Percorrer por autor "Ferreira, A.C. Silva"
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- Alternatives for avoiding degradation in ecological winePublication . Balboa-Lagunero, T.; Aznar, M.; Ferreira, A.C. SilvaOrganic wines are prone to suffer from oxidative degradation due to the restrictions in the winemaking. This work studies the influence of different chemical routes, due to thermal and oxidative processes, in the wine aromatic profile. The resistance to these processes after the addition of compounds with a presumably antioxidant capacity was evaluated. Ascorbic acid, resveratrol, calcium disodium ethylenediaminetetraacetate (EDTA), sulphur dioxide (SO2) and the polyphenols: gallic acid, epicatechin and caffeic acid, were tested. The oxidative estate by cyclic voltammetry, aromatic composition and general profiles and sensorial analysis were performed; obtaining interesting differences depending on the applied treatment. All samples gave a characteristic voltammetry signal; showing a remarkable decrease in the current intensity on those samples that suffer a deeper degradation. Regarding the chemical analysis results, the application of the metal chelator EDTA, apart from the SO2 treatment, might be of interest to partly reduce the oxidative effect. Sensory differences were only found in samples treated with SO2 and those that had the addition of polyphenols, due to the appearance in these last samples of a strong vegetable aroma not perceptible in the other treatments.
- Impact of phenolic compounds in strecker aldehyde formation in wine model systems: target and untargeted analysisPublication . Monforte, A.R.; Martins, S.I.F.S.; Ferreira, A.C. SilvaThe Strecker degradation of phenylalanine has been studied in a phenolic compound/phenylalanine wine model system. Six phenolic compounds (3,4-dihydroxybenzoic acid, gallic acid, caffeic acid, ferulic acid, catechin, and epicatechin) were compared in the formation of phenylacetaldehyde when in the presence of glucose or methylglyoxal (MG). The addition of glucose reduced the formation of Strecker aldehyde, independently of the phenolic compound. The addition of MG, on the other hand, increased phenylacetaldehyde formation for hydroxybenzoic acids and decreased phenylacetaldehyde formation for flavan-3-ols, confirming their capacity to trap the dicarbonyl compound. As a target phenolic compound, catechin was chosen to perform kinetic studies to further understand the reaction intermediates involved in the mechanism of phenylacetaldehyde formation, in particular, catechin o-quinone and catechin–MG adduct. The addition of glucose and MG increased the consumption of catechin, while a reduction in the respective o-quinone was observed, suggesting that these substrates have an impact in other reactions involving catechin. In that regard, for the first time, it was demonstrated that the catechin–MG adduct was capable of oxidizing and forming a new o-quinone, contributing to wine instability promoted by oxidation reactions.
- Influência do Oxigénio na Modificação da Composição Aromática dos VinhosPublication . Ferreira, A.C. Silva
- Role of Strecker aldehydes on beer flavour stabilityPublication . Pinho, M. P. Guedes de; Ferreira, A.C. SilvaIn this work, attempts were made in order to measure the importance of “Strecker aldehydes” on flavour stability of beer correlating chemical and sensory data. It has been observed that methional and phenylacetaldehyde accumulates during storage and that these molecules were well correlated with “Aroma Quality”. A “fresh beer” was spiked with methional, phenylacetaldehyde and also with trans-2-nonenal, singly and in combination, the “Similarity Value” was then determined, between samples and an “aged beer”. The highest value was 72 % when the three compounds were added simultaneously and the combination of the two Strecker aldehydes increases by 54 % the degree of similarity.
- Wine aroma development: impact of oxygenPublication . Ferreira, A.C. Silva