# Polypphenols: Natural Antioxidants to Be Used as a Quality Tool in Wine Authenticity
## 4 Current Analytical Approaches to Wine Authenticity
### Process Monitoring  
The last decade emerging disciplines have enabled thorough monitoring of the various processes involved in viticulture and enology. Below we present examples of process/treatment monitoring related studies involving polyphenolic compounds in viticulture and wine. Wine evolution studies may offer valuable information regarding process-related authentication including age evaluation or proper storage verification. Seasonal variability, rootstock as well vine training system are among the factors that affect polyphenol composition. [PERSON] et al. (2019) combined \({}^{1}\)H NMR and Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS)-based metabolomic approach coupled to advance chemometrics to evaluate the variability in Chenin Blanc and Syrah wines for two harvest seasons, two vine training systems and six rootstocks. They reported that wines produced from espalier training system were more abundant in caffeic acid derivatives while wines produced from a lyre system resulted in increased quantities in phenolic compounds, organic acids, and apocarotonoids [149]. There is an increasing demand for more sustainable management practices mainly organic and biodynamic farming protocols. \"Eco\"-friendly wines are frequently marketed at higher prices that are indirectly attributed to claimed health benefits. So far though, the results regarding the phenolic composition of wines from these \"alternative\" management protocols are contradictory. [PERSON] et al. (2013) concluded that no significant differences were observed among samples coming from conventional, organic, and biodynamic management protocols [150]. [PERSON] et al. (2016) reported that caffeic and coumaric acids, as well as other polyphenolic compounds, were in lower abundance in biodynamic grapes than in organic ones. Furthermore, it has been reported that concentration of total polyphenols and anthocyanins was found higher in organic wines in comparison to their biodynamic counterparts [151; 152]. However, in a more recent report from [PERSON] et al. (2019), it was stated that no statistically significant differences were observed regarding the concentrations of anthocyanins, flavonoids, phenolic, and cinnamic acids between organic and biodynamic wines [153]. Nonetheless, it must be stated that polyphenol composition cannot be easily compared between different agronomical treatments as it is severely influenced by genetic and environmental factors [23]. A number of studies target wine evolution. Various pigments and tannins have been identified among discriminant biomarkers for micro-oxygenated Sangiovese wines versus non-micro-oxygenatedones [154]. In another study, [PERSON] et al. (2019) studied wine chemistry involved in aging processes, employing a set of mono-varietal Queretaro Merlot samples as model system. With the use of Ultraviolet Visible (UV-VIS) absorbance-transmittance coupled with excitation emission matrix fluorescence, they discovered a rich (poly)-phenolics aromatic region, which was subsequently confirmed with NMR experiments [155]. Proper storage conditions are considered fundamental for preserving wine sensory attributes and this is considered a prerequisite for wine enthusiasts and especially wine retailers. In this context, [PERSON] et al. (2016) developed a holistic metabolic profiling method using hydrophilic interaction chromatography (HILIC) mass spectrometry to study the effect of typical domestic storage conditions as compared to optimum cellar conditions for five Sangiovese red wines and for a period of 24 months. They reported that quercetin, catechchin, malvidin 3-glucosidase, and pyranomalvidin 3-glucose were among the marker compounds affected by the different storage conditions. Queretin was found richer for domestic storage that was derived from the hydrolysis of quercetin 3-glucosidase in these conditions, while the latter three were more abundant in the case of optimum cellar storage [156].