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The current research attempts to provide an alternative tool for grape maturity measurement related to the wine composition since, the classical parameters (weight grape berries, sugar content, titratable acidity), commonly used in the winemaking industry, do not provide any sensorial information. In this context, the evolution of terpenic compounds (TC) during ripening of four V. vinifera L. grape varieties - Bual, Malvasia, Sercial (white grapes) and Tinta Negra (red grapes), was investigated, in addition to the establishment of terpenic pattern, using headspace solid phase microextraction (HS-SPME) combined with GC–MS. Using the optimal analytical conditions were identified 62 TC in the investigated V. vinifera L. grapes. The integration of chromatographic and chemometric data provides a powerful strategy to identify potential maturity markers. The maximum potential of mono- and sesquiterpenic compounds was reached at maturity, whereas the highest levels of norisoprenoids were observed at véraison . Partial Least Squares Regression (PLS-R) was employed to describe the relationship between classical parameters and TC. Based on PLS-R models, three monoterpenic (linalool, α-terpineol, carvomenthol), one sesquiterpenic (bicyclogermacrene) and two norisoprenoids compounds (vitispirane I, β-damascenone) could be used to define the optimum harvest date. The obtained results represent a very important tool to support, in an objective way, the winemakers decision for long-term strategic planning based on the sensory potentialities of grape varieties and consequently improving the excellence of Madeira wine. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve the knowledge of phenolic content and antioxidant potential during ripening of different grape varieties (Malvasia, Sercial and Tinta Negra) used to produce Madeira wine. Rapid spectrophotometric methods were selected to obtain this information, since these methods could be used as a routine analytical procedure, being easy, simple, rapid, and cost-effective. A significant correlation was observed between total phenolic content and antioxidant capacity for all grape varieties under study, which suggests that phenolics either alone or in combination are responsible for the grapes antioxidant capacity. Our findings showed significant differences (p < 0.05) for phenolic content and antioxidant capacity for all the studied grape varieties. Sercial grapes showed the highest values of phenolics and antioxidant capacity. Moreover, grape ripening stages revealed a significant impact on grapes phenolic content and antioxidant capacity. This information could be used by viticulturists and winemakers to improve and define Vitis vinifera L. grapes harvest management in order to maximize its bioactive potential. [ABSTRACT FROM AUTHOR]

The varietal volatile profiles of pulp and skin fractions from the main red and white Vitis vinifera L. grape varieties used in the production of Madeira wine (Portugal) were established by headspace solid phase microextraction (SPME) combined with gas chromatography–quadrupole mass spectrometry (GC–qMS) tandem with chemometric tools. A total of 60 varietal volatile compounds — 27 in pulp and 42 in skin of V. vinifera L. grapes studied, were identified, including 27 monoterpenic, 26 sesquiterpenic and 7 C13 norisoprenoid compounds. Principal Component Analysis (PCA) and Hierarchical Clusters Analysis (HCA) results demonstrated that, independently of grape fractions, a distribution by grape variety (white and red) as well as by Terroir effect, was attained using the varietal volatiles from skin grape fraction. Bual, Malvasia Cândida and Malvasia Branca (white varieties) exhibited different varietal volatile profiles, independently of grape fractions, skin or pulp. This difference could be explained by the highest sesquiterpenic level found in Bual grape variety, and monoterpenic level found in Malvasia Cândida and Malvasia Branca grape varieties. The obtained data suggests that climatic factors, such as altitude, temperature and humidity influenced the varietal profile from the target varieties, as the varietal profile of grapes cultivated at Estreito de Câmara de Lobos (32°39′50.59″N; 16°58′48.28″W) and Jardim da Serra (32°41′42.36″N; 16°59′37.32″W) showed qualitative and quantitative differences (expressed as GC peak area) when compared to varietal profile of grapes cultivated at Estreito da Calheta (32°44′0.09″N; 17°11′14.80″W), independently of the grape fractions (pulp or skin). Moreover, the cultivation of recommended grapes to produce Madeira wines — Malvasia Branca, Terrantez and Bastardo, should be promoted as their varietal volatile profile is quite similar to that found in noble varieties (Malvasia Cândida and Sercial, respectively). [ABSTRACT FROM AUTHOR]

Abstract: The volatiles (VOCs) and semi-volatile organic compounds (SVOCs) responsible for aroma are mainly present in skin of grape varieties. Thus, the present investigation is directed towards the optimisation of a solvent free methodology based on headspace-solid-phase microextraction (HS-SPME) combined with gas chromatography–quadrupole mass spectrometry (GC–qMS) in order to establish the global volatile composition in pulp and skin of Bual and Bastardo Vitis vinifera L. varieties. A deep study on the extraction-influencing parameters was performed, and the best results, expressed as GC peak area, number of identified compounds and reproducibility, were obtained using 4g of sample homogenised in 5mL of ultra-pure Milli-Q water in a 20mL glass vial with addition of 2g of sodium chloride (NaCl). A divinylbenzene/carboxen/polydimethylsiloxane fibre was selected for extraction at 60°C for 45min under continuous stirring at 800rpm. More than 100 VOCs and SVOCs, including 27 monoterpenoids, 27 sesquiterpenoids, 21 carbonyl compounds, 17 alcohols (from which 2 aromatics), 10 C13 norisoprenoids and 5 acids were identified. The results showed that, for both grape varieties, the levels and number of volatiles in skin were considerably higher than those observed in pulp. According to the data obtained by principal component analysis (PCA), the establishment of the global volatile signature of grape and the relationship between different part of grapes—pulp and skin, may be an useful tool to winemaker decision to define the vinification procedures that improves the organoleptic characteristics of the corresponding wines and consequently contributed to an economic valorization and consumer acceptance. [ABSTRACT FROM AUTHOR]