Browsing by Author "Pereira, Vanda"
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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.
- 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.
- 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.
- 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.
- 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
- Evaluation of fucoxanthin contents in seaweed biomass by vortex-assisted solid-liquid microextraction using high-performance liquid chromatography with photodiode array detectionPublication . Nunes, N.; Leça, João M.; Pereira, Ana C.; Pereira, Vanda; Ferraz, S.; Barreto, Maria Carmo; Marques, José C.; Carvalho, M.A.A. Pinheiro deFucoxanthin is considered an important marine bioactive compound with biological properties with promising effects, namely on health. A simple and efficient analytical methodology is proposed for its quantification in seaweed biomass by using vortex-assisted solid-liquid microextraction (VASLME) followed by reversed phase high-performance liquid chromatography (RP-HPLC) photodiode array detection (PDA) analysis. This microextraction uses reduced quantities of sample (25 mg) and solvent (300 μL of ethanol) to efficiently extract this high-valued xanthophyll, in a vortex time of 15 min. These extraction parameters were optimized performing a Central Composite Design (CCD) analysis, running 32 individual experiments. In turn, the method validation was assessed. The linearity of the method was confirmed (R2 = 0.99998) in a concentration range from 12 to 3600 μg·g−1 dw. Also, good sensitivity and accuracy results were observed through the LOD (3.33 μg·g−1 ), LOQ (10.09 μg·g−1 ) and recovery (varied from 95 to 97%) assessments. Good precision was also verified, with intra-day variation within 2.0–3.3%, and inter-day within 1.0–3.8%. Matrix effect was also evaluated and an acceptable variation of 3.4% was found. The method applicability was confirmed by the analysis of 22 seaweed biomass samples and fucoxanthin content was found to vary from about 10 to 853 μg·g−1 dw. This method demonstrated a good performance and can be successfully implemented for a rapid, reliable and accurate screening of fucoxanthin in seaweed biomass.
- Evaluation of wine colour under accelerated and oak-cask ageing using CIELab and chemometric approachesPublication . Carvalho, Maria João; Pereira, Vanda; Pereira, Ana C.; Pinto, João L.; Marques, José C.The present study aims to analyse the evolution of colour and browning of fortified wines submitted to oak and accelerated ageing induced by temperature, both traditional ageing processes of Madeira wines. These wines were follow ed during the first 2 years of ageing and were simultaneously compared to aged reference samples, in order to disclose if accelerated ageing favours the wine evolution. The data anal ysis approaches followed two strategies: the first one was based on the monitoring of wine colour parameters based on CIELab methodology, while the second strategy adopted an untargeted approach, taking advantage of all wine information comprised on the UV-vis spectrum. CIELab results indicated that the greatest variation (up to 92 %) occurs during the vinification, since it was observed that wines produced from the same grape variety (Tinta Negra) acquired different char acteristics already on the vinification processes. All wines tend to approach the reference samples during ageing, with the lowest ΔE* value obtained for Malvasia submitted to canteiro at 2 years of ageing (3.29 units). Sweet Tinta Negra wines, previously submitted to estufagem, presented the most pronounced colour change associated with ageing. The multi variate principal component analysis (PCA) model was built with aged reference samples to evaluate how young wines acquire the reference wine’s characteristics and revealed that accelerated ageing increases colour evolution and favours the homogeneity of Malvasia wines.
- 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.
- Impact of Non-Saccharomyces Yeast Fermentation in Madeira Wine Chemical CompositionPublication . Miranda, Andreia; Pereira, Vanda; Jardim, Humberto; Malfeito-Ferreira, Manuel; Marques, José CarlosMadeira wine is produced via spontaneous alcoholic fermentation arrested by ethanol addition. The increasing demand of the wine market has led to the need to standardize the winemak ing process. This study focuses on identifying the microbiota of indigenous yeasts present during Madeira wine fermentation and then evaluates the impact of selected indigenous non-Saccharomyces as pure starter culture (Hanseniaspora uvarum, Starmerella bacillaris, Pichia terricola, Pichia fermentans, and Pichia kluyveri) in the chemical and phenolic characterization of Madeira wine production. Re sults showed that the polyphenol content of the wines was influenced by yeast species, with higher levels found in wines produced by Pichia spp. (ranging from 356.85 to 367.68 mg GAE/L in total polyphenols and 50.52 to 51.50 mg/L in total individual polyphenols through HPLC methods). Antioxidant potential was higher in wines produced with Hanseniaspora uvarum (133.60 mg Trolox/L) and Starmerella bacillaris (137.61 mg Trolox/L). Additionally, Starmerella bacillaris stands out due to its sugar consumption during fermentation (the totality of fructose and 43% of glucose) and 15.80 g/L of total organic acids compared to 9.23 g/L (on average) for the other yeasts. This knowledge can be advantageous to standardizing the winemaking process and increasing the bioactive compounds, resulting in the production of high-quality wines.
- Is sotolon relevant to the aroma of Madeira Wine blends?Publication . Gaspar, João M.; Freitas, Ana I.; Zhao, Qianzhu; Leça, João M.; Pereira, Vanda; Marques, José C.Madeira wine (MW) oxidative aging results in the formation of several key aromas. Little is still known about their odor relevance to the aroma of the most commercialized MWs. This report presents an in-depth study of the odor impact of sotolon in MW blends. First, its odor perception was estimated in MWs according to ASTM E679, testing different 3-year-old (3-yo) commercial blends. The odor relevance of sotolon in the aroma of 3-, 5-, and 10-yo commercial blends (89 MWs) was then appraised by calculating its Odor Activity Value (OAV), after determining its content by RP-HPLC-MS/MS. The sotolon odor perception in MW was as low as 23 µg/L, although it was found that little differences in the wine matrix influenced its perception. OAVs varied between 0.1 and 22, increasing with the blend age. Considering that 16% of the OAVs are higher than 10 (mostly ≥ 10-yo), sotolon was found to be a key contributor to the overall aroma MW blends.
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