Table 5.

Phenolic compounds concentration from Vitis Vinifera varieties according to different extraction methodologies. n.d: not detected.

Technique	Methodology	Phenolic Compounds (mg/L)	Reference
Liquid–liquid microextraction	Method 1: 1 mL wine was mixed with 1 mL of ethyl acetate and 500 μL of acetonitrile and extracted for 10 s. The extraction was performed twice.	Total phenolic compounds: Red wine (48.74–196.07). Rose wine (31.11). White wine (11.18–30.39).	[198]
Solid-Phase microextraction	Method 2: Wine samples were prepared by mixing 8 mL of wine and 7 mL of water. The grapes were crushed for analysis and 8 g were weighed and extracted with 2 mL of ethanol using sonication for 5 min (50% amplitude). The entire extract was centrifuged at 4000 rpm for 5 min. Finally, the supernatant was passed to 15 mL vials and filled with water. For the analysis, polyacrylate fiber was put into the 15 mL sample at 25 °C for 10 min under continuous stirring. Then, the fiber was placed in the headspace of 10 μL of the derivatization reagent (bis(trimethylsilyl)trifluoroacetamide) for 15 min at 50 °C. Derivatization was used with the aim of converting the polar non-volatile compounds into volatile derivatives that could be quantified. Lastly, desorption was performed at 280 °C for 5 min and polyphenols were quantified by GC-MS.	Red wine:trans-resveratrol (0.04), cis-resveratrol (0.03), piceatannol (0.01), catechin (0.12), and epicatechin (0.05). Rosé wine:trans-resveratrol (0.01), cis-resveratrol (n.d.), piceatannol (n.d), catechin (0.11), and epicatechin (n.d). White wine:trans-resveratrol (0.02), cis-resveratrol (n.d.), piceatannol (n.d.), catechin (0.11), and epicatechin (n.d.). Red grape:trans-resveratrol (0.04), cis-resveratrol (n.d.), piceatannol (0.02), catechin (0.05), and epicatechin (0.04). White grape:trans-resveratrol (0.01), cis-resveratrol (n.d.), piceatannol (n.d.), catechin (0.09), and epicatechin (n.d.).	[199]
Headspace sorptive extraction	Method 3: 1 mL of wine was mixed with 5 mL of a hydroalcoholic solution (13% ethanol and pH = 3.5), 40 μL of internal standard solution, and 1.5 g of NaCl. A preconditioned polydimethylsiloxane stir bar (Twister) was suspended in the headspace of the vial for 3.5 h at 36.5 °C. Next, it was thermally desorbed for 30 s. Splitless thermal desorption was programmed from 40 °C to 240 °C (for 5 min) at 60 °C/min. The injection was performed with a ramp of 12 °C/min from −100 °C to 240 °C and held for 5 min. The analysis was carried out by GC-MS.	Total phenolic compounds: Verdejo (176.50), Tempranillo (361.40), Graciano (1712.80), Albariño (201.50), Garnacha (295.10), and Godello (169.30).	[200]
Ultrasound-assisted extraction	Method 4: The membrane was filled with 60 mg of MgSO4 and 25 μL of wine and placed in a 4 mL glass vial before the extraction solvent was added (1 mL to ensure the membrane was submerged). The vial was immersed in an ultrasound bath for 25 min. Then, the extraction device was removed and a nitrogen stream was used to dry the extract. Next, 30 μL of the derivatization agent (N,O-bis(trimethylsilyl) trifluoroacetamide with 1% trimethyl chlorosilane) was added and the vial was vortexed for 30 s and heated for 30 min (at 35 °C) to allow the derivatization process. Finally, 170 μL of the extraction solvent was added to the vial to reconstitute the derivatized analytes and they were heated for 15 min at the same temperature. The solution was analysed by GC-MS system.	Red wine: protocatechuic acid (3.75), p-coumaric acid (8.73), gallic acid (3.18), ferulic acid (n.d.), caffeic acid (17.17), sinapic acid (0.96), pterostilbene (n.d.), resveratrol (3.22), and (+)-catechin (1696.63). Rosé wine: protocatechuic acid (2.37), p-coumaric acid (22.30), gallic acid (0.47), ferulic acid (n.d.), caffeic acid (8.54), sinapic acid (1.03), pterostilbene (n.d.), resveratrol (2.27), and (+)-catechin (38.00). White wine: protocatechuic acid (1.34), p-coumaric acid (1.32), gallic acid (0.28), ferulic acid (n.d.), caffeic acid (6.67), sinapic acid (n.d.), pterostilbene (n.d.), resveratrol (2.30), and (+)-catechin (47.92).	[201]
Microwave-assisted technique	Method 5: 2 mL of wine were mixed with 100 µL of hexamethyldisilazane used as a derivatizing agent and microwave-assisted extraction was used with 40% of microwave power with a nominal power of 1200 w and output of 700 w for 180 s. Lastly, the sample was centrifuged at 1200 rpm. Analysis by GC-MS.	Cabernet Sauvignon: gallic acid (60.59), caffeic acid (21.56), resveratrol (1.32), (−)-epicatechin (26.24), and (+)-catechin (33.14). Syrah: gallic acid (47.12), caffeic acid (11.54), resveratrol (2.12), (−)-epicatechin (33.67), and (+)-catechin (36.58). Carménère: gallic acid (24.82), caffeic acid (11.09), resveratrol (1.38), (−)-epicatechin (11.13), and (+)-catechin (14.53). Merlot: gallic acid (15.62), caffeic acid (16.52), resveratrol (5.17), (−)-epicatechin (16.85), and (+)-catechin (21.80). Tannat: gallic acid (19.28), caffeic acid (21.49), resveratrol (1.40), (−)-epicatechin (11.75), and (+)-catechin (16.76).	[202]