## 3 Non-Thermal Technologies in Winemaking Process
### High Hydrostatic Pressure (HHP) Effects on Wine Phenolics, Color, and Aroma
bruxellensis_ in red wine, as its culturability was not established immediately after processing, while the same HHP conditions were only able to decrease the population of _S. cerevisiae_ yeasts in sweet white wine. However, during a 90-day storage, the results showed that the population of _B. bruxellensis_ fully recovered after initial inactivation by HHP, indicating its ability to transition to a viable but nonculturable state, whereas the _S. cerevisiae_ population was completely reduced. Moreover, HHP treatments (100 and 200 MPa, 1-25 min) slightly decreased the content of total anthocyanins in red wine, while minor variations in total phenols and total color difference were not related to applied treatments. [PERSON] et al. [29] used HHP of 600 MPa for 5 min to treat five different table wines and found that HHP had very small or even no impact on wine quality characteristics (total phenolic content, antioxidant activity, color density, and pH) directly after treatment. After 2 months of storage, no significant differences were observed between total phenols, antioxidant activity (except of lower value in HHP Pinot Gris), and pH of pressurized and unpressurized wines. Additionally, some HHP-treated wines (Pinot Noir, Rose, and Pinot Gris) showed higher color density compared to the untreated ones. More recently, [PERSON] et al. [35] applied HHP (200-600 MPa for 5 min) on red raspberry wine and observed that HHP greatly affected the aroma and phenolic composition, as well as sensory quality. Among the applied treatments, HHP at 400 MPa resulted in considerably higher content of alcohols, esters, and ellagic acid. However, HHP conditions up to 400 MPa had no effect on the alcohol content of wine, while higher pressures (500-600 MPa) reduced its content, as well as the content of ellagic acid. In summary, these studies have shown that HHP provides certain benefits to the winemaking process, such as accelerating wine aging, reducing wine spoilage microorganisms, limiting the need for SO2, and improving some quality characteristics and stability of wines. These reports have also highlighted the trends in a multidisciplinary approach to the HHP processing of wine, which aims to produce high-quality wines with low or no SO2 by using combined physical and chemical methods. Among the various high pressure technologies, high-pressure treatment with supercritical CO2 (100 bar, 10% CO2, 10 min) has recently been proposed as a novel and effective method to reduce the use of SO2 in white grape must while ensuring microbial safety, preserving the phenolic composition and maintaining the sensory characteristics of the must [81]. In addition, the effect of HHP has been recently reviewed in terms of the extraction of bioactive compounds such as anthocyanins from grape/grape juice and their stability [13; 14; 15], indicating that this is also an important area under investigation by scientists, especially in terms of shortening macceration. In addition, HHP was admitted in 2019 by OIV Resolution OENO 594A-2019 [77] for discontinuous HHP processing of grapes and musts (>150 MPa), with the purpose of controlling the microbial population of grapes, reducing SO2 doses and accelerating macceration in red winemaking.