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

Abstract

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 Â GCToFMS 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 Â 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.KEYWORDS: Age markers, Madeira wine, HS-SPME, GC Â GC-ToFMS ' INTRODUCTION Madeira wine is a fortified Portuguese wine produced in Madeira Island over the last centuries and plays an important role in the economy of the Island. The peculiar characteristics of Madeira wines arise from the specific and singular winemaking process. The fermentation process is stopped by the addition of natural grape spirit in order to obtain an ethanol content of 18-22% (v/v). Some wines undergo aging in wood casks in cellars at temperatures up to 30°C, and humidity levels between 70 and 75%, while the majority of wines are submitted to a baking process, i.e., the wine is placed in large coated vats, and the temperature is slowly increased at about 5°C per day and maintained at 45-50°C during at least 3 months. After this treatment, the wine is allowed to undergo a maturation process in oak casks for a minimum of 3 years. Finally, some Madeira wines were submitted to an aging process, from a minimum of 3 to 20 years or even longer.1,2 The aging process in oak casks is fundamental for the Madeira wine's unique sensorial properties. During this period, several reactions and migration of molecules from the oak to wine can occur, 3,4 which depends on some parameters, such as grape variety, wine making procedure, and oak characteristics (geographical origin, species of oak, seasoning of the staves, toasting, and age of cask), 5-9 among others. The establishment of potential age markers is important to detect frauds and to ensure the authenticity of the wine. F...

Phenol and Aroma Composition of White Wines Produced by Prolonged Fermentative Maceration and Maturation in Wooden Barrels

“…Significantly higher concentration of furans in these wines (Table 4) is in agreement with previous fi ndings, where furans were found to increase during maturation (35), which is favoured by the presence of lees and oxygen (6). The exclusive occurrence of the so-called oak lactones, together with the increased amounts of other identifi ed lactones in the wines produced by prolonged maceration and maturation (Table 4), most probably originated from wood, as reported previously (42). Acetals are formed during fermentation, but their content increases most signi fi cantly during oxidative conditions of maturation (35,42).…”

“…Besides that, it was previously found that the formation of ethylphenols positively correlates with maceration duration and temperature (41,42). Among benzenoids, 2-ethoxybenzyl alcohol was found only in the wines produced by prolonged maceration and maturation (Table 4).…”

“…Volatile phenols, benzenoids, furans, lactones and acetals Higher level of ethylphenols and 4-propylphenol in the wines produced by prolonged maceration and maturation (Table 4) was probably a result of the activity of Brett anomyces and Dekkera yeast species which favour aerobic conditions during maturation in wood (41,42). Besides that, it was previously found that the formation of ethylphenols positively correlates with maceration duration and temperature (41,42).…”

Allergic asthma exhaled breath metabolome: A challenge for comprehensive two-dimensional gas chromatography

“…GC × GC has proven to be a powerful technique in the analysis of complex samples and to detect trace components [55,56]. Automated processing of HS-SPME/GC × GC-ToFMS data was used to tentatively identify all peaks in the GC × GC chromatogram contour plots with signal-to-noise threshold > 80.…”

Effectiveness of high-throughput miniaturized sorbent- and solid phase microextraction techniques combined with gas chromatography–mass spectrometry analysis for a rapid screening of volatile and semi-volatile composition of wines—A comparative study

“…Since its development, this technique has become very popular and gained growing acceptance and increasing use in routine laboratories applications mainly to the sampling and analysis of environmental [33], food [34][35][36], forensic [37] and pharmaceutical samples [38,39]. Typically followed by GC in combination with mass spectrometric detection (MS) [40][41][42] or its multidimensional alternative, comprehensive two-dimensional GC (GC × GC-ToFMS) [43][44][45], SPME technique has been successfully used for wine samples.…”