Precursors consumption preferences and thiol release capacity of the wine yeasts Saccharomyces cerevisiae, Torulaspora delbrueckii, and Lachancea thermotolerans

The aromatic profile of wine determines its overall final quality, and among the volatile molecules that define it, varietal thiols are responsible for shaping the distinctive character of certain wine varieties. In grape must, these thiols are conjugated to amino acids or small peptides in a non-volatile form. During wine fermentation, yeasts play a principal role in expressing these aromatic compounds as they internalise and cleavage these precursors, releasing the corresponding free and aroma-impacting fraction. Here, we investigate the impact of three wine yeasts (Saccharomyces cerevisiae, Torulaspora delbrueckii and Lachancea thermotolerans) on thiol releasing in synthetic grape must fermentations supplemented with different cysteinylated (Cys-4MSP and Cys-3SH) and glutathionylated (GSH-4MSP and GSH-3SH) precursors. We demonstrate higher consumption levels of cysteinylated precursors, and consequently, higher amounts of thiols are released from them compared to glutathionylated ones. We also report a significant impact of yeast inoculated on the final thiols released. Meanwhile T. delkbrueckii exhibits a great 3SHA releasing capacity, L. thermotolerans stands out because of its high 3SH release. We also highlight the synergic effect of the co-inoculation strategy, especially relevant in the case of S. cerevisiae and L. thermotolerans mixed fermentation, that has an outstanding release of 4MSP thiol. Although our results stem from a specific experimental approach that differs from real winemaking situations, these findings reveal the potential of unravelling the specific role of different yeast species, thiol precursors and their interaction, to improve wine production processes in the context of wine aroma enhancement.

Chemosensory analysis of emotional wines: Merging of explicit and implicit methods to measure emotions aroused by red wines

Wine is a cultural product capable of arousing emotions. Measuring emotions and figuring out how much they could influence preferences or purchase decisions of consumers is a new trend in sensory and consumer research. However, the complexity of feelings makes the measure of emotions extremely challenging. Thus, a comprehensive understanding of emotions related to sensory stimuli in wine tasting is still missing. The purpose of the study is to evaluate the emotional power of tasting red wines using a multidisciplinary approach, combining sensory analysis performed by trained panelists, implicit and explicit measurements of emotions and chemical analysis of the wines tasted. Various red wines, renowned for their high polyphenol content and expected to exhibit rich texture, mouthfeel, and aging potential, have been utilized to this extent. The results obtained showed that the emotions measured were well-correlated with quantitative and hedonic attributes obtained using classic sensory analysis. Some aromatic molecules can be identified as markers capable of eliciting positive and negative emotional reactions. While increasing literature in the topic is recently available, our study appears to be the first highlighting the presence of autonomic nervous system (ANS) differences verified by means of electrocardiogram (ECG) features, related to explicit and complete sensory patterns, in response to sensory stimuli related to emotional wine, with higher sympathetic values at extrema and vagal increase in the presence of neutral sensory compounds.

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.

Overview of the distinctive characteristics of strawberry, raspberry, and blueberry in berries, berry wines, and berry spirits

Red berries have gained popularity as functional and nutritious food due to their health benefits, leading to increased consumer demand and higher production, totaling over 11,000 ktons for strawberries, raspberries, and blueberries combined in 2021. Nutritionally, strawberries, raspberries, and blueberries present high levels of vitamin C (9.7-58.8 mg/100 g dry weight [dw]), folates (6-24 µg/100 g dw), and minerals (96-228 mg/100 g dw). Due to their perishable nature, producers have utilized alcoholic fermentation to extend their shelf life, not only increasing the lifespan of red berries but also attracting consumers through the production of novel beverages. Strawberry, blueberry, and raspberry wines possess low alcohol (5.5-11.1% v/v), high acidity (3.2-17.6 g/L), and interesting bioactive molecules such as phenolic compounds, carotenoids, polysaccharides, and melatonin. Distillation holds tremendous potential for reducing food waste by creating red berry spirits of exceptional quality. Although research on red berry spirits is still in the early stages, future studies should focus on their production and characterization. By incorporating these factors, the production chain would become more sustainable, profitable, and efficient by reducing food waste, capitalizing on consumer acceptance, and leveraging the natural health-promoting characteristics of these products. Therefore, this review aims to provide a comprehensive overview of the characteristics of strawberry, blueberry, and red raspberry in berries, wines, and spirits, with a focus on their chemical composition and production methods.

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.

Sensory evaluation of Protected Designation of origin Wines: Development of olfactive descriptive profile and references

Wines covered by PDO or PGI quality labels have specific sensory characteristics. According to EU regulations, product characteristics (including the sensory description) must be defined in the PDO technical specification and should be verified for their compliance. There exist internationally harmonized quantitative descriptive sensory methods applied to products such as virgin olive oil, with well-defined attributes described in the method itself. Currently, in the case of wine, there is no harmonized international sensory descriptive method that allows comparison of results between different PDOs or laboratories. In this work, a qualitative and quantitative olfactory profile for a broad variety of wines (11 PDO and 37 wine types) and their corresponding reference standards are proposed. The sensory profile obtained can be used both to verify compliance with the technical specifications of the product and to categorize wines by type or region, thus becoming a powerful tool for the wine sector.

Exploring the effects of mixture composition factors and perceptual interactions on the perception of icewine odor: An olfactometer-based study

The perception of food odor, derived from complex mixtures of odorants, remains poorly understood. This study investigated how key odorants of icewine influence odor mixture perception and mixture-induced perceptual interactions. A multichannel olfactometer was used to deliver 90 mixtures to 36 trained participants who used a Rate-All-That-Apply method to rate the odor samples. Results showed that adding odorants to a mixture affected both the characteristic odor of the individual component and other odor characteristics, revealing specific perceptual interactions. Combining up to six odorants with icewine odor influenced a maximum of two odor characteristics in the mixture, regardless of the specific combination. Interestingly, adding odorants had a stronger impact on the overall mixture odor profile than omitting them, particularly when manipulating fewer than three odorants. These findings emphasize the complexity of odor mixture perception and provide new insights into the influence of key odorants on the aroma of wine.

Optimizing the identification of thiols in red wines using new oak-wood accelerated reductive treatment

This study proposes a new method for identifying thiols in red wines by mimicking specific chemical mechanisms that occur during bottle-aging. It involves the reaction of oak-wood extracts with hydrogen sulfide and the reduction of disulfides with DIBAL. After optimization of the reaction conditions, the aroma of fresh oak wood turned into intense "meaty" nuances reminiscent of the aging bouquet of red wines. Samples were analyzed by gas chromatography coupled with olfactometry (GC-O) and coupled with a pulsed flame photometric detector. This resulted in the identification of six odorant zones with meaty descriptors associated with sulfur compounds. One of the odorant zones was identified as 2-methoxybenzenethiol by using heart-cutting multidimensional GC coupled with olfactometry and time of flight mass spectrometer. Its identification in aged red wines was confirmed by GC coupled with tandem mass spectrometry analyses. Five other thiols associated with oak-wood precursors were also identified in red wines.

Convolution Neural Network-Assisted Smart Fluorescent-Tongue Based on Lanthanide Ion-Induced Forming MOF/HOF Composite for Differentiation of Flavor Compounds and Wine Identification

Wine flavor is a vital quality characteristic in wine, influenced by those flavor components with low sensory thresholds. It is crucial to recognize and classify the wine components related to their flavor contribution. The integration of fluorescent sensors and artificial intelligence shows huge potential in flavor recognition by emulation of the gustatory perception system. Meanwhile, achieving information identification of wine based on multiple information barcodes has hopeful applications in anticounterfeiting. In this study, we present a simple method in which organic linkers are weaved into a hydrogen-bonded organic framework (HOF) for the available transformation of a metal-bonded organic framework (MOF) induced by lanthanide ions (Ln3+). The fluorescent Ln-MOF/HOF composite exhibits high sensitivity, rapid response, and good recyclability for detecting seven flavor compounds in wine, including tannic acid, ionone, vanillin, anethole, anisaldehyde, hydroxybenzaldehyde, and 4-hydroxy-2-methylacetophenone. Depending on its satisfactory detectability, a novel strategy is provided in which a fluorescent sensor is able to function as a smart fluorescent-tongue (F-tongue) by the aid of convolutional neural network to differentiate these seven flavor compounds. In addition, the Ln-MOF/HOF composite has been used to prepare multiple information barcodes for wine information identification on the basis of dynamic fluorescence response toward tannic acid. The mimetic gustatory perception system developed in this study may offer a promising strategy for flavor recognition in food and further food anticounterfeiting.

Typical Aroma of Merlot Dry Red Wine from Eastern Foothill of Helan Mountain in Ningxia, China

Aroma is an important aspect of wine quality and consumer appreciation. The volatile organic compounds (VOCs) and olfactory profiles of Merlot dry red wines from the Eastern Foothill of Helan Mountain (EFHM) were analyzed using gas chromatography-mass spectrometry and quantitative descriptive analysis. The results showed that Merlot wines from EFHM were characterized by intense flavors of drupe and tropical fruits compared with the Gansu region. Nineteen VOCs were defined as essential compounds contributing to the aroma characteristics of the Merlot wines through gas chromatography-olfactometry/mass spectrometry and odor activity value analysis. Predominantly, geranyl isovalerate, which contributed to the herbal odors of the Merlot wines, was detected in the grape wine of EFHM for the first time. The addition experiment revealed that geranyl isovalerate influenced the aroma quality of wine by increasing herbal odors and enhancing the olfactory intensities of tropical fruits. These results are helpful for further understanding the aroma of Merlot wines from EFHM and improving the quality of wine aromas.

Comparing the Volatile and Soluble Profiles of Fermented and Integrated Chinese Bayberry Wine with HS-SPME GC-MS and UHPLC Q-TOF

To evaluate the flavor characteristics of Chinese bayberry alcoholic beverages, fermented bayberry wine (FBW) and integrated bayberry wine (IBW) were investigated for their volatile and soluble profiles using HS-SPME GC-MS and UHPLC Q-TOF and were analyzed with multidimensional statistical analysis, including PCA and OPLS-DA. The volatile compounds 1-pentanol, β-caryophyllene and isopentanol were only detected in IBW. β-caryophyllene, the key flavor component of bayberry, was found to be the most abundant volatile compound in IBW (25.89%) and was 3.73 times more abundant in IBW than in FBW. The levels of ethyl octanoate, ethyl nonanoate, and ethyl decanoate were also several times higher in IBW than in FBW. These compounds contributed to the strong bayberry aroma and better fruity flavor of IBW. On the other hand, high levels of ethyl acetate and octanoic acid in FBW, representing pineapple/overripe or sweat odor, were key contributors to the fermented flavor of FBW. Soluble sugars, such as sucrose, D-glucose, and D-tagatose, as well as amino acids, such as L-glutamate and L-aspartate, had much higher levels in IBW. The anthocyanin pigment cyanidin 3-glucoside, which generates red color, was also higher in IBW. On the other hand, most of the differentially expressed alcohols, acids, amino acids, purines/pyrimidines and esters were present in higher concentrations in FBW compared to IBW. This demonstrated that IBW has a much sweeter and more savory taste as well as a better color generated by more anthocyanins, while FBW presents a more acidic and drier taste as well as a complex formation of alcohols and esters. The study also prompts the need for further research on the flavor profiles of IBW and its potential application and market value.

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”.

Changes in the Major Odorants of Grape Juice during Manufacturing of Dornfelder Red Wine

Application of the aroma extract dilution analysis (AEDA) on a distillate prepared from freshly squeezed juice of Dornfelder grapes revealed (3Z)-hex-3-enal and trans-4,5-epoxy-(2E)-dec-2-enal with the highest flavor dilution (FD) factors. In contrast, in the final Dornfelder wine prepared thereof, the highest FD factors were found for 2-phenylethyl acetate, 2-phenylethan-1-ol, and (E)-β-damascenone. However, for example, among others, (3Z)-hex-3-enal no longer appeared as an important odorant. To monitor the olfactory changes occurring in single processing steps from Dornfelder grapes to the final wine, selected odorants in grape juice, must, and young as well as aged wine from the same batch of Dornfelder grapes were quantitated. In particular, (3Z)-hex-3-enal and hexanal decreased considerably during mashing, while, as to be expected, the concentrations of yeast metabolites, e.g., odor-active alcohols and esters, drastically increased during fermentation. To reveal the influence of barrel aging, the odorants of the same Dornfelder wine aged in either barrique barrels or steel tanks were compared.

Development of a Descriptive Profile and References for the Assessment of Taste and Mouthfeel Descriptors of Protected Designation of Origin Wines

Producers of PDO (Protected Designation of Origin) wines must submit to the EU authorities’ technical specifications that include the specific sensory description of each product typology, to be subsequently checked by the competent authority in each country. Unfortunately, there is no consensual and standardized approach for the development of sensory control methods for PDO wines. The aim of this work was to develop a sensory profile for the taste and mouthfeel descriptors that allows the characterization of wines from 11 existing PDOs in Catalonia (Spain), and with the purpose of advancing the process of harmonization of the official sensory analysis of wines. This paper includes the selection process of tasters, the procedure used for the definition and grouping of descriptors, and the development of references for the selected attributes. The use of this analytical tool should allow PDO/PGI product certification and control authorities to verify compliance with their specifications (descriptive and quantitative) based on objectively evaluated results.

Comparative Metabolite Fingerprinting of Four Different Cinnamon Species Analyzed via UPLC-MS and GC-MS and Chemometric Tools

The present study aimed to assess metabolites heterogeneity among four major Cinnamomum species, including true cinnamon (Cinnamomum verum) and less explored species (C. cassia, C. iners, and C. tamala). UPLC-MS led to the annotation of 74 secondary metabolites belonging to different classes, including phenolic acids, tannins, flavonoids, and lignans. A new proanthocyanidin was identified for the first time in C. tamala, along with several glycosylated flavonoid and dicarboxylic fatty acids reported for the first time in cinnamon. Multivariate data analyses revealed, for cinnamates, an abundance in C. verum versus procyandins, dihydro-coumaroylglycosides, and coumarin in C. cassia. A total of 51 primary metabolites were detected using GC-MS analysis encompassing different classes, viz. sugars, fatty acids, and sugar alcohols, with true cinnamon from Malaysia suggested as a good sugar source for diabetic patients. Glycerol in C. tamala, erythritol in C. iners, and glucose and fructose in C. verum from Malaysia were major metabolites contributing to the discrimination among species.

Assessing the contribution of odor-active compounds in icewine considering odor mixture-induced interactions through gas chromatography-olfactometry and Olfactoscan

The sensory impact of odor-active compounds on icewine aroma could be influenced by perceptual interactions with other odor-active compounds. The aim of this study was to establish an approach to evaluate the contribution of odor-active compounds found in icewine considering mixture-induced perceptual interactions. By comparing the impact of key odorants detected in icewine following a gas chromatography-olfactometry approach with an Olfactoscan-based methodology using a background odor of icewine, 69 odor zones were detected, and their related compounds were further identified. The results revealed that icewine background odor could exert odor masking or enhancement on key odorants when they are considered in the complex wine aroma buffer. Several compounds can induce qualitative changes in the overall wine aroma. This study underlined the efficiency of Olfactoscan-like approaches to screen for the real impact of key odorants and to pinpoint specific compounds that could be highly influential once embedded in the aroma buffer.

Formation, Losses, Preservation and Recovery of Aroma Compounds in the Winemaking Process

A wine’s aroma profile is an important part of the criteria affecting wine acceptability by consumers. Its characterisation is complex because volatile molecules usually belong to different classes such as alcohols, esters, aldehydes, acids, terpenes, phenols and lactones with a wide range of polarity, concentrations and undesirable off-aromas. This review focused on mechanisms and conditions of the formation of individual aroma compounds in wine such as esters and higher alcohols by yeast during fermentation. Additionally, aroma losses during fermentation are currently the subject of many studies because they can lead to a reduction in wine quality. Principles of aroma losses, their prevention and recovery techniques are described in this review.

Volatile Composition and Sensory Characterisation of Dry White Wines Made with Overripe Grapes by Means of Two Different Techniques

Grape over-ripening is a technique that has historically been used for the production of white wines in southern Spain. However, this technique is still widely used for the production of sweet wines. In this study and after recently proving the feasibility of making dry white wines from overripe grapes with and without the presence of grape skin in a warm climate zone, the sensory characterization and analysis of the major and minor volatile compounds in dry white wines made from overripe grapes are presented for the first time. Two over-ripening techniques (sun-drying and climatic chamber drying) were studied for two different periods of time (48 and 96 h), as has the presence of grape skins during alcoholic fermentation. Grape over-ripening implies modifications in the composition of both the major and minor volatile compounds in wines. In terms of sensory analysis, wines with a similar profile were obtained year-on-year. The results of the preference test show that the wines made from grapes that had been over-ripened in the sun for 96 h were preferred by the tasting panel for both vintages. Thus, grape over-ripening under the sun could be considered as a resilience and adaptation technique for increased temperature conditions during the ripening season caused by the effects of climate change.

Optimization of SPME-Arrow-GC/MS Method for Determination of Free and Bound Volatile Organic Compounds from Grape Skins

(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples.

Effects of different vinification technologies and yeasts on qualitative parameters and terpene compounds of Sauvignon Blanc wines

Sauvignon Blanc represents an important grape variety. The wine made from this variety is known to have a wide range of aroma profiles from nettles to tropical fruits. Beside the raw material quality (grapes), the quality of wines can be fundamentally influenced by the technological conditions applied in the wine making process. Yeast and other microorganisms play a key role in the formation of metabolites during alcoholic fermentation. In this study, the effects of autochthonous or selected wine yeasts (Saccharomyces cerevisiae) and fermentation temperatures (15 °C and 19 °C) were tested on major monoterpenes contents of wines during the period 2016–2017. The obtained values show that the highest contents of linalool (24.36 μg L−1) and hotrienol (11.84 μg L−1) were determined in wine samples produced with active (selected) wine yeast at lower temperature. Sensory evaluation results indicated that monoterpenes can have a positive effect on the overall sensory quality of Sauvignon Blanc wines, despite the fact that their determined concentrations in the evaluated samples were not higher than their threshold values.

Comparison of Potent Odorants in Traditional and Modern Types of Chinese Xiaoqu Liquor (Baijiu) Based on Odor Activity Values and Multivariate Analyses

Predominant odorants in modern and traditional types of Chinese xiaoqu liquor (Baijiu) were identified and compared by the combined use of gas chromatography−olfactometry, odor activity values (OAVs), and multivariate analyses. A total of 79 aroma compounds were identified in a typical modern type xiaoqu Baijiu (M) and a typical traditional type xiaoqu Baijiu (T), 42 of them had OAV > 1 in both M and T samples. The main differences between the two samples were obtained for the concentration of 23 aroma-active compounds. A total of 22 samples made by different brewing processes were analyzed to confirm the differences. Partial least squares discriminant analysis confirmed that 20 compounds could be used as potential markers for discrimination between modern type xiaoqu Baijiu and traditional type xiaoqu Baijiu. Their difference in content is between 1.5 and 17.9 times for modern type xiaoqu Baijiu and traditional type xiaoqu Baijiu. The results showed the aroma characteristics of modern and traditional type xiaoqu Baijiu clearly and comprehensively, which will provide guidance for modern Baijiu quality control and evaluation.

Strategies for the identification and sensory evaluation of volatile constituents in wine

Wine aroma, which stems from complex perceptual and cognitive processes, is initially driven by a multitude of naturally occurring volatile constituents. Its interpretation depends on the characterization of relevant volatile constituents. With large numbers of volatile constituents already identified, the search for unknown volatiles in wine has become increasingly challenging. However, the opportunities to discover unknown volatile compounds contributing to the wine volatilome are still of great interest, as demonstrated by the recent identification of highly odorous trace (µg/L) to ultra-trace (ng/L) volatile compounds in wine. This review provides an overview of both existing strategies and future directions on identifying unknown volatile constituents in wine. Chemical identification, including sample extraction, fractionation, gas chromatography, olfactometry, and mass spectrometry, is comprehensively covered. In addition, this review also focuses on aspects related to sensory-guided wine selection, authentic reference standards, artifacts and interferences, and the evaluation of the sensory significance of discovered wine volatiles. Powerful key volatile odorants present at ultra-trace levels, for which these analytical approaches have been successfully applied, are discussed. Research areas where novel wine volatiles are likely to be identified are pointed out. The importance of perceptual interaction phenomena is emphasized. Finally, future avenues for the exploration of yet unknown wine volatiles by coupling analytical approaches and sensory evaluation are suggested.

Aroma of Icewine: A Review on How Environmental, Viticultural, and Oenological Factors Affect the Aroma of Icewine

The aroma of a wine is mostly driven by not only the factors in the vineyard, such as the grape variety and harvest time, but also the fermentation process. Icewine is a unique, intensely sweet wine made from late harvested grapes that have frozen naturally on the vine. Different from normal table wines, the grapes used in icewine naturally undergo a dehydration process and freeze-thaw cycles, and the must for icewine making has to be pressed from frozen grapes. This pressing process leaves water behind as ice crystals and allows the grape juice to be concentrated with more sugars, acids, and other dissolved solids, resulting in a slower than normal fermentation. These special procedures can lead to a unique aroma characteristic of icewine. This review delves into recent advances in chemical compounds related to icewine aroma characteristics and addresses how changes in these aroma characteristics and composition are influenced by environmental, viticultural, and oenological factors in the vineyard and winery. Deficiencies in previous studies and future trends related to the flavor science of icewine were also briefly addressed.

Application of untargeted volatile profiling and data driven approaches in wine flavoromics research

Traditional flavor chemistry research usually makes use of targeted approaches by focusing on the detection and quantification of key flavor active metabolites that are present in food and beverages. In the last decade, flavoromics has emerged as an alternative to targeted methods where non-targeted and data driven approaches have been used to determine as many metabolites as possible with the aim to establish relationships among the chemical composition of foods and their sensory properties. Flavoromics has been successfully applied in wine research to gain more insights into the impact of a wide range of flavor active metabolites on wine quality. In this review, we aim to provide an overview of the applications of flavoromics approaches in wine research based on existing literature mainly by focusing on untargeted volatile profiling of wines and how this can be used as a powerful tool to generate novel insights. We highlight the fact that untargeted volatile profiling used in flavoromics approaches ultimately can assist the wine industry to produce different wine styles and to market existing wines appropriately based on consumer preference. In addition to summarizing the main steps involved in untargeted volatile profiling, we also provide an outlook about future perspectives and challenges of wine flavoromics research.

A Comparative Study on Volatile Compounds and Sensory Profile of White and Red Wines Elaborated Using Bee Pollen versus Commercial Activators

Lack of nutrients in grape may cause problems for a proper alcoholic fermentation process, resulting in an altered aromatic profile of the wines. To avoid this situation, commercial winemakers often use fermentation activators, which are usually combinations of ammonium salts, inactivated yeast and thiamine. In addition, it has been shown that bee pollen addition to the grape can help to improve fermentation, resulting in better volatile compound profile of wines responsible for sensory quality. For this reason, the aim of this research work was to carry out a comparative study using bee pollen versus commercial fermentation activators in white and red winemaking. The same dose of bee pollen and commercial activators (0.25 g/L) were used in all experiments. Volatile compounds were analyzed by gas chromatography-mass spectrometry, odor activity values were determined to assess odorant impact of various volatile compound families, and finally a descriptive sensory analysis was carried out. Then, the triangular test and the ranking assay were used to identify perceptible differences as well as preference among the wines elaborated. Compared to commercial activators, bee pollen wines increased volatile compound formation, mainly higher alcohols, esters, and terpenes, enhancing fruity and floral odorant series. On the other hand, triangular test showed significant differences between wines, and the ranking assay showed a greater preference for bee pollen wines.

Minty aroma compounds in red wine: Development of a novel automated HS-SPME-arrow and gas chromatography-tandem mass spectrometry quantification method

A novel automated method was developed for the quantitative determination of nine terpenoids that could contribute to the minty notes of red wine bouquet. The method couples headspace SPME-Arrow extraction with GC-MS/MS analysis. PDMS/DVB fiber was chosen for the extraction and an ionization energy of 30 eV permitted to optimize the analyte detection. The optimal sample preparation consists of a two-fold dilution of the wine sample with addition of 4 g of sodium chloride while the most suitable extraction conditions take place at 50 °C for 1 h. The method shows good linearity, intraday variations between 2 and 25%, interday variations between 7 and 23% and recoveries between 80 and 119%. The method exhibits the required low detection (between 3 and 60 ng/L) and quantification (between 6 ng/L and 200 ng/L) limits. These limits have permitted the quantification of the pool of minty terpenoids in fourteen red Bordeaux wines.

Surface-Enhanced Raman Scattering (SERS) Taster: A Machine-Learning-Driven Multireceptor Platform for Multiplex Profiling of Wine Flavors

Integrating machine learning with surface-enhanced Raman scattering (SERS) accelerates the development of practical sensing devices. Such integration, in combination with direct detection or indirect analyte capturing strategies, is key to achieving high predictive accuracies even in complex matrices. However, in-depth understanding of spectral variations arising from specific chemical interactions is essential to prevent model overfit. Herein, we design a machine-learning-driven "SERS taster" to simultaneously harness useful vibrational information from multiple receptors for enhanced multiplex profiling of five wine flavor molecules at parts-per-million levels. Our receptors employ numerous noncovalent interactions to capture chemical functionalities within flavor molecules. By strategically combining all receptor-flavor SERS spectra, we construct comprehensive "SERS superprofiles" for predictive analytics using chemometrics. We elucidate crucial molecular-level interactions in flavor identification and further demonstrate the differentiation of primary, secondary, and tertiary alcohol functionalities. Our SERS taster also achieves perfect accuracies in multiplex flavor quantification in an artificial wine matrix.

Current Research Related to Wine Sensory Perception Since 2010

Due to socioeconomic changes, the demand for and interest in alcoholic beverages have recently been increasing. Among various alcoholic drinks, consumer preference for wine could be varied. It might be related with its complexity, as wine is known to have characteristics that are difficult to understand. Several factors, such as intrinsic or extrinsic factors interact to influence wine complexity and consumer perception. Many studies have been conducted to understand the complexity of wine, allowing deeper insight into its perception by consumers. Studies over the last decade on wine sensory perception using descriptive analysis and consumer tests were reviewed. Additionally, chemical analysis studies were included because flavor constituents information would contribute to a better understanding of sensory perception. Descriptive sensory analysis of wine was reviewed considering panels and flavor characterization for better understanding wine-related research. Several consumer studies regarding liking/preference, emotion, context, and extrinsic factors to understand consumer preference or perception were reviewed. Research on chemical constituents may affect consumer perception and is thus presented in this review. However, most of the research was focused on a narrow range of wine, thus is missing overall wine category evaluations. Furthermore, evaluations were mainly in wine-producing countries, resulting in limited understanding of an emergent market. This review will help guide wine researchers and industry by providing information on factors influencing consumer wine perception.

Bee Pollen Role in Red Winemaking: Volatile Compounds and Sensory Characteristics of Tintilla de Rota Warm Climate Red Wines

One of the main aspects that define wine quality is its aromatic profile. Nutritional deficiencies in musts can lead to olfactory defects and a decline in quality. Commercial activators and nutrients are usually added to the must in these cases. The natural composition of bee pollen can provide all the necessary nutrients for yeasts. This investigation aims to analyze the impact of pollen addition on the profile of volatile and sensory compounds in Tintilla de Rota warm climate red wines. Volatile compounds were measured by Gas Chromatography–Mass Spectrometry, Odorant Activity Values analysis to find out each compound’s fragrant participation, and sensorial analysis was conducted for a qualified panel of wine-tasters. As a result of the chromatographic analysis, 80 volatile compounds of different chemical families were identified and quantified. Bee pollen increased mainly isoamyl alcohol, esters, and terpenes compounds families in wines. Odorant Activity Values analysis showed an increase in fruity odorant series mainly, followed by floral, for all wines with pollen addition. The sensory analysis showed that low pollen doses (0.1 g/L and 0.25 g/L) increased tasting notes of fruit and floral attributes and fruit and floral odorant series as well, highlighting an increase in red and black fruit notes mainly. On the other hand, high doses deviated the sensory profile towards fleshy stone fruit, and raisin fruit, mostly. In addition, high bee pollen doses produce an increase in the odorant category responsible for the chemical, fatty, and grassy aromas mainly, and high and intermediate dose (1 g/L) an increase in the earthy notes in the aromas. Therefore, low bee pollen doses (0.1 and 0.25 g/L) can improve both the aromatic compound profile, as well as the Odorant Activity Values levels and the sensory profile in Tintilla de Rota red wines.

Identification of key odorants in complex mixtures occurring in nature

Covering: up to 2019Soon after the birth of gas chromatography, mass spectrometry and olfactometry were used as detectors, which allowed impressive development to be achieved in the area of odorant determinations. Since the mid-80s, structured methods of gas chromatography-olfactometry have appeared, allowing the determination of which odor constituents play a key role in materials. Progressively, numerous strategies have been proposed for sample preparation from raw materials, the representativeness evaluation of extracts, the identification of odor constituents, their quantification, and subsequently, the recombination of the key odorants to mimic the initial odor. However, the multiplicity of options at each stage of the analysis leads to a confusing landscape in this field, and thus, the present review aims at critically presenting the available options. For each step, the most frequently used alternatives are described, together with their strengths and weaknesses based on theoretical and experimental justifications according to the literature. These techniques are exemplified by many applications in the literature on aromas, fragrances and essential oils, with the initial focus on wine odorants, followed by a short overview on the molecular diversity of key odorants, which illustrates most of the facets and complexities of odor studies, including the issues raised by odorant interactions such as synergies.

Influence of partial dealcoholization on the composition and sensory properties of Cabernet Sauvignon wines

Worldwide, winemakers are increasingly adopting alcohol management strategies to counter the higher wine ethanol concentrations observed over the past ~30 years. Wines with high ethanol levels exhibit increased 'hotness' on the palate, which is generally considered to negatively impact wine quality. This study investigated changes in the chemical and sensory profiles of five Cabernet Sauvignon wines following their partial dealcoholization by reverse osmosis-evaporative perstraction (RO-EP). Descriptive analysis (DA) of wine before and after RO-EP treatment indicated dealcoholization did not strongly affect wine aroma and flavor, consistent with the small changes observed in wine chemical composition. However, significant differences in the perception of wine palate attributes were observed, with dealcoholized wines found to exhibit lower acidity, sweetness, bitterness, saltiness and/or body. Astringency was enhanced following partial dealcoholization of one wine, but diminished in another. Sensory trials were also undertaken to determine the optimal ethanol concentration of wines, or the 'alcohol sweetspot'. Two approaches to alcohol sweetspotting of dealcoholized wines were evaluated, together with two methods of statistical analysis, chi-squared goodness of fit and one proportion tests.

A matter of place: Sensory and chemical characterisation of fine Australian Chardonnay and Shiraz wines of provenance

Establishing a fine wine image through regional typicality has been of interest to New World wine producing countries like Australia, but previous research mainly involved unoaked experimental wines, which were not reflective of the retail wine market. The regional typicality of commercially available fine Australian wines (FAW) was therefore explored, based on the hypotheses that sensory and chemical composition of varietal fine wines would discriminate by region, and further nuances within region would be explained by drivers of intraregional typicality. Chardonnay wines (2015 vintage) from Margaret River (MR, n = 16) and Yarra Valley (YV, n = 16); and Shiraz wines (2014 vintage) from Barossa Valley (BV, n = 16) and McLaren Vale (MV = 15), were selected for descriptive sensory analysis and underwent profiling of volatiles by gas chromatography-mass spectrometry (GC-MS). For both grape varieties, there was large variability in wine styles among wines from the same GI, such as fruity/crisp vs oaked Chardonnay and oaky/astringent vs savoury Shiraz. Consequently, human intervention seemed to be an important component of regional/sub-regional typicality, which therefore cannot be determined solely on geographic origin of the fruit. Using a combination of sensory markers and volatile profiles allowed the building of regional typicality models, which are promising, however, consumers may not perceive sub-regional differences based on sensory attributes. Undoubtedly, variation of wine styles emerging across wine regions, vintages, and viticultural and winemaking practices needs to be further explored, but this work created a preliminary sensory and volatile map for future research.

Modulating Wine Pleasantness Throughout Wine-Yeast Co-Inoculation or Sequential Inoculation

Wine sensory experience includes flavor, aroma, color, and (for some) even acoustic traits, which impact consumer acceptance. The quality of the wine can be negatively impacted by the presence of off-flavors and aromas, or dubious colors, or sediments present in the bottle or glass, after pouring (coloring matter that precipitates or calcium bitartrate crystals). Flavor profiles of wines are the result of a vast number of variations in vineyard and winery production, including grape selection, winemaker’s knowledge and technique, and tools used to produce wines with a specific flavor. Wine color, besides being provided by the grape varieties, can also be manipulated during the winemaking. One of the most important “tools” for modulating flavor and color in wines is the choice of the yeasts. During alcoholic fermentation, the wine yeasts extract and metabolize compounds from the grape must by modifying grape-derived molecules, producing flavor-active compounds, and promoting the formation of stable pigments by the production and release of fermentative metabolites that affect the formation of vitisin A and B type pyranoanthocyanins. This review covers the role of Saccharomyces and non-Saccharomyces yeasts, as well as lactic acid bacteria, on the perceived flavor and color of wines and the choice that winemakers can make by choosing to perform co-inoculation or sequential inoculation, a choice that will help them to achieve the best performance in enhancing these wine sensory qualities, avoiding spoilage and the production of defective flavor or color compounds.

Comparison of an Offline SPE-GC-MS and Online HS-SPME-GC-MS Method for the Analysis of Volatile Terpenoids in Wine

The aroma profile is an important marker for wine quality. Various classes of compounds are responsible for the aroma of wine, and one such class is terpenoids. In the context of this work, a validated gas chromatography-mass spectrometry (GC-MS) method for the quantitation of terpenoids in red and white wine using headspace solid-phase microextraction (HS-SPME) and solid-phase extraction (SPE) was established. Calibrations were performed in the respective base wine using both sample preparation methods. The linearity, precision and accuracy evaluated for the respective matrices were excellent for both sample preparations. However, the HS-SPME approach was more sensitive and more accurate. For both sample preparations, the quantification limits were lower than the odor thresholds in wine. The terpenoid concentrations (µg/L) were evaluated for 13 white wines using both sample preparation methods. Importantly, the online HS-SPME approach was more sensitive than the offline SPE method. The major terpenoids identified in the white wines evaluated were linalool (0.2-63 µg/L), geraniol (nd-66 µg/L) and α-terpineol (nd-85 µg/L).

Temporal Check-All-That-Apply (TCATA) Reveals Matrix Interaction Effects on Flavor Perception in a Model Wine Matrix

Traditionally, the sensory properties of wine were characterized using a trained panel and descriptive analysis (DA)-a static sensory evaluation method. As wine is a complex mixture, with evolving sensory properties, a way to capture these changes is needed in order to fully describe the sensory experience of wine perception. In this study, temporal check-all-that-apply (TCATA), a dynamic sensory evaluation method, was used to characterize model wine samples reminiscent of a white, hybrid wine. Twelve model wines varied in levels of ethanol, glycerol, and caffeic acid, representing commercial levels in Pennsylvania. Samples were evaluated for up to three minutes by a trained TCATA panel (n = 12) for flavor, taste, and mouthfeel attributes. In general, the experimental factors, ethanol and glycerol, along with interactions between factors, had the greatest temporal effects, with significant differences in flavor attributes occurring within the first 30 seconds of evaluation, while taste and mouthfeel attributes showed significant differences throughout the evaluation period. Overall, ethanol had the greatest impact on temporal wine perception. The findings of this study further suggest that a temporal evaluation method, like TCATA, should be paired with DA to completely characterize a complex and evolving sample. Further, changes in wine matrix components affect sensory perception both in direct and indirect ways-the latter indicated by taste-taste suppression and cross-modal interaction effects.

Influence of Native Saccharomyces cerevisiae Strains from D.O. “Vinos de Madrid” in the Volatile Profile of White Wines

Yeasts during alcoholic fermentation form a vast number of volatile compounds that significantly influence wine character and quality. It is well known that the capacity to form aromatic compounds is dependent on the yeast strain. Thus, the use of native yeast strains, besides promoting biodiversity, encourages the conservation of regional sensory properties. In this work, we studied the volatile profile of Malvar wines fermented with 102 Saccharomyces cerevisiae yeast strains, isolated from vineyards and cellars belonging to the D.O. “Vinos de Madrid”. The wines elaborated with different S. cerevisiae showed a good classification by cellar of origin. Additionally, seven sensory descriptors have helped to classify the wines depending on their predominant aromatic character. Twenty-nine Saccharomyces strains, belonging to five of six cellars in the study, were characterized by producing wines with a fruity/sweet character. Floral, solvent, and herbaceous descriptors are more related to wines elaborated with Saccharomyces strains from organic cellars A, E, and F. Based on these findings, winemakers may use their best native S. cerevisiae strains, which add personality to their wine. Therefore, this study contributes to promoting the use of native Saccharomyces yeasts in winemaking.

Development of an in-mouth headspace sorptive extraction method (HSSE) for oral aroma monitoring and application to wines of different chemical composition

An in-mouth headspace sorptive extraction (HSSE) procedure for the in-mouth volatile sampling of wine aroma compounds during wine tasting has been developed. The procedure is based on the application of a PDMS (polydimethylsiloxane) twister contained inside a tailored made glass tube placed into the headspace of the mouth after rinsing and spitting-off the wine, which is then followed by gas chromatography mass spectrometry analysis (GCMS). Various parameters that might affect the performance of the method (extraction time, aroma concentration) were firstly investigated. Despite the short selected in-mouth extraction time (30 s); the application of the in-mouth HSSE procedure using real wines allowed the detection of >30 volatile compounds from different chemical families in the oral cavity in a single run, and which are also present in the wine at very low concentrations. Additionally, the in-mouth HSSE profile allowed us to distinguish between wines types (with different non-volatile and volatile composition) in a similar way to that when using data from the headspace of the wine (wine-HSSE-GCMS). The simplicity, sensitivity, good repeatability and the easy automatization of this procedure, makes this technique a reliable and feasible tool to determine the chemical and biochemical changes of these compounds in the mouth in real physiological conditions providing useful -in vivo analytical data to better correlate with sensory studies.

Impact of polyphenols on the headspace concentration of aroma compounds in apple cider

BACKGROUND

To study the effect of polyphenols on the release of aroma compounds in apple cider, the impact of (-)-epicatechin, hydrocaffeic acid and phloridzin on volatility of 12 typical aroma compounds was investigated by headspace solid phase microextraction and gas chromatography-mass spectrometry.

RESULTS

Analysis of variance results showed that increased concentrations of the phenolic compounds significantly affected the headspace concentration of most aroma compounds. The three polyphenols induced a volatility decrease for the majority of hydrophobic aroma compounds, while they exhibited an opposite behavior by salting out some hydrophilic alcohols. (-)-Epicatechin and hydrocaffeic acid showed a higher retention effect on most hydrophobic aroma compounds than phloridzin did.

CONCLUSION

This study showed that the polyphenols had varying effects on aroma compound volatility in apple cider. The physicochemical characteristics and spatial conformation of polyphenols and aroma compounds influenced the magnitude of aroma-polyphenol interaction in apple cider. Understanding the effects of polyphenols on aroma release can improve the prediction of aroma profiles through chemical analysis, which assists cidermakers in improving the aroma quality of apple cider. © 2018 Society of Chemical Industry.

Volatile aroma compounds in wines from Chinese wild/hybrid species

The volatile aroma compounds in wines produced from Chinese wild/hybrid species were investigated in comparison to wines from European grapes. Volatiles were extracted by headspace solid-phase micro-extraction and identified by gas-chromatography/mass-spectrometry. The identification of analyte was performed by a combination of the linear retention index approach with the comparison of the obtained mass spectra. A total of 98 peaks were tentatively assigned as wine aroma components, and 15 odorants can be found at concentrations above their odor threshold among the odor activity values (OAVs) of 46 compounds evaluated in all of the wines. The "OAVs' aroma wheels" showed that the classes of aromatic series are first fruity, next herbaceous and roasty and no spicy and caramelized notes. Via principal component analysis, all the grape germplasm studied could be divided into four groups: "Jingsheng-1," "Cabernet Gernischt," "Beibinghong," and others, which exhibited distinctive aroma features, respectively. Practical applications Chinese wild grape species have many desirable properties for wine grape breeding such as possessing strong resistant genes to fungal diseases and cold condition, especially after hybridization with European grapes. As an emerging wine country, wines from Chinese wild/hybrid species have achieved much success in the last few years. The chemical content and biological properties have been studied extensively in many but there are a few studies in our knowledge about the wine tastes of these species. In this paper, the key odorants in wines produced from the Chinese grape species of V. amurensis Rupr., V. davidii Foex., and V. quinquangularis Rehd. and its hybrids were characterized in comparison to wines produced from European grapes (V. vinifera). The findings will help to the further understanding of the key aroma components in the different Chinese grapevine germplasm, and make further efforts to enrich the wine types in the marketplace.