Oxygen-induced faults in bottled white wine: A review of technological and chemical characteristics

Aroma determination in alcoholic beverages: Green MS-based sample preparation approaches

Aroma determination in alcoholic beverages has become a hot research topic due to the ongoing effort to obtain quality products, especially in a globalized market. Consumer satisfaction is mainly achieved by balancing several aroma compounds, which are mixtures of numerous volatile molecules enclosed in challenging matrices. Thus, sample preparation strategies for quality control and product development are required. They involve several steps including copious amounts of hazardous solvents or time-consuming procedures. This is bucking the trend of the ever-increasing pressure to reduce the environmental impact of analytical chemistry processes. Hence, the evolution of sample preparation procedures has directed towards miniaturized techniques to decrease or avoid the use of hazardous solvents and integrating sampling, extraction, and enrichment of the targeted analytes in fewer steps. Mass spectrometry coupled to gas or liquid chromatography is particularly well suited to address the complexity of these matrices. This review surveys advancements of green miniaturized techniques coupled to mass spectrometry applied on all categories of odor-active molecules in the most consumed alcoholic beverages: beer, wine, and spirits. The targeted literature consider progresses over the past 20 years.

Mechanisms of the initial stage of non-enzymatic oxidation of wine: A mini review

Non-enzymatic oxidation is a primary factor affecting wine quality during bottling or aging. Although red and white wines exhibit distinct responses to oxidation over time, the fundamental mechanisms driving this transformation remain remarkably uniform. Non-enzymatic oxidation of wine commences with the intricate interplay between polyphenols and oxygen, orchestrating a delicate redox dance with iron and copper. Notably, copper emerges as an accelerant in this process. To safeguard wine integrity, sulfur dioxide (SO2) is routinely introduced to counteract the pernicious effects of oxidation by neutralizing hydrogen peroxide and quinone. In this comprehensive review, the initial stages of non-enzymatic wine oxidation are examined. The pivotal roles played by polyphenols, oxygen, iron, copper, and SO2 in this complex oxidative process are systematically explored. Additionally, the effect of quinone formation on wine characteristics and the intricate dynamics governing oxygen availability are elucidated. The potential synergistic or additive effects of iron and copper are probed, and the precise balance between SO2 and oxygen is scrutinized. This review summarizes the mechanisms involved in the initial stages of non-enzymatic oxidation of wine and anticipates the potential for further research.

Development of a Fully Automated Method HS-SPME-GC-MS/MS for the Determination of Odor-Active Carbonyls in Wines: a "Green" Approach to Improve Robustness and Productivity in the Oenological Analytical Chemistry

The aim of this study was the optimization and validation of a green, robust, and comprehensive method for the determination of volatile carbonyl compounds (VCCs) in wines that could be added as a new quality control tool for the evaluation of a complete fermentation, correct winemaking style, and proper bottling and storage. A HS-SPME-GC-MS/MS method was optimized and automated using the autosampler to improve overall performance. A solvent-less technique and a strong minimization of all volumes were implemented to comply with the green analytical chemistry principles. There were as many as 44 VCC (mainly linear aldehydes, Strecker aldehydes, unsaturated aldehydes, ketones, and many other) analytes under investigation. All compounds showed a good linearity, and the LOQs were abundantly under the relevant perception thresholds. Intraday, 5-day interday repeatability, and recovery performances in a spiked real sample were evaluated showing satisfactory results. The method was applied to determine the evolution of VCCs in white and red wines after accelerated aging for 5 weeks at 50 °C. Furans and linear and Strecker aldehydes were the compounds that showed the most important variation; many VCCs increased in both classes of samples, whereas some showed different behaviors between white and red cultivars. The obtained results are in strong accordance with the latest models on carbonyl evolution related to wine aging.

Non-enzymatic browning of wine induced by monomeric flavan-3-ols: A review

Non-enzymatic browning occurs widely in both white and red wines, and it has a huge impact on the color evolution and aging potential. Previous studies have proved that phenolic compounds, especially those with catechol groups, are the most important substrates involved in browning reactions of wine. This review focus on the current knowledge of non-enzymatic browning in wine resulting from monomeric flavan-3-ols. First, some relevant aspects of monomeric flavan-3-ols are introduced, including their structures, origins, chemical reactivities, as well as potential impacts on the organoleptic properties of wine. Second, the mechanism for non-enzymatic browning induced by monomeric flavan-3-ols is discussed, with an emphasis on the formation of yellow xanthylium derivatives, followed by their spectral properties and effects on the color change of wine. Finally, attentions are also be given to the factors that influence non-enzymatic browning, such as metal ions, light exposure, additives in winemaking, etc.

Microclimate of Grape Bunch and Sunburn of White Grape Berries: Effect on Wine Quality

This research aimed to evaluate the composition of wines made with white grapes which are particularly susceptible to sunburn symptoms due to the absence of anthocyanin. Sunburn is a complex physiological dysfunction leading to browning or necrosis of berry tissues. In vintage 2021, the canopy of 'Verdeca' grapevines grown in Salento, South Italy, was differently managed by sun exposing or shading the bunches. Micrometeorological conditions were studied at different levels. Grapes were vinified, comparing the winemaking with and without skin maceration. The vegetative-productive balance of plants was not substantially modified. On the contrary, a significant effect was observed on the quality and quantity of grapes produced: smaller berries with sunburn symptoms were found on unshaded bunches. This influenced the percentage distribution among skin, pulp and seeds, causing a decrease in must yield of up to 30%. The pH was significantly higher in macerated wines made using shaded grapes, due to a lower titratable acidity and to significant impacts on the acid profile. Obviously, maceration produced a higher extraction of phenolics in wines, which reached their maximum in wines made with sunburned grapes. The absorbance at 420 nm, index of yellow color, was also significantly higher in sunburned grapes, indicating greater oxidation. Even though excessive grape sun-exposure could negatively affect the perception of white wines made without maceration (resulting in more oxidative character), the sensory quality of orange/amber wines was not significantly impacted by the presence of sunburned grapes. Thus, this winemaking technique could be particularly interesting to set up a production strategy adapted to viticultural regions strongly affected by climate change.

Derivatization Strategies in Flavor Analysis: An Overview over the Wine and Beer Scenario

Wine and beer are the most appreciated and consumed beverages in the world. This success is mainly due to their characteristic taste, smell, and aroma, which can delight consumer’s palates. These olfactory characteristics are produced from specific classes of volatile compounds called “volatile odor-active compounds” linked to different factors such as age and production. Given the vast market of drinking beverages, the characterization of these odor compounds is increasingly important. However, the chemical complexity of these beverages has led the scientific community to develop several analytical techniques for extracting and quantifying these molecules. Even though the recent “green-oriented” trend is directed towards direct preparation-free procedures, for some class of analytes a conventional step like derivatization is unavoidable. This review is a snapshot of the most used derivatization strategies developed in the last 15 years for VOAs’ determination in wine and beer, the most consumed fermented beverages worldwide and among the most complex ones. A comprehensive overview is provided for every method, whereas pros and cons are critically analyzed and discussed. Emphasis was given to miniaturized methods which are more consistent with the principles of “green analytical chemistry”.

Is pinking susceptibility index a good predictor of white wines pinking phenomena?

The concentration of anthocyanins in white wines from different grape varieties (Prosecco, Sauvignon Blanc, Pinot Grey, Chardonnay, Síria) from diverse countries (Italy, Moldova, and Portugal) was determined. Anthocyanins, mainly malvidin-3-O-glucoside, were detected in all wines (from 0.7 to 704 μg/L). No correlation between anthocyanins concentration and the Pinking Susceptibility Index (PSI) was observed contrarily to the colour of wines exposed to oxygen (r = 0.871, p < 0.00005). The oxidation of wines with hydrogen peroxide resulted in the formation of various compounds. PSI was correlated with compounds absorbing in the 400-480 nm region, probably more related to the browning than the pinking phenomenon. The lack of correlation between the PSI and anthocyanins concentration in white wines can be due to the different chemical compositions of white wines that yield various compounds after oxidation that might not be related to the natural wine pinking phenomenon.

Ensuring the preservation of the quality of wine during storage

The article presents the necessity for a detailed approach to the choice of packaging for wine, as well as assessing their quality level. It has been established that the transformation of the component composition of wine proceeds with different intensity depending on the type of packaging and leads to different consequences, mainly due to the occurrence of redox reactions, as well as the degree of gas exchange during storage. Complex packaging "package in a box" can become a source of premature oxidation of wines and the appearance of foreign synthetic inclusions in them.

Comparison of a Rapid Light-Induced and Forced Test to Study the Oxidative Stability of White Wines

The oxidation processes of white wines can occur during storage and commercialization due to several factors, and these can negatively affect the color, aroma, and quality of the wine. Wineries should have faster and simpler methods that provide valuable information on oxidation stability of wines and allow fast decision-making procedures, able to trigger suitable technological interventions. Using a portable prototype instrument for light irradiations at different wavelengths and times was considered and evaluated on sensorial, spectrophotometric, and colorimetric parameters of white wines. The sensorial analysis revealed that white and light blue were the most significant, after only 1 h of irradiation. The experimental results showed that hydrogen peroxide could enhance the effect of light treatment, allowing a contemporary evaluation of the oxidation stability of wine against light and chemical stresses. As expected, a good correlation (R² > 0.89) between optical density at 420 nm and b* parameter was highlighted. The synergic effect of light and H₂O₂ was also studied on the hydrolyzable and condensed tannins' additions to white wine. The proposed methodology could be used to evaluate the oxidative stability of white wines, but also to evaluate the effect of some oenological adjuvants on wine stability.

Novel styrylbenzimidazolium-based fluorescent probe for reactive sulfur species: Selectively distinguishing between bisulfite and thiol amino acids

In this study, a new fluorescent probe containing dicyanovinyl moiety has been designed and synthesized. Fluorescent probe based on styrylbenzimidazolium derivative was reported for the effective detection of bisulfite and distinguish it from biothiols by exploiting dicyanovinyl group as the recognition site. The photophysical properties of the novel styrylbenzimidazolium derivative were assessed by determination of absorption and fluorescence spectra, fluorescence quantum yield, and fluorescence lifetime. Its spectroscopic behavior towards various analytes has been evaluated in aqueous media at a pH of 7.4. The highest increase in fluorescence intensity of compound 5 in the presence of different analytes was observed for sodium bisulfite and the limit of detection was estimated to be 0.25 μM. The styrylbenzimidazolium dye was applied to detect bisulfite in various wine sample using fluorimetry. Finally, the ability of this novel probe to detect HSO₃^- in red wine samples was evaluated.