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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.
- A sensitive method for the rapid determination of underivatized ethyl carbamate in fortified wine by liquid chromatography-electrospray tandem mass spectrometryPublication . Leça, João M.; Pereira, Vanda; Pereira, Ana C.; Marques, José C.This work presents the optimization of a miniaturized liquid-liquid extraction (mLLE) followed by reversed-phase liquid chromatography-electrospray tandem mass spectrometry (RP-HPLC-MS/MS) for the determination of ethyl carbamate (EC) in fortified wine, without using derivatizing agents. The mLLE was optimized by an experimental design. Thus, 15 mL of wine and 8 mL of ethyl acetate were used for the extraction. After concentration, each extract was injected into the HPLC MS/MS equipment and the characteristic secondary ion transition of EC (m/z = 90.10 → 62.05) was used for the quan tification purposes. The proposed method presented a good lin earity (R2 = 0.9999) and a high sensitivity with low limits of detection (LOD) and quantification (LOQ), 0.17 and 0.52 μg L−1 , respectively. The precision (repeatability and reproducibility) never exceeded 8% of variation, and the recoveries varied between 93 and 114%. The applicability of the method was checked through the analysis of 24 fortified wines, with EC values ranging between 23 ± 1 and 194 ± 5 μg L−1 . All chromatograms revealed good peak resolutions. This new method is efficient for the simple, fast, and reliable determination of EC in fortified wines, providing great sensitivity without using derivatizing agents or large volumes of organic solvents.
- 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.
- 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.
- Quantification of polyphenols with potential antioxidant properties in wines using reverse phase HPLCPublication . Paixão, Neuza; Pereira, Vanda Nulita Gomes; Marques, José C.; Câmara, José S.A RP-HPLC method with photodiode array detection (DAD) was developed to separate, identify and quantify simultaneously the most representative phenolic compounds present in Madeira and Canary Islands wines. The optimized chromatographic method was carefully validated in terms of linearity, precision, accuracy and sensitivity. A high repeatability and a good stability of phenolics retention times (a3%) were obtained, as well as relative peak area. Also high recoveries were achieved, over 80.3%. Polyphenols calibration curves showed a good linearity (r2 A0.994) within test ranges. Detection limits ranged between 0.03 and 11.5 lg/mL for the different polyphenols. A good repeatability was obtained, with intra-day variations less than 7.9%. The described method was successfully applied to quantify several polyphenols in 26 samples of different kinds of wine (red, ros and white wines) from Madeira and Canary Islands. Gallic acid was by far the most predominant acid. It represents more than 65% of all phenolics, followed by p-coumaric and caffeic acids. The major flavonoid found in Madeira wines was trans-resveratrol. In some wines, (–)-epicatechin was also found in highest amount. Canary wines were shown to be rich in gallic, caffeic and p-coumaric acids and quercetin.
- HPLC-DAD methodology for the quantification of organic acids, furans and polyphenols by direct injection of wine samplesPublication . Pereira, Vanda Nulita Gomes; Câmara, José S.; Cacho, Juan; Marques, José C.This article proposes a simple and sensitive HPLC method with photo-diode array detection for the analysis of organic acids, monomeric polyphenols and furanic compounds in wine samples by direct injection. The chromatographic separation of 8 organic acids, 2 furans and 22 phenolic compounds was carried out with a buffered solution (pH 2.70) and acetonitrile as mobile phases and a difunctionally bonded C18 stationary phase, Atlantis dC18 (250 4.6 mm, 5mm) column. The elution was performed in 12 min for the organic acids and in 60 min for the phenolic compounds, including phenolic acids, stilbenes and flavonoids. Target compounds were detected at 210 nm (organic acids, flavan-3-ols and benzoic acids), 254 nm (ellagic acid), 280 nm (furans and cinnamic acid), 315 nm (hydroxycinnamic acids and trans-resveratrol) and 360 nm (flavonoids). The RSD for the repeatability test (n55) of peak area and retention times were below 3.1 and 0.3%, respectively, for phenolics and below 1.0 and 0.2% for organic acids. The RSDs expressing the reproducibility of the method were higher than for the repeatability results but all below 9.0%. Method accuracy was evaluated by the recovery results, with averaged values between 80 and 104% for polyphenols and 97–105% for organic acids. The calibration curves, obtained by triplicate injection of standard solutions, showed good linearity with regression coefficients higher than 0.9982 for polyphenols and 0.9997 for organic acids. The LOD was in the range of 0.07–0.49 mg/L for polyphenols (cinnamic and gallic acids, respectively) and 0.001–0.046 g/L for organic acids (oxalic and lactic acids, respectively). The method was successfully used to measure and assess the polyphenolic fingerprint and organic acids profile of red, white, rose ´ and fortified wines.
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