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- PLS-R calibration models for wine spirit volatile phenols prediction by Near-Infrared SpectroscopyPublication . Anjos, O.; Caldeira, Ilda; Fernandes, Tiago A.; Pedro, Soraia; Vitória, Cláudia; Alves, Sheila Oliveira; Catarino, Sofia; Canas, SaraNear-infrared spectroscopic (NIR) technique was used, for the first time, to predict volatile phenols content, namely guaiacol, 4-methyl-guaiacol, eugenol, syringol, 4-methyl-syringol and 4- allyl-syringol, of aged wine spirits (AWS). This study aimed to develop calibration models for the volatile phenol’s quantification in AWS, by NIR, faster and without sample preparation. Partial least square regression (PLS-R) models were developed with NIR spectra in the near-IR region (12,500–4000 cm−1 ) and those obtained from GC-FID quantification after liquid-liquid extraction. In the PLS-R developed method, cross-validation with 50% of the samples along a validation test set with 50% of the remaining samples. The final calibration was performed with 100% of the data. PLS-R models with a good accuracy were obtained for guaiacol (r2 = 96.34; RPD = 5.23), 4-methyl-guaiacol (r2 = 96.1; RPD = 5.07), eugenol (r2 = 96.06; RPD = 5.04), syringol (r2 = 97.32; RPD = 6.11), 4-methylsyringol (r2 = 95.79; RPD = 4.88) and 4-allyl-syringol (r2 = 95.97; RPD = 4.98). These results reveal that NIR is a valuable technique for the quality control of wine spirits and to predict the volatile phenols content, which contributes to the sensory quality of the spirit beverages.
- PLS-R calibration models for wine spirit volatile phenols prediction by Near-Infrared SpectroscopyPublication . Anjos, O.; Caldeira, Ilda; Fernandes, Tiago A.; Pedro, Soraia; Vitória, Cláudia; Alves, Sheila Oliveira; Catarino, Sofia; Canas, SaraNear-infrared spectroscopic (NIR) technique was used, for the first time, to predict volatile phenols content, namely guaiacol, 4-methyl-guaiacol, eugenol, syringol, 4-methyl-syringol and 4-allyl-syringol, of aged wine spirits (AWS). This study aimed to develop calibration models for the volatile phenol’s quantification in AWS, by NIR, faster and without sample preparation. Partial least square regression (PLS-R) models were developed with NIR spectra in the near-IR region (12,500–4000 cm1) and those obtained from GC-FID quantification after liquid-liquid extraction. In the PLS-R developed method, cross-validation with 50% of the samples along a validation test set with 50% of the remaining samples. The final calibration was performed with 100% of the data. PLS-R models with a good accuracy were obtained for guaiacol (r2 = 96.34; RPD = 5.23), 4-methyl-guaiacol (r2 = 96.1; RPD = 5.07), eugenol (r2 = 96.06; RPD = 5.04), syringol (r2 = 97.32; RPD = 6.11), 4-methylsyringol (r2 = 95.79; RPD = 4.88) and 4-allyl-syringol (r2 = 95.97; RPD = 4.98). These results reveal that NIR is a valuable technique for the quality control of wine spirits and to predict the volatile phenols content, which contributes to the sensory quality of the spirit beverages.
- Influence of the storage in bottle on the antioxidant activities and related chemical characteristics of wine spirits aged with chestnut staves and micro-oxygenationPublication . Alves, Sheila Oliveira; Lourenço, Sílvia; Anjos, O.; Fernandes, Tiago A.; Caldeira, Ilda; Catarino, Sofia; Canas, SaraDifferent ageing technology of wine spirits (WSs) has been investigated, but little has been published on the chemical evolution of aged WS during storage in bottle. The purpose of this study was to examine how 12 months of storage in bottle affected the evolution of antioxidant activity (DPPH, FRAP and ABTS assays), total phenolic index (TPI) and low molecular weight (LMW) compounds content of the WSs aged through alternative technology using three micro-oxygenation levels (MOX) and nitrogen control (N). Results revealed the ability of phenolic compounds from aged WSs to scavenge free radicals during storage in bottle. Among the in vitro antioxidant-activity methods, FRAP assay was the more effective to differentiate WSs according to the ageing technology. Concerning the overall influence of storage in bottle on antioxidant activity, and TPI and LMW compounds content, the higher results were obtained for the MOX modalities (O15, O30 and O60), which showed a similar evolution. In summary, this study provides innovative information, demonstrating that the differences between the aged WSs imparted throughout the ageing process (resulting from different MOX levels) were mostly retained, and only slight modifications during storage in bottle were found.
- Characterisation of low molecular weight compounds of strawberry tree (Arbutus unedo L.) fruit spirit aged with oak woodPublication . Anjos, O.; Antunes, Carlos Alberto Lopes; Alves, Sheila Oliveira; Canas, Sara; Caldeira, IldaThere is a trend towards the commercialisation of strawberry tree fruit spirit (AUS) with wood ageing, motivated by its favourable sensory characteristics. Additionally, further studies are necessary to elucidate the optimal conditions regarding ageing time and toasting level. This study evaluated the changes in colour and low molecular weight compounds (LMWC) of AUS aged for three and six months using oak wood (Quercus robur L.) with light, medium and medium plus toasting levels. For this purpose, phenolic acids (gallic, ellagic, ferulic and syringic acids), phenolic aldehydes (vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde) and furanic aldehydes (furfural, 5-hydroxymethylfurfural and 5-methylfurfural) were quantified using the HPLC method. Chromatic characteristics, colour sensory analysis and total polyphenol index were also analysed. Fourier transform near-infrared spectroscopy (FT-NIR) was used to discriminate between samples. The results emphasized the favourable effect of oak wood contact on enhancing the colour and enriching AUS with low molecular weight compounds (LMWC). AUS aged in medium toasted wood exhibits high levels of total phenolic index, 5-hydroxymethylfurfural, furfural, coniferaldehyde, sinapaldehyde, sum LMWC and chromatic characteristics b* and C. Concentrations of syringaldehyde, ellagic acid, vanillin and syringic acid and a lighter colour (a* chromaticity coordinates) are higher in AUS aged with slightly more toasted wood. Nearly all analysed parameters showed an increase with ageing time. The FT-NIR technique allowed for the differentiation of aged AUS, focusing more on ageing time than on toasting level.
- The effect of transition metals on coniferaldehyde oxidation in wine spirits model solutionsPublication . Alves, Sheila Oliveira; Lourenço, Sílvia; Fernandes, Tiago A.; Anjos, O.; Caldeira, Ilda; Catarino, Sofia; Canas, SaraWood is known to be a complex biological system composed mainly of cellulose, hemicelluloses and lignin. Cellulose is commonly degraded by the thermal treatment of wood during coopering giving rise to HMF and 5- methylfurfural, while hemicellulose can generate pentose by hydrolysis, and posteriorly, furfural and its derivatives. Lignin transformations during ageing process of distillates are among the most important factors that may influence the quality of aged wine spirit (WS).
- Application of near-infrared spectroscopy to characterize volatile phenols and sensory profile of aged wine spiritsPublication . Anjos, O.; Caldeira, Ilda; Fernandes, Tiago A.; Pedro, Soraia; Vitória, Cláudia; Alves, Sheila Oliveira; Catarino, Sofia; Canas, SaraVolatile phenols are low molecular weight aromatic alcohols, with particular importance in wine spirits aged with wood due to their strong influence on sensory profile.
- Changes of the physicochemical characteristics of aged wine spirits during the storage in bottlePublication . Lourenço, Sílvia; Soares, Amélia; Mota, Deolinda; Anjos, O.; Caldeira, Ilda; Alves, Sheila Oliveira; Canas, SaraThe wine spirit (WS) is a specific beverage obtained by the distillation of wine. Initially, the wine distillate is essentially made up of ethanol and water, and its physicochemical characteristics mainly result from the wine and distillation system used. During the ageing process, the distillate contacts with the wood and, with the mediation of oxygen, organic compounds are extracted from the wood and undergo several reactions over time, thus altering the sensory and physicochemical characteristics of this spirit beverage. Traditionally, ageing is carried out in barrels, which is an expensive and time-consuming technology.1 To overcome these drawbacks, alternative technologies for a sustainable ageing of WS using wood staves combined with micro-oxygenation (MOX) has been studied by our team.
- Antioxidant ativities of wine spirits aged by a sustainable technology using chestnut wood staves and micro-oxygenationPublication . Alves, Sheila Oliveira; Lourenço, Sílvia; Anjos, O.; Caldeira, Ilda; Fernandes, Tiago A.; Catarino, Sofia; Canas, SaraAntioxidant ativities of wine spirits aged by a sustainable technology using chestnut wood staves and micro-oxygenation.
- Influence of the storage in bottle on the antioxidant activities and related chemical characteristics of wine spirits aged with chestnut staves and micro-oxygenationPublication . Alves, Sheila Oliveira; Lourenço, Sílvia; Anjos, O.; Fernandes, Tiago A.; Caldeira, Ilda; Catarino, Sofia; Canas, SaraDifferent ageing technology of wine spirits (WSs) has been investigated, but little has been published on the chemical evolution of aged WS during storage in bottle. The purpose of this study was to examine how 12 months of storage in bottle affected the evolution of antioxidantactivity (DPPH, FRAP and ABTS assays), total phenolic index (TPI) and low molecular weight (LMW)compounds content of the WSs aged through alternative technology using three micro-oxygenationlevels (MOX) and nitrogen control (N). Results revealed the ability of phenolic compounds fromaged WSs to scavenge free radicals during storage in bottle. Among the in vitro antioxidant-activity methods, FRAP assay was the more effective to differentiate WSs according to the ageing technology.Concerning the overall influence of storage in bottle on antioxidant activity, and TPI and LMW compoundscontent, the higher results were obtained for the MOX modalities (O15, O30 and O60), whichshowed a similar evolution. In summary, this study provides innovative information, demonstratingthat the differences between the aged WSs imparted throughout the ageing process (resulting from different MOX levels) were mostly retained, and only slight modifications during storage in bottle were found.
- Natural blending as a novel technology for the production process of aged wine spirits : potential impact on their qualityPublication . Lourenço, Sílvia; Anjos, O.; Caldeira, Ilda; Alves, Sheila Oliveira; Santos, Nádia; Canas, SaraThe blending of wine spirits (WSs) produced in different ageing conditions is a key operation to impart specific features, enhance complexity, increase the final product’s quality and ensure brand consistency over the years, but requires time, labour and experienced blenders. This work aimed to develop a novel technology, natural blending, towards innovation and a more sustainable production process, adding value to the final product. WSs were aged in 250 L barrels and in 1000 L stainless steel tanks with wood staves and micro-oxygenation (MOX), using Limousin oak and chestnut wood simultaneously at a 50:50 ratio (natural blending) and separately; after 18 months of ageing, the last ones underwent the blending operation at the same ratio. All WSs were bottled and thereafter the following traits were analysed: alcoholic strength, acidity, dry extract, total phenolic index, low molecular weight compounds by HPLC method, chromatic characteristics and sensory profile. No significant differences in the physicochemical characteristics and sensory profile between the WSs resulting from the two blending technologies were found. Natural blending did not induce changes in the characteristics imparted by each ageing technology. These findings point to natural blending as a reliable alternative to the blending operation, especially in combination with ageing in tanks with staves and MOX.