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- Acetic acid and ethyl acetate in Madeira wines: evolution with ageing and assessment of the odour rejection thresholdPublication . Miranda, Andreia; Pereira, Vanda; Pontes, Marisela; Albuquerque, Francisco; Marques, José C.Madeira wine is an internationally recognized fortified wine, characterized by a complex flavour and high longevity. Little is known about the impact of volatile acidity in its features along ageing. Thus, this work studied the evolution of acetic acid and ethyl acetate (volatile acidity main contributors) during the ageing processes used in Madeira wine production, canteiro and estufagem. Wines aged in canteiro for 6 up to 45 years were also evaluated. The odour rejection thresholds (ORT) were assessed in sweet (Malvasia) and dry (Sercial) wines with 5 and 10 years old, by a regular consumer panel and a non-regular consumer panel. The results showed that the formation trend of acetic acid and ethyl acetate is similar in both ageing processes and is favoured by the ageing, mostly in sweet wines. The ORT of ethyl acetate was in average 328 mg/L for both panels, while for acetic acid ranged between 1.96 and 5.72 g/L, depending on the evaluation panel and also on the age and sweetness degree of the Madeira wine. The ORT values expressed in volatile acidity ranged between 1.4 and 3.5 g/L, which are higher than the legal limits. The study pointed out that the olfactory perception of acetic acid and ethyl acetate in Madeira wines depends on their age and sweetness degree.
- Analytical methodologies for the determination of biogenic amines in wines: an overview of the recent trendsPublication . Miranda, Andreia; Leça, João M.; Pereira, Vanda; Marques, José CarlosBiogenic amines are naturally present in grapes or can occur during the vinification and aging processes, essentially due to the microorganism’s activity. When present in wines in high amount, biogenic amines may cause not only organoleptic defects but also adverse effects in sensitive human individuals, namely due to the toxicity of histamine, tyramine and putrescine. Even though there are no legal limits for the concentration of biogenic amines in wines, some European countries only recommend maximum limits for histamine. In this sense, biogenic amines in wines have been widely studied. The determination of amines in wines is commonly achieved by liquid chromatography, using derivatization reagents in order to promote its separation and detection. In alternative, other promising methodologies have been developed using capillary electrophoresis or biosensors, revealing lower costs and faster results, without needing a derivatization step. Nowadays, it is still a challenge to develop faster and inexpensive techniques or methodologies to apply in the wine industry. Thus, this review will be focused on the studies published in the last decade that involves the determination of biogenic amines in wines, highlighting the novelty, improvement and optimization of the analytical methods. The sample preparation procedures (such as derivatization reagents), the analytical methodologies and the new trends being followed by the wine industry are also described and discussed.
- 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.
- Amino acids and biogenic amines evolution during the estufagem of fortified winesPublication . Pereira, Vanda; Pereira, Ana C.; Pérez Trujillo, Juan P.; Cacho, Juan; Marques, José C.The current study was focused on the impact of accelerated ageing (heating step) on the amino acid and biogenic amine profiles of fortified wines. In this sense, three Madeira wines from two commonly used grape varieties (one red and the other white) were analysed during the heating, at standard (45∘ C, 3 months) and overheating (70∘ C, 1 month) conditions, following a precolumn derivatization procedure using iodoacetic acid, o-phthaldialdehyde, and 2-mercaptoethanol, carried out in the injection loop prior to RP-HPLC-FLD detection. Eighteen amino acids were identified, with arginine being the most abundant. An important decrease of the amino acid levels was detected during the standard heating (up to 30%), enhanced up to 61% by the temperature increase. Cysteine, histidine, and asparagine revealed the greatest decreases at 45∘ C. Conversely, some amino acids, such as asparagine, slightly increased. Four biogenic amines were identified but always in trace amounts. Finally, it was observed that the accelerated ageing did not favour the biogenic amine development. The results also indicate that the heating process promotes the amino acid transformation into new ageing products.
- Assessment of the development of browning, antioxidant activity and volatile organic compounds in thermally processed sugar model winesPublication . Pereira, Vanda; Santos, Magda; Cacho, Juan; Marques, José C.The study evaluates the contribution of the fructose and glucose's degradation for the Madeira wine's features. The browning index, antioxidant activity and volatile organic compounds developed by the glucose and fructose model systems simulating thermally processed sweet Madeira wines were assessed. Sixteen different fructose/glucose model systems were prepared in synthetic wine and stored at 50 C for 4 months. Then, three model wines were also submitted to 70 C for 1 month. The browning index and the antioxidant activity ranged between 0.00 and 0.27 AU and 3.0e65.3 mg(GAE)/L, respectively. The development of several volatile organic compounds was demonstrated (up to 47). The identified com pounds were mostly furans, with 5-hydroxymethylfurfural as the most abundant. For the first time, it was shown that the origin of sotolon in sweet wine can be associated with the acid-catalyzed fructose degradation mechanism. Other 2(5H)-furanones were also identified. It could be concluded that part of the browning, antioxidant activity and aroma compounds developed in sweet fortified wines is associ ated with the thermal degradation of fructose in acid medium.
- Odor detection threshold (ODT) and odor rejection threshold (ORT) determination of sotolon in Madeira wine: a preliminary studyPublication . Gaspar, João M.; Pereira, Vanda; Marques, José C.Madeira is a fortified wine, well renowned worldwide. It is during the aging process that its characteristic bouquet is developed, through the formation of specific aromas. Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is frequently pointed out as one of the molecules responsible for the aroma of the finest Madeiras. The present work serves as a preliminary insight on the sensorial impact of this compound in Madeira wine. The odor detection threshold of sotolon in a sweet-type Madeira was obtained by the 3-Alternative Forced Choice method. The estimated threshold value was obtained by 19 non-trained and non-expert panelists, within the spiked range 4–314 µg/L. An odor threshold of 112 µg/L was obtained using a 3-year-old Madeira with 6.3 ± 0.4 µg/L endogenous sotolon. This result is about 6-fold higher than those previously reported for other fortified wines. A Paired Preference test was chosen to determine the concentration at which the panelists would reject the wine spiked with sotolon. Nineteen panelists assessed a series of spiked concentrations ranging from 253–3464 µg/L. Within this range, it is not possible to define the concentration value from which the aroma of sotolon it is no longer pleasant. Thus, an odor rejection threshold could not be obtained. Indeed, the study also suggests that sotolon does not become unpleasant at higher concentrations.
- Evaluation of the feasibility of the electronic tongue as a rapid analytical tool for wine age prediction and quantification of the organic acids and phenolic compounds. The case-study of Madeira winePublication . Rudnitskaya, A.; Rocha, S. M.; Legin, A.; Pereira, V.; Marques, J. C.A set of fourteen Madeira wines comprising wines produced from four Vitis vinifera L. varieties (Bual, Mal vasia, Verdelho and Tinta Negra Mole) that were 3, 6, 10 and 17 years old was analysed using HPLC and an electronic tongue (ET) multisensor system. Concentrations of 24 organic acids, phenolic and furanic compounds were determined by HPLC. The ET consisting of 26 potentiometric chemical sensors with plasticized PVC and chalcogenide glass membranes was used. Significance of the effects of age and vari ety on the ET response and wine composition with respect to the organic acids, phenolics and furanic derivatives were evaluated using ANOVA—Simultaneous Component Analysis (ASCA). Significance of the effects was estimated using a permutation test (1000 permutations). It was found that effects of age, grape variety and their interaction were significant for the HPLC data set and only the effect of age was significant for the ET data. Calibration models of the HPLC and ET data with respect to the wine age and of the ET data with respect to the concentration of the organic acids and phenolics were calculated using PLS1 regression. Models were validated using cross-validation. It was possible to predict wine age from HPLC and ET data with the accuracy in cross-validation of 2.6 and 1.8 years respectively. The ET was capable of detecting the following components (mean relative error in cross-validation is shown in the parentheses): tartaric (8%), citric (5%), formic (12%), protocatehuic (5%), vanillic (18%) and sinapic (14%) acids, catechin (6%), vanillin (12%) and trans-resveratrol (5%). The ET capability of predicting Madeira wine age with good accuracy (1.8 years) as well as quantify of some organic acids and phenolic compounds was demonstrated.
- 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.
- Chemometric analysis of the volatile fraction evolution of Portuguese beer under shelf storage conditionsPublication . Rendall, Ricardo; Reis, Marco S.; Pereira, Ana Cristina; Pestana, Cristina; Pereira, Vanda; Marques, José CarlosIn this work we present a multivariate statistical analysis of the evolution of the volatile fraction of Portuguese beer over an extended period of 1 year under standard shelf storage conditions, using gas chromatography coupled with mass spectrometry (GC–MS). A systematic methodology is proposed for detecting the onset of meaningful changes in chemical composition during shelf storage and to monitor its evolution along time. We also put forward and discuss chemometric procedures for analyzing the contributions of different chemical com ponents in the definition of dynamic ageing trends. In summary, the chemometric analysis reveals that the chem ical composition of beer presents a statistically meaningful deviation from the reference scenario after a period of 7 months, although the deviation trend has its onset during the 6th month. The analysis performed also under lines the limitations of current variable contribution methods, and an alternative procedure was proposed based on the analysis in the original domain which finally led to a consistent and interpretable clustering structure of the volatile fraction compounds. Esters and higher alcohol compounds stand up on a cluster arrangement sug gesting that their strict control can effectively point out meaningful changes on beer aroma. Organic acids, name ly caprylic, capric and acetic acids can also be very helpful in that sense
- Modelling the ageing process: a novel strategy to analyze the wine evolution towards the expected featuresPublication . Pereira, Ana C.; Carvalho, Maria J.; Miranda, Andreia; Leça, João M.; Pereira, Vanda; Albuquerque, Francisco; Marques, José C.; Reis, Marco S.In this work we present a new strategy to monitor the wine evolution during the ageing process. More specifi cally, we validate a procedure for analyzing how wine evolves during the ageing process in relation to the desired and expected quality features and we apply the proposed methodology to the case of a Portuguese fortified wine, the Madeira wine, where we compare the wine evolution under two different ageing processes. The approach developed consists on modeling samples labeled as aged reference wines (5 year old Madeira wines), produced from four different grape varieties, and then analyze how and in which extent young wines (up to 3 years old) come closer to the reference data set. The analysis is based on a comprehensive set of chemical data, including: polyphenolic composition, organic acids, reducing sugars, color and oenological parameters, commonly used as routine quality control information. The study considers several feature extraction methods, such as: Principal Components of Analysis (PCA), Independent Component of Analysis (ICA) and Partial Least Squares (PLS). The classification methodologies tested were: Linear Discriminant Analysis (LDA), nearest neigh bor (k-NN) and Soft Independent Modelling by Class Analogy (SIMCA). The different options of preprocessing/ feature extraction/classification were evaluated and compared using a Monte Carlo approach. From our analysis, the best combination of feature extraction/classification methodologies was PLS/LDA, which presented a classification performance of approximately 90% for three out of the four classes modeled, and of about 78% for the remaining one. Regarding the wines monitored during the first 3 years, our analysis revealed that they indeed mature in relation to the five year old reference wines. Furthermore, for some wines, it is possible to detect differences between the two ageing processes analyzed. This study is of particular importance for this type of wines, where the ageing process plays a central role for attaining the expected quality levels, implying significant risks and costs for local and industrial producers. Notwithstanding the specific case study presented, the strategy outlined can be extrapolated to other products with similar characteristics in terms of their monitoring and process control