## 3 Non-Thermal Technologies in Winemaking Process  
### High-Power Ultrasound (HPU) Effects on Varietal Aroma/Phenol Extraction and Wine Quality  
High-power ultrasound technology with intensities above 1 W/cm\({}^{2}\) and frequencies of 20-100 kHz refers to the use of ultrasonic waves at power levels that are able to cause significant changes in various foods or beverages to which they are applied [72]. Most commonly, HPU is applied through liquid medium, and for this purpose there is commercially available equipment in the form of ultrasonic baths where probes are mounted in housing below the device (indirect system) and directly in liquid-immersed ultrasonic probes (direct system) (Figure 3) [73]. The acoustic cavitation is the main mechanism responsible for sonochemical effects when applied to a liquid (Figure 4). It is characterized by formation, growth, and violent bubble disruption [74]. As the consequence of the bubble disruption, i.e., collapse extreme conditions are generated (temperature and pressure), resulting in the production of free radicals, shock waves, and shear forces [75]. Both bath and probe systems can effectively trigger this phenomenon, which can lead to cell rupture and the release of bioactive compounds from the plant tissue [76]. However, the nature of the sample determines whether the ultrasonic bath will be used (gentle treatment) or directly immersed probe system (more aggressive application). In winemaking, HPU can be applied at different stages from extraction, fermentation, and microbial stabilization to aging, with very promising results [7,8]. Table 2 summarizes recent applications and effects of HPU technology in this field. Recently, [PERSON] et al. [24] explored the effect of a HPU bath and probe on the quality composition of a young Cabernet Sauvignon red wine. Both HPU methods influenced phenolic, chromatic, and aroma composition of wine, whereby milder processing conditions resulted in a more beneficial effect. They found that ultrasound bath frequency had the greatest effect on red wine composition, followed by temperature and amplitude, while in HPU probe treatment, these were the following parameters: probe diameter, treatment time, and amplitude. In view of this, the authors pointed out that it is important to establish the most suitable HPU conditions to prevent excessive oxidation and reduction in phenolic and aroma compounds. In a same study, authors also explored the combined effect of HPU and antioxidants addition (SO\({}_{2}\) and glutathione) on wine composition during 6 months of aging, and found that HPU-treated wines showed lower concentration of phenolic compounds, but in combination with higher antioxidants addition this effect was delayed. Contrary, HPU did not induce major changes in large part of chromatic and aroma composition. Figure 3: High-power ultrasound bath (a) and probe (b) systems. © 2020 [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON]. Adapted from Application of High-Power Ultrasound in the Food Industry; originally published under CC BY 3.0 license. Available from: 10.5772/intechopen.90444 [[https://www.intechopen.com/chapters/70675](https://www.intechopen.com/chapters/70675)]([https://www.intechopen.com/chapters/70675](https://www.intechopen.com/chapters/70675)) (accessed on 14 March 2024) [73]. The same experimental methodology was applied on a young Grasevina white wine in another study by [PERSON] et al. [25]. The both applied HPU systems influenced wine chemical composition, without notable changes in color. Namely, higher bath temperatures resulted in a reduction in aroma compounds, while larger probe diameter along with higher amplitude had less effect on phenolic and aroma composition. HPU effects were also determined after 18 months of aging, with greater changes in HPU-treated wines with low antioxidant content. In global, both studies showed that HPU can be considered as an efficient and reliable technology for production of low-sulfite wines.