Chemical interpretation of oxidative phenomena in wines: causes and effects

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HS-SPME/GC-MS methodologies for the analysis of volatile compounds in cork material

Publication . Moreira, Nathalie; Lopes, P.; Cabral, M.; Pinho, P. Guedes de

Two methods based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography– ion trap mass spectrometry (GC-IT/MS) were proposed for the analysis of volatile organic compounds (VOCs) in cork material used in the production of cork stoppers. The effect of various factors affecting the extraction efficiency was carried out by means of a 24 full factorial design. The first method allowed the extraction of 17 terpenes by using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber (50/30 μm). The optimal conditions were achieved when cork extract (5 mL) added with 2.3 g of NaCl was extracted during 35 min at 55 °C. The second method allowed the identification of 41 carbonyl compounds after in-solution (5 mL) derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA, 2.3 mg/mL), followed by an incubation period of 6 min at 52 °C and extraction during 36 min at the same temperature, using a PDMS/DVB (50/30 μm) fiber. Both methods are simple, solvent free and fast. These methods were applied to the analysis of different cork raw material showing significant differences in the amounts of volatile compounds analyzed. Alcanfor and α-terpineol were the terpenes compounds present at highest amounts, and within carbonyl compounds analyzed, some samples presented a high level of butanal, octanal, nonanal, and glyoxal.

2016Journal article

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Influence of packaging and aging on the red wine volatile composition and sensory attributes

Publication . Moreira, Nathalie; Lopes, P.; Ferreira, H.; Cabral, M.; Pinho, P. Guedes de

This work studied the volatile composition and sensory properties of red wines after packaging under different configurations: bag-in-box (BIB) and glass bottles sealed with natural cork stoppers. The experiments were carried out over a period of 12 months and analysis were performed at initial time (just before packaging) and after 3, 6 and 12 months of storage. Volatile compounds composition was determined by two different analytical techniques which combined headspace solid-phase micro- extraction (HS-SPME) with gas chromatography-ion trap/mass spectrometry (GC-IT/MS). Sensory analysis and other enological parameters, such as free and total SO2 and color intensity, were also monitored. Results showed that, after one year of storage, BIB wines were characterized by higher levels of several carbonyl compounds when compared to bottled wines. Moreover, bottled wines sealed with cork stoppers retained much more free and total SO2 than wines in BIB. In addition, the premature wine development under BIB was confirmed by sensory analyses.

2016Journal article

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Development and optimization of a HS-SPME-GC-MS methodology to quantify volatile carbonyl compounds in Port wines

Publication . Moreira, Nathalie; Araújo, Ana Margarida; Rogerson, Frank; Vasconcelos, Isabel; Freitas, Victor de; Pinho, Paula Guedes de

A method based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-triple quadrupole/mass spectrometry detection (GC-TQ/MS) with a prior derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was developed to quantify carbonyl compounds in different categories of Port wines. Optimal extraction conditions were obtained incubating 2 ml of wine with 2.3 g/l of PFBHA for 10 min and extracted during 20 min at 32 °C. The method was validated for 38 carbonyl compounds (alkanals, alkenals, Strecker aldehydes, dialdehydes, ketones and furan aldehydes) with regard to linearity, repeatability, inter and intra-day precision and accuracy, showing that the method is suitable for the determination of carbonyl compounds in wines. Tawny wines with ‘indication of age’ (10–40 years old) presented the highest levels of some carbonyl compounds, such as propanal, pentanal, hexanal, Strecker aldehydes, diacetyl, methyl glyoxal, 3-pentanone and 2-furfural, whereas Ruby wines were characterized by the highest amounts of some unidentified compounds.

2019Journal article

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