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- Impact of indigenous non-saccharomyces yeasts isolated from Madeira Island vineyards on the formation of ethyl carbamate in the aging of fortified winesPublication . Leça, João Micael; Pereira, Vanda; Miranda, Andreia; Vilchez, José Luis; Malfeito-Ferreira, Manuel; Marques, José CarlosThe impact of selected non-Saccharomyces yeasts on the occurrence of ethyl carbamate (EC) was evaluated. Hanseniaspora uvarum, Starmerella bacillaris, Pichia terricola, Pichia fermentans and Pichia kluyveri isolated from Madeira Island vineyards were inoculated in Tinta Negra musts. Urea, citrulline (Cit) and arginine (Arg) were quantified when the density of musts attained the levels to obtain sweet (1052 ± 5 g/L) and dry (1022 ± 4 g/L) Madeira wines. The urea concentration varied between 1.3 and 5.3 mg/L, Cit from 10.6 to 15.1 mg/L and Arg between 687 and 959 mg/L. P. terricola and S. bacillaris generated lower levels of urea (<2.5 mg/L), Cit (<11.0 mg/L) and Arg (<845.6 mg/L). The five resulting fortified wines, individually fermented by the selected non-Saccharomyces yeast, were exposed to laboratory-accelerated aging at 70 °C for 1 month. From the studied yeasts, P. terricola and S. bacillaris revealed a lower potential to form EC (<100 µg/L); therefore, both yeasts can be a useful tool for its mitigation in wines.
- Unveiling the evolution of Madeira Wine key metabolites: a three-year follow-up studyPublication . Pereira, Vanda; Leça, João M.; Freitas, Ana I.; Pereira, Ana C.; Pontes, Marisela; Albuquerque, Francisco; Marques, José C.Madeira wine (MW) encompasses an unusual oxidative ageing process that makes it distinc tive. Several metabolites have been related to its quality and safety, such as 5-hydroxymethylfurfural (HMF), furfural, sotolon, and ethyl carbamate (EC). These compounds were quantified over a three year period to assess their formation rate according to the ageing procedure used: canteiro vs. estufagem. Estufagem, which includes thermal processing of young MWs, promoted greater HMF, furfural, and sotolon accumulation, especially in sweet wines, in which sotolon contributed significantly to aroma (odour active values up to 17.5). Tinta Negra revealed a higher predisposition to form EC while Malvasia and Sercial were less prone to its formation. The formation of furfural, HMF, and EC strongly correlated with the ageing time. Sotolon had a strong correlation with the ageing time in canteiro (r = 0.79) and a moderate correlation in estufagem (r = 0.65). In both ageing procedures, sotolon, furfural, and HMF formation trends strongly correlated with each other (r = 0.74–0.90). In turn, EC also correlated with all furans (r = 0.51–0.85). Yellow tones (b*) correlated with these metabolites only when wines undergo estufagem. This study provides valuable insights to improve MW quality and safety management procedures.
- New insights into ethyl carbamate occurrence in fortified winesPublication . Leça, João M.; Pereira, Vanda; Miranda, Andreia; Vilchez, José Luis; Marques, José C.The occurrence of ethyl carbamate (EC) in fortified wines was studied testing different model wines under accelerated ageing (45 °C for 4 months and 70 °C for 1 month), to investigate the possibility of arginine (Arg) being a direct precursor of EC in fortified wines, comparing it with known major precursors, urea and citrulline (Cit). Wine main sugars were appraised as possible catalysts, as previously pointed out. Model wines showed that: Arg can induce the EC formation under accelerated ageing, even without being metabolised by microorganisms; although much less reactive, Arg can play a significant role since high residual levels can occur in young fortified wines; glucose (Glc) and fructose (Fru) suppressed the EC formation from urea and Cit pathways, in about 11–26%. Moreover, Madeira wine samples were investigated in order to appraise the eventual contribution of the alcoholic fortification. The results revealed that this step can promote a decrease of the amount of these EC precursors up to 46%. Despite preliminary, additional information about the EC formation in fortified wines was obrained namely for designing new mitigation strategies, which can pass through the reduction of residual Arg.
- Influence of crop system fruit quality, carotenoids, fatty acids and phenolic compounds in cherry tomatoesPublication . Fernandes, Igor; Leça, João M.; Aguiar, Roberto; Fernandes, Tomásia; Marques, José C.; Cordeiro, NereidaTomato is one of the most consumed vegetables in the world, and its intake is known to be beneficial for human health. The nutritional quality of tomato is connected with numerous factors namely the cultivation system. To achieve the highest fruit quality and yield, the cherry tomato (Lycopersicon esculentum Mill. var. Moscatel RZ) was cultivated in three cultivation systems and its nutritional quality was evaluated. The highest fruit productivity, 2135–2240 g plant-1 dry weight (dw), was observed for the cherry tomatoes grown in the soilless systems. The cherry tomato from the hydroponic culture had the highest protein (13.41% dw), lipid (3.20% dw), sugar (354.94 mg g-1 dw) and taste index (1.24). It also comprised high amounts of monounsaturated and polyunsaturated fatty acids, like oleic (1.28 mg g-1 dw) and linoleic acids (5.42 mg g-1 dw). With respect to cherry tomato from the organic culture, higher contents of carotenoids—lycopene (47.1 mg kg-1 dw) and polyphenols (56.7 mg GAE 100 g-1 dw) were verified. Flavonoids were the main family of phenolic compounds found in the cherry tomato. The highest levels of chalconaringenin (51.95 mg 100 g-1 dw) and rutin (39.69 mg 100 g-1 dw) were observed in the cherry tomatoes cultivated through organic practices. This study shows that the agronomic system greatly influences the different characteristics associated with fruit quality. Hydroponic cultures presented higher quality, namely texture and taste, while the higher amounts of bioactive compounds were found in the organic culture.
- Ethyl carbamate in fortified wines: mitigation and controlPublication . Leça, João Micael da Silva; Marques, José Carlos Antunes; Vílchez Quero, José LuisO carbamato de etilo (CE) é um composto que ocorre naturalmente em bebidas alcoólicas. A sua toxicidade aguda é baixa, mas o consumo continuado levanta algumas preocupações, razão pela qual a indústria de bebidas alcoólicas se comprometeu a reduzir os níveis de CE tanto quanto possível. Este estudo pretende desenvolver e avaliar estratégias para mitigar a formação de CE em vinhos fortificados, com o vinho Madeira como caso de estudo. Primeiramente, uma extração líquido-líquido miniaturizada seguida por cromatografia líquida de fase reversa com deteção por espectrometria de massa em tandem foi desenvolvida com um bom limite de quantificação. Esta metodologia permitiu a determinação simples e eficiente de CE em vinhos fortificados. Foi utilizada para analisar um conjunto representativo de amostras de vinho Madeira, cujos resultados evidenciaram que os vinhos mais velhos tendem a apresentar concentrações mais elevadas de CE. A evolução do CE e dos seus principais precursores foi estudada numa amostragem de vinhos doces e secos de castas tintas e brancas, submetidos a estufagem e canteiro. Os vinhos doces Tinta Negra estufados apresentaram a maior propensão para formar CE e concluiu-se que outros compostos ou características físico-químicas não reportadas podem influenciar a ocorrência do CE. A arginina é apresentada como um novo precursor de CE, menos reativo que a ureia e a citrulina, mas relevante devido aos significativos níveis residuais em vinhos. Os principais açúcares no vinho, glucose e frutose, suprimem a formação de CE pelas vias dos precursores mais reativos, em até 26%. A fortificação alcoólica, utilizada para interromper a fermentação, não é um processo crítico para a ocorrência dos precursores de CE. O impacto da inoculação de leveduras indígenas não-Saccharomyces foi avaliado: Pichia terricola e Starmerella bacillaris revelaram o menor potencial para formar CE e podem ser ferramentas úteis para a sua mitigação em vinhos fortificados.