Phenolic and furanic compounds of Portuguese chestnut and French, American and Portuguese oak wood chips

Botanical species used on aging process must be wisely and judiciously chosen, and for this selection, a basic knowledge of the chemical composition of woods is warranted. Aiming to contribute to extend the knowledge of the chemical composition of several wood species useful for enological purposes, we have focused our studies on Portuguese chestnut and French, American and Portuguese oak chips. The profile of low molecular weight phenolic composition of these chips was achieved, using an optimized extraction method based on pressurized liquid extraction, followed by the quantification of phenolic acids, phenolic aldehydes and furanic derivatives by high-performance liquid chromatography (HPLC-DAD). The identification of those compounds was also confirmed by LC-DAD/ESI-MS. This study allowed the determination of the low molecular phenolic composition of Portuguese chestnut and French, American and Portuguese oak wood. According to our results, the influence of the botanical species seems to be more relevant than the geographic origin of the wood species

Monitoring selected monomeric polyphenol composition in pre- and post-fermentation products of Vitis vinifera L. cv. Airén and cv. Grenache noir

A mass balance approach was used quantify select polyphenols in pre- and post-fermentation products resulting from the fermentation of Vitis vinifera cv. Grenache noir and Airén. For Grenache noir, the overall mass recovery was 102.7%. The main products were wine (78.3%), pomace (8.5%), lees (4.2%), and rachises (3.4%). Pomace was a rich source of all identified polyphenols. Lees sorbed significant amounts of gallic acid, catechin, epicatechin, malvidin-3-O-glucoside, malvidin-3-acetylglucoside, quercetin-3-O-glucoside, and quercetin. An approximately 200% increase in the total amount of gallic acid occurred during fermentation. For the Airén grapes, the overall mass recovery was >90%. The pomace, rachises, juice solids after settling, and lees constituted ∼50% of the total mass of products obtained; pomace alone accounted for 40% of the total product mass. Over 90% of the total amount of gallic acid, catechin and epicatechin and ∼50% of the quercetin-3-O-glucoside were found in the pomace

Monitoring selected monomeric polyphenol composition in pre- and post-fermentation products of Vitis vinifera L. cv. Airén and cv. Grenache noir

A mass balance approach was used quantify select polyphenols in pre- and post-fermentation products resulting from the fermentation of Vitis vinifera cv. Grenache noir and Airén. For Grenache noir, the overall mass recovery was 102.7%. The main products were wine (78.3%), pomace (8.5%), lees (4.2%), and rachises (3.4%). Pomace was a rich source of all identified polyphenols. Lees sorbed significant amounts of gallic acid, catechin, epicatechin, malvidin-3-O-glucoside, malvidin-3-acetylglucoside, quercetin-3-O-glucoside, and quercetin. An approximately 200% increase in the total amount of gallic acid occurred during fermentation. For the Airén grapes, the overall mass recovery was >90%. The pomace, rachises, juice solids after settling, and lees constituted ~50% of the total mass of products obtained; pomace alone accounted for 40% of the total product mass. Over 90% of the total amount of gallic acid, catechin and epicatechin and ~50% of the quercetin-3-O-glucoside were found in the pomace

The use of near infrared reflectance spectroscopy to identify the origin of oak shavings used in wine aging

Near infrared (NIR) reflectance spectroscopy combined with chemometrics was used to classify toasted and untoasted oak wood shavings sourced from two countries (France and USA). Oak wood shaving samples (n = 96) were scanned in the NIR region (680–2,500 nm) using a monochromator instrument operating in reflectance mode. Principal component analysis, partial least squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) were used to classify the samples according to their country of origin and level of toasting. Full cross validation (leave-one-out) was used as the validation method when classification models were developed. Correct classification rates of 83, 87 and 100 % for samples sourced from USA, France and toasted treatment were obtained using PLS-DA. For LDA, correct classification rates of 80.4, 85 and 100 % were achieved for samples sourced from USA, France and toasted treatment, respectively. These results demonstrated the ability of NIR spectroscopy to discriminate between oak wood shavings sourced from two different countries and two levels of toasting.Sijing Li, Kerry L. Wilkinson, Daniel Cozzolin

In-depth search focused on furans, lactones, volatile phenols, and acetals as potential age markers of Madeira wines by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry combined with solid phase microextraction

The establishment of potential age markers of Madeira wine is of paramount significance as it may contribute to detect frauds and to ensure the authenticity of wine. Considering the chemical groups of furans, lactones, volatile phenols, and acetals, 103 volatile compounds were tentatively identified; among these, 71 have been reported for the first time in Madeira wines. The chemical groups that could be used as potential age markers were predominantly acetals, namely, diethoxymethane, 1,1-diethoxyethane, 1,1-diethoxy-2-methyl-propane, 1-(1-ethoxyethoxy)-pentane, trans-dioxane and 2-propyl-1,3-dioxolane, and from the other chemical groups, 5-methylfurfural and cis-oak-lactone, independently of the variety and the type of wine. GC × GC-ToFMS system offers a more useful approach to identify these compounds compared to previous studies using GC−qMS, due to the orthogonal systems, that reduce coelution, increase peak capacity and mass selectivity, contributing to the establishment of new potential Madeira wine age markers. Remarkable results were also obtained in terms of compound identification based on the organized structure of the peaks of structurally related compounds in the GC × GC peak apex plots. This information represents a valuable approach for future studies, as the ordered-structure principle can considerably help the establishment of the composition of samples. This new approach provides data that can be extended to determine age markers of other types of wines