Browsing by Author "Cabral, M."
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- HS-SPME/GC-MS methodologies for the analysis of volatile compounds in cork materialPublication . Moreira, Nathalie; Lopes, P.; Cabral, M.; Pinho, P. Guedes deTwo 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.
- Influence of packaging and aging on the red wine volatile composition and sensory attributesPublication . Moreira, Nathalie; Lopes, P.; Ferreira, H.; Cabral, M.; Pinho, P. Guedes deThis 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.
- Sensory attributes and volatile composition of a dry white wine under different packing configurationsPublication . Moreira, N.; Lopes, P.; Ferreira, H.; Cabral, M.; Pinho, P. Guedes deThe aim of this work was to study the effect of different configurations of packaging on the volatile composition and sensory properties of a white wine. Certain oenological parameters were also evaluated. Bag-in-box (BIB) and glass bottles sealed with two different cork stoppers, natural and Neutrocork (technical), were used in the experiments. Analysis were carried out before packaging and after 3, 6 and 12 months of storage. Results showed that wines packaged in BIB presented higher levels of brown color than wines in bottles sealed with corks. In all packaging configurations, the content of free SO2 decreased with storage time; however, BIB wines showed a lower content of free SO2 than bottle wines during 12 months. Moreover, wines under BIB presented a significant lower amount of 2-phenylethanol, 2-phenylethyl acetate, isoamyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, linalool and b-damascenone than bottled wines.