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The production of flavonoid glycosides by removing rhamnose from rutinosides can be accomplished through enzymatic catalysis. Naringinase is an enzyme complex, expressing both α-L-rhamnosidase and β-D-glucosidase activities, with application in glycosides hydrolysis. To produce monoglycosylated flavonoids with naringinase, the expression of β-D-glucosidase activity is not desirable leading to the need of expensive methods for α-L-rhamnosidase purification. Therefore, the main purpose of this study was the inactivation of β-D-glucosidase activity expressed by naringinase keeping α-L-rhamnosidase with a high retention activity. Response surface methodology (RSM) was used to evaluate the effects of temperature and pH on β-D-glucosidase inactivation. A selective inactivation of β-D-glucosidase activity of naringinase was achieved at 81.5∘C and pH 3.9, keeping a very high residual activity of α-L-rhamnosidase (78%). This was a crucial achievement towards an easy and cheap production method of very expensive flavonoids, like prunin and isoquercetin starting from naringin and rutin, respectively.

“Cork taint” is a major problem in wine industry and is caused by contamination of wines. This contamination is usually attributed to wine cork stoppers and 2,4,6-trichloroanisole (2,4,6-TCA) is one of the compounds mostly associated to this off-flavour. In this work, a consumer panel performed “forced choice” triangular tests in order to measure Odour Detection Thresholds (ODT) and Taste Detection Thresholds (TDT) of 2,4,6-TCA in water, hydro-alcoholic solutions (11.5% and 18% ethanol) and white and red wines. A paired preference test was also performed by the panel in order to measure Odour Rejection Threshold (ORT) in white and red wine spiked with 2,4,6-TCA. Results obtained show that the ODT and the TDT for 2,4,6-TCA in water were 0.2 and 0.3 ng/L, respectively. In hydro-alcoholic solutions with 11.5% and 18% ethanol the ODT were 4 and 10 ng/L respectively. In red wine the ODT and the TDT were 0.9 and 1.7 ng/L and in white wine were 1.5 and 1.0 ng/L respectively. ORT for white was 10.4 ng/L and for red wines 16.0 ng/L. These results suggest that although this group of consumers detected very low concentrations of 2,4,6-TCA in wines, they did not reject the wine at these low concentration values.

The "cork taint" is a major problem in wine industry and may caused by the several sources of contamination although wine cork stoppers are usually subject to suspition: 2,4,6-trichloroanisole (TCA) has been frequently associated to this off-flavour. In this work, a consumer panel performed "forced choice" triangular tests in order to measure Odour Detection Thresholds (ODT) and Taste Detection Thresholds (TDT) of TCA in water, hydro-alcoholic solutions (11.5% and 18% ethanol) and white and red wines. A paired preference test was also performed by the panel in order to measure Odour Rejection Threshold (ORT) in white and red wines spiked with TCA. Results obtained show that the ODT and the TDT for TCA were respectively: 0.2 and 0.3 ng/ L in water, 0.9 and 1.7 ng/L in red wine and 1.5 and 1.0 ng/L in white wine. ODT were 4 and 10 ng/L respectively for hydro-alcoholic solutions with 11.5% and 18% ethanol. ORT for white wines was 10.4 ng/L and for red wines 16.0 ng/L. These results suggest that although this group of non trained assessors detected very low concentrations of TCA in wines, they did not reject the wine at these low concentration values. O denominado "gosto a rolha" é um problema de grande importância para a indústria vitivinícola e constitui um defeito que aparece por contaminação dos vinhos. Esta contaminação é normalmente atribuída à rolha de cortiça e o 2,4,6-tricloroanisol (TCA) é o composto mais frequentemente associado a este "off-flavour". Neste trabalho, um painel de consumidores efectuou ensaios triangulares de resposta obrigatória, com vista à determinação dos Limiares de Detecção Olfactivos (LDO) e Limiares de Detecção Gustativos (LDG) do TCA em água, soluções hidroalcoólicas (11,5 e 18% etanol) e vinho de mesa branco e tinto. Um ensaio de comparação por pares foi utilizado pelo painel para avaliar o Limiar de rejeição Olfactivo (LRO) em vinhos brancos e vinhos tintos aos quais foi adicionado TCA. Os resultados obtidos mostram que o LDO e LDG em água correspondem respectivamente a 0,2 e 0,3 ng/L, em soluções hidroalcoólicas a 11,5 e 18% o LDO foi de 4 e 10ng/L respectivamente. Nos vinhos tintos o LDO e LDG foi de 0,9 e 1,7 ng/L e nos vinhos brancos foi respectivamente 1,5 e 1,0. O LRO obtido para o vinho branco foi de 10,4ng/L e para o vinho tinto 16,0 ng/L. Os resultados obtidos indicam que, embora este grupo de consumidores tenha detectado a presença de TCA em baixas concentrações nas diferentes amostras testadas, não rejeitaram as amostras de vinho que apresentavam estes teores. Le «goût de bouchon» est un problème important dans l’industrie vinicole et est provoqué par la contamination des vins. Cette contamination est habituellement attribuée aux bouchons de liège et le 2,4,6-trichloroanisole (TCA) est l’un des composés la plupart du temps associés à ce goût. Dans ce travail, un panel de consommateurs a effectué des essais triangulaires de choisi «forcé» afin de mesurer les seuils de détection d’odeur (SDO) et les seuils de détection de goût (SDG) de TCA en eau, solutions hydroalcooliques (éthanol de 11.5% et de 18%) et vins blancs et rouges. Un épreuve de préférence par paire a été également exécuté par le panneau afin de mesurer le seuil de rejet d’odeur (SRO) en vin blanc et rouge pointu avec TCA. Les résultats obtenues pour les SDO et les SDG pour TCA dans l’eau étaient 0.2 et 0.3 ng/L, respectivement. Dans les solutions hydroalcooliques avec de l’éthanol de 11.5% et de 18% les SDO étaient 4 et 10 ng/L respectivement. En vin rouge les SDO et les SDG étaient 0.9 et 1.7 ng/L et en vin blanc était 1.5 et 1.0 ng/L respectivement. SRO pour le blanc était 10.4 ng/L et pour les vins rouges 16.0 ng/L. Ces résultats suggèrent que bien que ce groupe de consommateurs ait détecté des concentrations très basses de TCA en vins, ils n’aient pas rejeté le vin à ces valeurs basses de concentration.

The recovery of high added-value products from waste plant material has been an important issue with economic relevance for the pharmaceutical and food industries. The recovery of antioxidants from wine industry by-products is of great importance in the nutraceutical field. The aim of this study was to identify the main flavonol glycosides, present in winemaking by-products from two white grape varieties: ‘Arinto’ and ‘Moscatel’ using liquid chromatography with diode array and electrochemical detection. Liquid chromatography with electrospray and atmospheric pressure chemical ionization, in negative and positive modes, were also used to characterize the structures of the compounds detected by means of MS²and MS ³. In the by-products analysed quercetin-3-glucoside and quercetin-3-glucuronide were identified as well as kaempferol-3-glucoside. By-products from ‘Arinto’ variety showed higher levels of quercetin glycosides and kaempferol-3-glucoside than the by-products of ‘Moscatel variety’. Uvas, vinho e subprodutos da vinificação contêm diversos compostos fenólicos pertencentes ao grupo dos flavonóides, em elevadas concentrações. Os glicósidos de flavonóis estão entre os compostos fenólicos presentes nas uvas. A sua actividade biológica é de grande interesse para as indústrias farmacêutica, cosmética e alimentar, não só pela actividade antioxidante, mas também pelas suas propriedades anti-inflamatórias e anti-cancerígenas. O objectivo deste estudo foi identificar glicósidos de flavonóis maioritários em subprodutos da vinificação em branco das variedades ‘Arinto’ e ‘Moscatel’. Foram utilizadas metodologias analíticas que incluiram a cromatografia líquida acoplada a detectores de díodos e electroquímico. Cromatografia líquida com espectrometria de massa foi ainda utilizada com duas fontes de ionização à pressão atmosférica: electrospray (ESI) e ionização química (APCI), nas polaridades positiva e negativa no sentido de comparar resultados. Foram também efectuados ensaios MS²e MS³ para caracterizar as estruturas químicas dos glicósidos de flavonóis detectados. Nas amostras analisadas foi identificada a quercetina-3-glucósido e a quercetina-3-glucuronido e também o quempferol-3-glucósido. Os subprodutos da variedade ‘Arinto’ mostraram, proporcionalmente, maior teor de glicósidos de quercetina que quempferol-3-glucósido, quando comparados com os resíduos da variedade ‘Moscatel’. Le rétablissement de produits de haute valeur obtenue de la matière végétale est une question importante avec la pertinence économique pour les industries pharmaceutique, cosmétique et alimentaire, à cause de son activité antioxydant mais aussi pour ces propriétés antiinflammatoire et anti-cancérigène. Le rétablissement des antioxydants des sous-produits d’industrie vinicole est de grande importance dans le domaine nutraceutique. Le but de cette étude était d’identifier les principaux glycosides de flavonol dans les sousproduits de la vinification de deux variétés blanches de raisin: ‘Arinto’ et ‘ Moscatel’. La chromatographie liquide avec la detection par diode et électrochimique on été employées en tandem. La chromatographie liquide était également employée pour caractériser les structures des composés détectés par MS²et MS³en utilisant electrospray et l’ionisation chimique de pression atmosphérique, en modes négative et positive. Dans les sous-produits analysés quercétine-3-glucoside, quercétine-3-glucuronide et kaempférol-3-glucoside ont été identifiés. Les sous-produits de la variété d’ ‘Arinto’ ont des proportions plus élevée des glycosides de quercétine et kaempférol-3-glucoside en comparaison avec les sous-produits de variété ‘Moscatel ‘.