Browsing by Author "Ferreira, A. C. Silva"
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- 3-Hydroxy-4,5-dimethyl-2(5H)-furanone: a key odorant of the typical aroma of oxidative aged Port WinePublication . Ferreira, A. C. Silva; Jean-Christophe, Barbe; Bertrand, AlainApplication of aroma extract dilution analysis (AEDA) on organic extracts from Port wines barrel-aged over 40 years revealed 5 odor-active compounds corresponding to descriptors used to qualify the characteristic old wine aroma. One of the compounds, described as “nutty” and “spicy-like”, and present in at least 9 dilutions above the others, was perceived as particularly important. The compound responsible for this flavor was identified as 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon). The levels ranged from 5 to 958 μg/L for wines between 1 and 60 years old. It was also observed that during oxidative aging the concentration of this compound increased with time according to a linear trend (r > 0.95). Although the presence of 2-ketobutyric acid was verified, the constant rate of formation of sotolon with aging and its high correlation with sugar derivates (HMF, furfural) suggests other mechanisms, different from those reported for other wines. The flavor threshold of sotolon was evaluated in Port wine at 19 μg/L. Sensorial tests provided valuable information concerning sotolon impact on Port wine aroma. Samples supplemented with this substance were consistently ranked as older. In view of these results it can be expected that sotolon plays a pre-eminent role in the characteristic old Port wine aroma.
- Application of a robust analytical method for quantifying progestins in environmental samples from three Portuguese estuariesPublication . Amorim, V. E.; Morais, H.; Ferreira, A. C. Silva; Pardal, M. A.; Cruzeiro, C.; Cardoso, P. G.In the last years, progestins have raised special concerns for their documented negative effects on aquatic species, yet little is known about their environmental levels in surface waters and bioaccumulation in the trophic web. This study aimed to 1) adapt an extraction method for quantifying progestins in freeze-dried matrices, 2) validate the analytical procedure for three matrices: bivalve, polychaete, and crustacean, and 3) characterize levels of the four most prescribed synthetic progestins in key species across three Portuguese estuaries. Through the validated method, progestins were only quantifiable for the crustacean. Values were generally low, peaking with drospirenone values in Ria de Aveiro (1.33 ± 0.26 ng/g ww) and Tagus estuary (1.42 ± 0.55 ng/g ww), while Ria Formosa exhibited the lowest progestin concentrations (< 1 ng/g ww). This study enabled the development of a precise extraction and analytical method for quantifying steroid hormones in three distinct biological matrices.
- Aroma precursors of grapes: contribution of variety and vineyard traning system to port wine aromaPublication . Sousa, L.; Moreira, N.; Queiroz, J.; Oliveira, M.B.; Santos, C.; Oliveira, C.; Ferreira, A. C. Silva; Pinho, P. Guedes deIn order to evaluate the influence of the vine training system in the composition in terpenes, norisoprenoids and their precursors (carotenoids and glycosidic molecules), these compounds were quantified in grapes and Port wines belonging to two varieties: Touriga Nacional and Touriga Franca from Douro Region. The double cordon LYS 2/3 system was compared with the traditional method, the vertical shoot positioning VSP system. Touriga Nacional grapes and wines have higher contents in carotenoids, free and glycosylated fractions of terpenic and norisoprenoids compounds than Touriga Franca. In general, LYS 2/3 training system produced grapes and wines with high content in glycosylated fractions of terpenes and nor-isoprenoids, being more appropriate to the production of Port wines, which are submitted to an aging process.
- Aroma precursors of grapes: contribution of variety and vineyard traning system to port wine aromaPublication . Sousa, L.; Moreira, N.; Queiroz, J.; Oliveira, M. B.; Santos, C.; Oliveira, C.; Ferreira, A. C. Silva; Pinho, P. Guedes de
- Carotenoid compounds found in grapes and their relationship to plant water statusPublication . Oliveira, C.; Ferreira, A. C. Silva; Pinto, M. M. Mendes; Hogg, T.; Alves, F.; Pinho, P. Guedes de
- Carotenoid compounds in grapes and their relationship to plant water statusPublication . Oliveira, C.; Ferreira, A. C. Silva; Pinto, M. Mendes; Hogg, T.; Alves, F.; Pinho, Guedes deThe aim of this work was to study the relationship between carotenoid contents in grapevine berries and plant water status. For this purpose, a black grapevine variety, Vitis vinifera L. cv. Touriga Nacional, was studied. The experiments were carried out in the same Douro vineyards, with plants of the same age, in two different water retention soils. A higher water retention capacity soil, soil A, and a lower water retention capacity soil, soil B, were both in a 1.2 m deep silt-loam schist-derived soil. The training system was the double cordon trained and spur pruned. A first range was nonirrigated (NI) and a second one was irrigated (I), 60% of evapotranspiration (ET0). For soil B, a 30% of ET0 treatment was also applied. The plant water status was estimated by predawn leaf water potential. The effects of plant water status on berry growth were studied by measurement of the berry weight and total soluble solids (°Brix). The carotenoid profile was quantitatively determined by high-performance liquid chromatography/diode array. Carotenoids determined were â-carotene, lutein, neoxanthin, violaxanthin, and luteoxanthin. The comparison between irrigated and nonirrigated grapes was followed from 2 weeks before veraison until the ripe stage. Results showed that at harvest time, berries exposed to the NI had a lower weight than those exposed to the irrigated treatment (60% of ET0), 0.89 vs 1.36 g/berry and 0.94 vs 1.34 g/berry, for soils A and B, respectively. The irrigated treatment contributed to a higher sugar concentration in both soils. However, depending on the soil water retention capacity, the carotenoid contents were different in soils A and B. For soil A, the total carotenoid content was similar for both NI and I treatments. However, with regard to soil B, in irrigated treatment, levels of carotenoids were approximately 60% lower than those found for the NI. It seems to be possible to produce higher weight berries (with higher sugar levels) with similar carotenoid contents. On the other hand, soil characteristics had a larger influence than irrigation on the concentration of carotenoids in grapes, resulting in an important viticultural parameter to take into account in aroma precursor formation.
- Carotenoid profile in grapes related to aromatic compounds in wines from Douro regionPublication . Oliveira, Carla; Barbosa, Antonina; Ferreira, A. C. Silva; Guerra, Joaquim; Pinho, Paula Guedes deThe aim of this work was to characterize 8 representative grape varieties of the Douro Region using the carotenoid profile as it relates to aromatic compounds in the respective wines. Some other analyses, such as the determination of sugar, probable alcohol, pH, and total acidity, were also performed in an attempt to understand in which way the evaluated characteristics influenced by grape variety could contribute to the wine aroma. For the 3 y of the study, grape varieties with higher concentrations of carotenoids (Touriga Fêmea, Tinta Amarela, and Tinta Barroca) have lower values of free norisoprenoids, even with exceptions (Touriga Fêmea). Conversely, grape varieties with lower concentrations of carotenoids (Touriga Nacional, Sousão, and Tinto Cão) appear to have higher contents of free norisoprenoids, namely b-ionone for Touriga Nacional and vitispirane and 1,1,6-trimethyl-1,2- dihydronaphthalene (TDN) for Sousão and Tinto Cão. Touriga Nacional, followed by Touriga Fêmea, was the wine variety with the highest values of total free terpenols (linalol, a-terpineol, nerol, and geraniol), the presence of which is responsible for the floral aroma.
- Chemiomics: network reconstruction and kinetics of Port Wine agingPublication . Monforte, Ana Rita; Jacobson, Dan; Ferreira, A. C. SilvaNetwork reconstruction (NR) has proven to be useful in the detection and visualization of relationships among the compounds present in a Port wine aging data set. This view of the data provides a considerable amount of information with which to understand the kinetic contexts of the molecules represented by peaks in each chromatogram. The aim of this study was to use NR together with the determination of kinetic parameters to extract more information about the mechanisms involved in Port wine aging. The volatile compounds present in samples of Port wines spanning 128 years in age were measured with the use of GC-MS. After chromatogram alignment, a peak matrix was created, and all peak vectors were compared to one another to determine their Pearson correlations over time. A correlation network was created and filtered on the basis of the resulting correlation values. Some nodes in the network were further studied in experiments on Port wines stored under different conditions of oxygen and temperature in order to determine their kinetic parameters. The resulting network can be divided into three main branches. The first branch is related to compounds that do not directly correlate to age, the second branch contains compounds affected by temperature, and the third branch contains compounds associated with oxygen. Compounds clustered in the same branch of the network have similar expression patterns over time as well as the same kinetic order, thus are likely to be dependent on the same technological parameters. Network construction and visualization provides more information with which to understand the probable kinetic contexts of the molecules represented by peaks in each chromatogram. The approach described here is a powerful tool for the study of mechanisms and kinetics in complex systems and should aid in the understanding and monitoring of wine quality.
- Correlation between sensory data and chemical data: case study Touriga Nacional WinePublication . Ferreira, A. C. Silva
- Determination of carotenoid profiles in grapes, musts and fortified wines from Douro varieties of Vitis vinifera. Role of alcoholic fermentation on carotenoid levels in fortified winesPublication . Pinho, Paula Guedes de; Ferreira, A. C. Silva; Basto, A. I.; Hogg, T.