electric fields to other varieties as well.  
[PERSON] et al. [45] examined the effect of pulse electric field utilization and different assortments of wood fragments in order to optimize the aging process of some red wines obtained from the Xinomavro variety. The results indicated that the use of wood fragments caused a significant increase in the concentration of polyphenols in the wines. The application of the pulse electric field treatment led to a considerable increase in the concentration of the main volatile compounds in the wine, without having the same impact on the phenolic compounds. The data were significantly influenced by the type of oak fragments but also by the chemical composition of the wine. The investigated study provides arguments for considering that the procedure is a viable option for wine aging, considerably reducing work time.  
The results published by [PERSON] et al. [12] confirmed the sterilization effects of pulse electric fields in wine, having a lethal effect on different spoilage yeasts like _Saccharomyces_es, _Zygosaccharomyces_es, _Candida_, _Pichia_, and _Hansenula_ species. In the same study, the authors demonstrated that a high intensity (>15 kV/cm) of this type of treatment can favor the synthesis of various volatile components (thiols, esters, acids, etc.) in Merlot wines [9].  
[PERSON] et al. [46] suggested pulse electric fields as an efficient approach for improving phenolic extraction from grape skins during the maceration-fermentation process (when moderate (0.8 kV/cm) and high (5 kV/cm) intensities are used). After the application of a 13.2 kJ treatment, a major impact was registered on the sensory perception of Merlot wines produced by [PERSON] [47]. Pulse electric field-treated samples were found to have a sweeter taste and less sour aftertaste and were clearer. It was demonstrated that cold maceration combined with pulsed electric fields (moderate intensity) can improve the phenolic compound extraction in red wines [11].  
Applying a treatment with a total specific energy of 22 kJ/kg allowed [PERSON] et al. [48] to obtain an enhanced extraction of varietal aroma precursors from Garganega white grapes without significantly changing the color of the wine or the concentration in phenolic compounds, apparently increasing the wine's resistance to oxidation.  
[PERSON] et al. [49] studied the impact of a low intensity treatment (1 kV/cm for 30 min) for increasing the extraction of phenolic and volatile (phenylethyl alcohol, n-hexadecanoic acid, 14-heptadecenal, 16-heptadecenal etc.) compounds in grape-stem extracts.  
Analyzing the research that has been done, it can be shown that the indicated findings vary depending on the working conditions of the procedure, and there is no validated process in the regulations used for winemaking.