Tannin profile of different Monastrell wines and its relation to projected market prices

Quantitative and qualitative composition of proanthocyanidins and other polyphenols in commercial red wines and their contribution to sensorially evaluated tannicity

The analysis of proanthocyanidins (PA) in red wine has typically been conducted using few key methods, such as phloroglucinolysis or precipitation assays. Here, the content of PAs and other common polyphenol groups in commercial red wines were analyzed with a group-specific liquid chromatography-tandem mass spectrometry method. Besides concentrations, the method provides qualitative information about the detected compound groups in the form of two-dimensional (2D) chromatographic fingerprints. The 2D fingerprints of PAs have not been utilized in analysis of red wine before. For instance, 2D chromatographic fingerprints revealed that the complex PA compositions were qualitatively notably similar between many wine types, even when there were considerable differences in concentrations. Finally, 201 commercial red wines had been categorized as either tannic or medium tannic based on their sensorial evaluations. The content of PAs and three different groups of oligomeric adducts of malvidin glycosides and PAs were measured from these wines. The compositional features of the PAs and PA-malvidin glycoside adducts were more important than concentrations in explaining the perceived tannicity.

Proanthocyanidins composition in new varieties descended from Monastrell

BACKGROUND

The wine sector is constantly evolving, in order to adapt to consumer tastes. The organoleptic characteristics in wines are the main factors to obtain quality wines. Proanthocyanidins (PAs) are responsible in an important way for positive aspects in quality wines, such as body and color stability in red wines, but they are also responsible for sensory characteristics that can be negative for their quality when found in excessive concentrations. One strategy to improve grapevines and wines is to obtain new varieties, so our research institute has been selecting some of them from direct crosses between Monastrell and other considered premium varieties such as Cabernet Sauvignon and Syrah.

RESULTS

A quantitative analysis in grapes, seeds and wines was carried out during three consecutive seasons (2018, 2019 and 2020) in order to characterize PAs composition and concentration in the following new varieties: MC80 (Monastrell × Cabernet Sauvignon), MC98, MC4, MC18 and MS10 (Monastrell × Syrah). Other aspect to study was the extraction capacity of the different new varieties of PAs during maceration process into must/wine.

CONCLUSION

In general, the results showed higher concentrations in PAs in most crosses for the three seasons studied compared to Monastrell variety. It was remarkable that a higher concentration of epigallocatechin was found in most of the wines elaborated with the crosses, being a positive aspect from an organoleptic point of view, since this compound provides softness to the wines. © 2023 Society of Chemical Industry.

Changes in Skin Flavanol Composition as a Response to Ozone-Induced Stress during Postharvest Dehydration of Red Wine Grapes with Different Phenolic Profiles

In this study, the combined effect of partial postharvest dehydration and long-term ozone treatment was evaluated at 10 and 20% weight loss as a strategy to induce compositional changes in grape skin flavanols. Two separate trials were carried out in thermohygrometric-controlled chambers at 20 °C and 70% relative humidity. The first trial was conducted under an ozone-enriched atmosphere at 30 μL/L, whereas the second trial was performed under an air atmosphere as a control. Two red wine grape varieties were studied, Barbera and Nebbiolo (Vitis vinifera L.), for their different phenolic composition. Berry skin flavanol composition was determined by high-performance liquid chromatography after phloroglucinolysis and size-exclusion chromatography. The results showed that dehydration and ozone effects were variety-dependent. In Barbera skins, being characterized by lower proanthocyanidin contents, the two effects were significant and their combination showed interesting advantages related to lower proanthocyanidin loss as well as higher prodelphinidin and lower galloylation percentages. In Nebbiolo, skin flavanol composition was barely affected.

Evaluation of secondary metabolites, antioxidant activity, and color parameters of Nepali wines

We evaluated the quality of wines produced in Nepal in terms of phenolic, flavonoid, anthocyanin and tannin content, antioxidant capacity, and color parameters using spectrophotometric methods. The total phenolic content, total flavonoid content, and total antioxidant activities in Nepali wines ranged from 85.5 to 960.0 (mean = 360.5 ± 268.7) mg/L GAE, 40.9-551.3 (mean = 188.9 ± 161.5) mg/L QE, and 66.6-905.0 (mean = 332.8 ± 296.5) mg/L AAE, respectively. These parameters were significantly higher in red wines compared to white wines. The phenolic and flavonoid content showed strong correlation with each other as well as with antioxidant activities. Additional parameters measured included various color parameters and carbohydrates. The wine color showed strong correlation with phenol, flavonoid, and antioxidant activity, whereas this correlation was not significant with anthocyanin content. Multivariate analysis was carried out to better describe and discriminate the wine samples. Finally, we compared Nepali wines with wines from other countries.