# Non-Thermal and Thermal Physical Procedures--Optimistic Solutions in the Winemaking Industry
## 3 The Influence of Thermal Technologies in Wine Quality  
### Microwave Application  
Several authors examined the impact of microwave treatment on wine parameters. Table 3 illustrates some of the published results that correlate the operating conditions of the microwave apparatus with the physicochemical parameters of wine. This treatment generated higher values in total dry extract and higher volatile acidity in the Busuioca de Bohotin samples analyzed by [PERSON] et al. [23], compared to other non-thermal techniques. [PERSON] et al. [34] obtained similar levels in anthocyanins content in Merlot wines when microwave maceration was compared to thermomaceration in an experimental study, but in a shorter time (15 min vs. 30 min), thus promoting reduced energy consumption. Furthermore, membrane proteins undergo conformational changes, resulting in the formation of pores in the cell wall. All of these processes promote the migration of chemicals from grape to must. The increase of phenolic compound extraction was analyzed, in comparison with classical thermomaceration. Similar to these results, [PERSON] et al. [57] obtained higher levels of total polyphenols in Feteasca neagra and Babesca neagra variants treated with microwaves at the maceration stage, compared with those that underwent thermal or classical skin maceration. [PERSON] et al. [58] studied the impact of classical maceration procedures (120 h) and microwave maceration (a power of 750 W at 15 vs. 30 min) on the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Intensity (MPa)** & **Time (min)** & **Temperature (\({}^{\circ}\)C)** & **Samples** & **Main Results** & **References** \\ \hline \multirow{9}{*}{500} & \multirow{9}{*}{5} & & & - & color parameters: b\({}^{*}\) remains unchanged, & \\  & & & & & whereas L\({}^{*}\) and a\({}^{*}\) drop. & \\  & & & & - & antioxidant activity is unchanged. & \\  & & & & - & no action on protein stability. & \\  & & & & - & no effect on the main physicochemical & \\  & & & & red wines & & parameters: acidity, free and total SO2, & \\  & & & & & alcoholic strength, malic and lactic acids & \\  & & & & & content, total sugar, pH value & \\  & & & & - & no impact on polyphenol oxidase activity. & \\  & & & & & - & lactic and acetic acid bacteria, as well as \\  & & & & & yeasts, are totally deactivated. & \\ \hline \multirow{2}{*}{100–350} & \multirow{2}{*}{0–30} & \multirow{2}{*}{25} & low-alcohol red wines & - & lethal effect on yeasts and bacteria (lactic and & \\  & & & & & acetic acid bacteria). & \\  & & & & - & no significant influence on sensory profile. & \\ \hline \multirow{2}{*}{350} & \multirow{2}{*}{10} & \multirow{2}{*}{8} & & - & significant diminution of microorganisms. & \\  & & & & - & lower dose of SO2. & \\ \multirow{2}{*}{350} & \multirow{2}{*}{10} & \multirow{2}{*}{8} & red wine & - & no variation in the structural properties of & \\  & & & & the main tannins, antioxidant activity, & \\  & & & & & phenolic profile, or chromatic characteristics. & \\ \hline \multirow{2}{*}{600} & \multirow{2}{*}{5} & \multirow{2}{*}{-} & white and red wines & - & notable increase in phenolic content, which is & \\  & & & white and red & & associated with increased antioxidant & \\ \multirow{2}{*}{600} & \multirow{2}{*}{5} & \multirow{2}{*}{-} & wines & - & activity. & \\  & & & & - & no effect on the physicochemical parameters. & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: High-pressure operating conditions correlated to wine physicochemical structure. quality of Babeasca neagra wines. The treatment generated some important changes in physicochemical parameters (higher reducing sugar value, increased density, total acidity, pH and total dry extract, lower volatile acidity) compared to classical maceration methods. Regarding color parameters, a significant decrease in clarity was registered, as well as an increase of the \"a*\" in the red-green coordinate, which demonstrate the efficiency of this procedure to obtain a better extraction and migration of color chemical compounds.