Juan Pedro Pérez Trujillo

A new method for the determination of carbonyl compounds in wines by headspace solid-phase microextraction coupled to gas chromatography-ion trap mass spectrometry.

A new analytical method for the determination of 18 carbonyl compounds [2,3-pentadione, hexanal, (E)-2-hexen-1-al, octanal, acetoin, (E)-2-octenal, furfural, decanal, (E)-2-nonenal, benzaldehyde, 5-methylfurfural, (E,E)-2-cis-6-nonadienal, β-damascenone, phenylacetaldehyde, acetophenone, (E,E)-2,4-decadienal, benzophenone, and vanillin] in wines using automated headspace solid-phase microextraction (HS/SPME) coupled to gas chromatography-ion trap mass spectrometry (GC-ITMS) was developed. Five fibers with different polarities were tested, and a study of the influence of various factors such as time and extraction temperature, desorption time and temperature, pH, and ionic strength and content in tannins, anthocyans, sucrose, SO(2), and alcoholic degree was conducted. These factors were optimized using a synthetic wine doped with the different analytes. The proposed method affords wide ranges of linearity, good linearity (r(2) > 0.998), values of repeatability and reproducibility lower than 5.5% of RSD, and detection limits ranging from 0.62 μg/L for β-damascenone to 129.2 μg/L for acetoin. Therefore, the optimized method was applied to the quantitative analysis of the aforementioned analytes in real samples of wines.

Volatile compounds of bottled wines with Denomination of Origin from the Canary Islands (Spain)

The concentrations of the following major volatile compounds: ethanal, ethyl acetate, methanol, 1-propanol, 1-butanol, 2-butanol, isobutanol and amylic alcohols were determined by gas chromatography in 153 bottled wines with Denomination of Origin (DO) from the Canary Islands. The volatile compounds analysed were within the normal intervals described for each type of wine. The content of methanol was low and does not represent a toxicological risk for consumers. Isobutanol, methanol and total higher alcohols permitted a better differentiation of wines according to the type. The island of production had more influence on the volatile profile than the DO within an island. Principal component analysis tend to separate red wines from the remainder of the wines and a differentiation of the red wines as a function of the vintage was observed.

A new method for the determination of short-chain fatty acids from the aliphatic series in wines by headspace solid-phase microextraction-gas chromatography-ion trap mass spectrometry.

A new analytical method for the determination of nine short-chain fatty acids (acetic, propionic, isobutyric, butyric, isovaleric, 2-methylbutyric, hexanoic, octanoic and decanoic acids) in wines using the automated HS/SPME-GC-ITMS technique was developed and optimised. Five different SPME fibers were tested and the influence of different factors such as temperature and time of extraction, temperature and time of desorption, pH, strength ionic, tannins, anthocyans, SO(2), sugar and ethanol content were studied and optimised using model solutions. Some analytes showed matrix effect so a study of recoveries was performed. The proposed HS/SPME-GC-ITMS method, that covers the concentration range of the different analytes in wines, showed wide linear ranges, values of repeatability and reproducibility lower than 4.0% of RSD and detection limits between 3 and 257 μgL(-1), lower than the olfactory thresholds. The optimised method is a suitable technique for the quantitative analysis of short-chain fatty acids from the aliphatic series in real samples of white, rose and red wines.

Conventional enological parameters of bottled wines from the Canary Islands (Spain)

The following conventional enological parameters: pH, total acidity, malic and tartaric acids, volatile acidity, density, reducing sugars, sucrose, alcoholic degree, ash, ash alkalinity, free sulfur dioxide, total sulfur dioxide, total polyphenols index, anthocyans and tannins were determined in bottled wines from the Canary Islands in order to characterize them. Mostly the parameters analysed fell within the legislated intervals and within the normal intervals described in the literature. Important differences are observed among the mean values of analyzed parameters in white, rose and red wines. Polyphenolic parameters, alcoholic degree and reducing sugars were the parameters that best differentiated the wines according to the vintage.

Amino Acids and Biogenic Amines Evolution during the Estufagem of Fortified Wines

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.