## 3 Identification and Quantification of Volatile and Semi-Volatile Compounds in Sparkling Wines
### Analytical Techniques  
Traditionally, the analysis of sparkling wines is commonly performed either by using gas chromatography (GC) or liquid chromatography (LC), often followed by mass spectrometry (MS) detection. These approaches offer robust capabilities for the separation and quantification of volatile and non-volatile compounds. In addition to these conventional methodologies, spectroscopic techniques such as ultraviolet-visible (UV-Vis), fluorescence, and nuclear magnetic resonance (NMR) have also been applied to investigate specific classes of compounds, including phenolics, proteins, and metabolites. Table 1 summarizes the most relevant analytical techniques reported in the literature, outlining their main applications in the context of sparkling wine analysis. \begin{table}
\begin{tabular}{c c c} \hline
**Technique** & **Detector Type** & **Analytical Purpose** & **Reference** \\ \hline \hline \multirow{7}{*}{\begin{tabular}{c} Gas \\ Chromatography \\ (GC) \\ \end{tabular} } & \
\begin{tabular}{c} Flame Ionization \\ Detector (FID) \\ \end{tabular} &
\begin{tabular}{c} Identification of volatile compounds through \\ retention times and quantification using external \\ calibration standards \\ \end{tabular} & [11; 19; 27; 78] \\  & & Volatile profile of sparkling wines in different \\  & & research areas: aroma characterization, varietal \\  & & differences (Cava, Champagne, Italian SW), \\  & & aging on lees, sulfur compounds, influence of \\  & & yeast strains and unification practices. \\ \end{tabular} } \\ \end{tabular}
\end{table} 
Table 1: Analytical techniques used in the identification and quantification of target compounds in sparkling wines. Figure 3: Conceptual decision diagram illustrating the selection of sample preparation techniques for the analysis of volatile and semi-volatile compounds in sparkling wines. The techniques are described in Sections 3.1.1–3.1.6. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Technique** & **Detector Type** & **Analytical Purpose** & **Reference** \\ \hline Gas & Mass Spectrometry & Effects of bottle closures, autolysis and aging, & [35,47,105] \\ Chromatography & Ofractometry (O) & Identification of key aroma compounds; & [45,73,106,107] \\ (GC) & Pulsed-Flame Photometric & Characterization of volatile sulfur compounds & [73,89] \\  & Detection (PFPD) & & \\ \hline Multidimensional & Time-of-flight detector & VOCs profiling in Italian and Moscatel & [65,108,109,110] \\ GC (GCxGC) & (TOF/MS) & sparkling wines. & [65,108,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,1  
explored alternative and innovative approaches. Sparkling wine is a complex matrix, characterized by a high concentration of dissolved CO\({}_{2}\), which necessitates prior degassing before analysis to prevent damage to analytical instrumentation. Yeast cells can be isolated by centrifugation, as described by [PERSON], [PERSON] et al. [13]. Alternative methods, such as electrophoresis and PCR (Polymerase Chain Reaction), have also been successfully employed [121]. [PERSON], [PERSON] et al. [21] used the MATS method (Microbial Adhesion to Solvents), which involves evaluating cell surface hydrophobicity to characterize microbial populations [21]. In addition to the classical chromatographic methods described above, other practices have been reported, including Size-Exclusion Low-Pressure Chromatography and Molecular Exclusion Chromatography. These techniques allow for the separation of macromolecules such as proteins and polysaccharides based on their size, offering valuable insights into the composition of sparkling wines at different production stages [29; 122]. The analysis of proteins in sparkling wine is critical, particularly in relation to foam stability and turbidity formation. Various methodologies have been reported:  
Bradford Assay, a colorimetric method for protein quantification [29; 48; 50; 52; 123; 124; 125].