Effect of sugar and acid composition, aroma release, and assessment conditions on aroma enhancement by taste in model wines

Changes in Young Adults' Perception of an Interspecific Hybrid Grape Juice Induced by the Addition of Acid or Sugar as Part of a Novel Diversification Strategy for the Grape Industry

As an alternative to traditional red wine production during an economic crisis, we investigated the sensory perception and appreciation (liking) of young consumers for organic red grape juice from the Plantet cultivar (Seibel 5455) with or without the addition of sugar or organic acid. This was evaluated through four studies involving panels of young adults with an average age of 22 years. The goal was to determine how adding tartaric acid or hexoses (glucose and fructose) affected hedonic scores as well as gustatory and aromatic attributes. Surprisingly, adding acid to a must that experts deemed overly sweet (with 255 g/L of endogenous sugar in the control) did not improve liking scores. Similarly, the addition of hexoses did not enhance liking. Instead, natural grape juice, without any added sugar or acid, was the most preferred product among the young adult panelists. This preference was shared by a panel of enology students, who can be considered future key decision makers in the wine and juice industries, in the last study. As expected, the addition of hexoses led to a perception of 'jam' and 'sweet' attributes, while the addition of tartaric acid resulted in a more 'acidic' profile. Interestingly, the fruit attributes most associated with hexose addition were 'apricot' and 'strawberry', whereas tartaric acid addition was most strongly associated with 'raspberry'.

Olfactory perception complexity induced by key odorants perceptual interactions of alcoholic beverages: Wine as a focus case example

The odorants in alcoholic beverages are frequently experienced as complex mixtures, and there is a complex array of influence factors and interactions involved during consumption that deeply increase its olfactory perception complexity, especially the complexity induced by perceptual interactions between different odorants. In this review, the effect of olfactory perceptual interactions and other factors related to the complexity of olfactory perception of alcoholic beverages are discussed. The classification, influencing factors, and mechanisms of olfactory perceptual interactions are outlined. Recent research progress as well as the methodologies applied in these studies on perceptual interactions between odorants observed in representative alcoholic beverages, especially wine, are briefly summarized. In the future, unified theory or systematic research methodology need to be established, since up to now, the rules of perceptual interaction between multiple odorants, which is critical to the alcoholic beverage industry to improve the flavor of their products, are still not revealed.

Characterization of the key odorants in goji wines in three levels of sweetness by applications of sensomics approach

The correlations and differences of the key odorants were systematically conducted among three sweetness of goji wines by the sensomics approach. After aroma (extract) dilution analysis, 67, 67, and 66 odorants were screened in sweet goji wine, semi-dry goji wine, and dry goji wine, in which, 63 odorants were identified in all goji wines. Determination of 53 odorants revealed a total of 30 odorants with the concentrations surpassing their olfactory thresholds. Overall, the odor activity values (OAVs) of ketones decreased, while esters, alcohols, phenols, and aldehydes increased with the decrease in sweetness in goji wine samples. Nevertheless, (E)-β-damascenone, trans- and cis-whisky lactones, and 3-methyl-2,4-nonanedione, evoked cooked apple-like, coconut-like, and hay-like odor impressions in goji wines and showed the highest OAVs. A reliable evaluation of the aroma contributions was executed as aroma recombinations and suggested a successful evaluation of key odorants in goji wines.

Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines

Coffee pulp wines were produced through the mixed fermentation of Saccharomyces cerevisiae, and the flavor and sensory characteristics were comparatively evaluated. A total of 87 volatile components were identified from five coffee pulp wines, of which 68 were present in all samples, accounting for over 99% of the total concentration. The sample fermented contained significantly higher levels of volatile metabolites (56.80 mg/g). Alcohols (22 species) and esters (26 species) were the main flavor components, with the contents accounting for 56.45 ± 3.93% and 31.18 ± 4.24%, respectively, of the total. Furthermore, 14 characteristic components were identified as potential odor-active compounds, contributing to sweet and floral apple brandy flavor. Although the characteristic components are similar, the difference in the content makes the overall sensory evaluation of the samples different. The samples formed by fermentation of four strains, which obtained the highest score (86.46 ± 0.36) in sensory evaluation, were further interpreted and demonstrated through the Mantel test. The results of the component analysis were effectively distinguished by OPLS-DA and PCA, and this validation was supported by sensory evaluation. The research results provided a technical reference for the production of coffee pulp wines.

Advances in the Application of Direct Injection Mass Spectrometry Techniques to the Analysis of Grape, Wine and Other Alcoholic Beverages

Direct injection mass spectrometry (DIMS) entails the direct introduction of a gaseous sample into a mass analyser without prior treatment or separation. DIMS techniques offer the opportunity to monitor processes in time, with limits of detection as low as 0.5 parts per trillion in volume (for a 1 s measurement time) while providing results with high informational content. This review provides insight into current and promising future developments of DIMS in the analysis of grape, wine and other alcoholic beverages. Thanks to its unique characteristics, DIMS allows the online monitoring of volatile organic compounds (VOCs) released by grapes during fermentative bioprocesses or by wine directly from the glass headspace or during drinking. A DIMS-based approach can also be adopted to perform quality control and high-throughput analysis, allowing us to characterise the volatile profile of large sample sets rapidly and in a comprehensive fashion. Furthermore, DIMS presents several characteristic elements of green analytical chemistry approaches, catalysing an interest linked to the development of sustainable paths in research and development activities in the field of viticulture and oenology.

Sequential culture with aroma-producing yeast strains to improve the quality of Kyoho wine

Despite many non-Saccharomyces yeasts being considered spoilage microorganisms, they can increase aroma and flavor diversity in alcoholic beverages. The purpose of this study was to investigate nontraditional inoculation strategies using aroma-producing yeast strains for Kyoho wine fermentation, followed by an instrumental analysis and sensory evaluation. The winemaking process was carried out using Saccharomyces cerevisiae Gr112, Hanseniaspora uvarum Pi235, and Pichia kluyveri Pe114. Multiple inoculation strategies were explored. In instrumental analysis results, mixed culture could promote the formation of esters (5.9-folds) and glycerol (1.3-folds) and reduce the content of ethanol (-0.5% [v/v]) in wine. The sensory analysis results suggested that the three yeast strains sequential inoculation treatment was associated with the aroma attributes "floral," "red fruity," and "tropical fruity." Co-cultivation contributed to an increase in complexity and aromatic intensity, with the three-strain inoculation treatment presenting a more distinctive appearance. PRACTICAL APPLICATION: The inoculation of S. cerevisiae improved the accumulation of volatile acids and esters by inhibiting the growth of non-Saccharomyces yeast strains. Inoculation of H. uvarum and P. kluyveri would effectively solve the defect of excessive content of higher alcohols in wines produced by S. cerevisiae. The suitable inoculation strategy between non-Saccharomyces yeasts could improve the overall quality of Kyoho wine whose starter might be widely used in fermentation industry.

Effects of Organic Acids on the Release of Fruity Esters in Water: An Insight at the Molecular Level

It is well known that organic acids (OAs) could affect the flavour of fruit juices and beverages. However, the molecular mechanism of aroma release is still unclear. In this study, the effects of citric acid (CA), L-(-)-malic acid (MA) and L-lactic acid (LA) on the release of six selected esters and their sensory perception were investigated by means of HS-GC-MS analyses and odour detection threshold determination, respectively. Meanwhile, the density functional theory (DFT) calculation was employed to explore the interaction modes between esters and OAs. HS-GC-MS analyses showed that the concentration and the type of OAs regulated the release of esters. The results were basically consistent with the detection threshold change of those esters. The DFT calculation suggested that the main intermolecular interaction was hydrogen bonds, and several esters could form a ternary ring structure with OAs through hydrogen bonds. The interactions can induce the different release behaviours of esters in OAs water solution. The number of carboxyl functional groups in OAs and the spatial conformation of esters appeared to influence the magnitude of the interaction. The above results demonstrated the mechanism of OAs affecting the release of esters and indicated a possible flavour control way by using different OAs and OA concentrations.

The implication of phenolic acid matrix effect on the volatility of ethyl acetate in alcohol-free wine model: Investigations with experimental and theoretical methods

Hydroxycinnamic acids and ethyl acetate were assessed in simulated alcohol-free wine solutions to explore the effect of phenolic acids on the aroma volatility of esters. The results showed that the phenolic acids could inhibit the volatilization of ethyl acetate, and the extent of inhibition was influenced by the concentration and structure of the phenolic compounds. The ultraviolet absorption spectra of the phenolic acids and ethyl acetate confirmed the interaction between the two compounds. The thermodynamic parameters of the interaction implied a spontaneous exothermic interaction, driven primarily by hydrophobic effects. Meanwhile, the results of the fluorescence-quenching analysis indicated electron transfer between the reactants. The quantum chemical investigations revealed negative and positive charge density distributions in the structures of ethyl acetate and the phenolic acids, respectively. These results will provide some data reference and theoretical support for further research on the effects of phenolic acid matrix on other structural esters.

Characterisation of key odorants causing honey aroma in Feng-flavour Baijiu during the 17-year ageing process by multivariate analysis combined with foodomics

Honey aroma is a typical sensory characteristic of Feng-flavour Baijiu, which originates from a unique manufacturing process, the formation mechanism of which is unclear. Multivariate analysis combined with foodomics assisted by sensory evaluation was performed to investigate the molecular mechanism of honey aroma formation in Feng-flavour Baijiu during the 17-year ageing process. A total of 1995 compounds was identified, and 47 variables were screened as significant substances according to variable importance in projection and Spearman's rank correlation coefficient (|ρ| > 0.7), which corroborated that the long-term interaction between Baijiu and storage containers was the dominant origin of honey aroma. Recombination and omission experiments further validated the important contributions of significant substances, including acids, alcohols, aldehydes and ketones. A typical honey aroma dominated by fruity, floral, sweet and nutty notes was successfully simulated, and nutty notes could be enhanced by amides, whereas amines presented masking effects on fruity and floral aromas.

Characterization of sensory perceptions elicited by white wine spiked with different aroma, taste and mouth-feel active molecules

The present work was aimed at understanding the sensory responses induced by dry white wine modified with increasing concentrations of different sensory active molecules. The tasting panel was composed by 34 trained subjects characterized according to gender, smoking habits, 6-n-propylthiouracil (PROP) taster status, and sensitivity to tartaric acid, tannic acid and sucrose. Additional taste/mouthfeel responsiveness was evaluated in a basal white wine added of tartaric acid, tannic acid and sucrose. The addition of a fruity odorant mixture to the base white wine enabled the assessment of orthonasal aroma and taste intensities (sweetness, sourness, saltiness). The diversity of taste/mouthfeel responsiveness in water or wine enabled to group individuals as high or low sensitives. Likewise, the tasting panel showed two groups responding differently to aroma and flavor. Both high and low aroma sensitivity individuals showed equal (p>0.05) and congruent response to in-mouth sweet flavor perception. Moreover, the high smell sensitive group was less sensitive to sourness and saltiness than the low smell sensitives for the spiked wines across all flavor concentrations. Differences in PROP taster status and sensitivity to other tastants in water solutions were not correlated with the taste/mouthfeel perceptions in wine. The individuals most sensitive to sucrose in wine taste showed higher response to the fruity aroma. In conclusion, taste, mouthfeel and flavor perceptions showed a high variability among individuals evidencing the advantage of grouping tasters with different chemosensory sensitivities to understand cross-modal sensory interactions.

Discrimination of French wine brandy origin by PTR-MS headspace analysis using ethanol ionization and sensory assessment

The headspace volatile organic compound (VOC) fingerprints (volatilome) of French wine brandies were investigated by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). Protonated ethanol chemical ionization was used with dedicated experimental conditions that were previously validated for model wines. These included a reference vial containing a hydro-alcoholic solution with the same ethanol content (20% v/v) as the diluted sample spirits, which was used to establish steady-state ionization conditions. A low electric field strength to number density ratio E/N (85 Td) was used in the drift tube in order to limit the fragmentation of the protonated analytes. The obtained headspace fingerprints were used to investigate the origin of French brandies produced within a limited geographic production area. Brandies of two different vintages (one freshly distilled and one aged for 14 years in French oak barrels) were successfully classified according to their growth areas using unsupervised (principal component analysis, PCA) and supervised (partial least squares regression discriminant analysis, PLS-DA) multivariate analyses. The models obtained by PLS-DA allowed the identification of discriminant volatile compounds that were mainly characterised as key aroma compounds of wine brandies. The discrimination was supported by sensory evaluation conducted with free sorting tasks. The results showed that this ethanol ionization method was suitable for direct headspace analysis of brandies. They also demonstrated its ability to distinguish French brandies according to their growth areas, and this effect on brandy VOC composition was confirmed at a perceptive level.

Aroma release during wine consumption: Factors and analytical approaches

During wine consumption, aroma compounds are released from the wine matrix and are transported to the olfactory receptor in vivo, leading to retronasal perception which can affect consumer acceptance. During this process, in addition to the influence of the wine matrix compositions, some physiological factors can significantly influence aroma release leading to altered concentrations of the aroma compounds that reach the receptors. Therefore, this review is focused on the impact of multiple factors, including the physiology and wine matrix, on the aroma released during wine tasting. Moreover, to reflect the pattern of volatiles that reach the olfactory receptors during wine consumption, some analytical approaches have been described for in vitro and in vivo conditions.

Effect of aroma perception on taste and mouthfeel dimensions of red wines: Correlation of sensory and chemical measurements

The present study was aimed at increasing the understanding of red wine mouthfeel by investigating the potential cross-modal effect of aroma and establishing relationships between sensory dimensions and chemical measurements. Investigations involved a set of 42 non-wooded red wines that were described with a novel application of a variant of the rate-all-that-apply sensory methodology ("rate-K attributes") by a group of Spanish wine experts under two conditions: (1) with no aroma perception (using nose clips) and (2) with aroma perception. In parallel, ethanol content, pH, titratable acidity, tannin activity, concentration of tannins, and spectroscopic measures of wines were determined. Results suggest that aroma does not play a main effect on taste or mouthfeel perception of red wines, except for oily mouthfeel, which was hypothesised to be masked by earthy aromas and enhanced by alcoholic nuances attributed to cognitive interactions. Independent and non-correlated mouthfeel dimensions such as dry/silky and sticky, grainy, prickly or oily were also identified. Tannin activity was shown to be highly positively correlated to dry on the palate, and tannin concentration with both overall dry and dry on the palate. A significant partial least squares regression model showed that tannin concentration and activity (positive contribution) as well as pH values (negative) were good predictors of the mouthfeel dimension mainly related to dry and sticky terms.

Effects of distribution of sugars and organic acids on the taste of strawberries

The concentrations of sugars and organic acids as well as the total soluble solid (TSS) in different parts of the strawberry fruit were characterized. The data were used to create simulated fruit juice jellies, in order to clarify how the sugar and organic acid levels affect the taste. Such an approach eliminates the influence of external factors such as size, color, and texture when using real fruits in sensory evaluations. Further, the use of a jelly allowed us to simulate the concentration differences between various parts of the fruit. In the strawberry fruit, the sugar content is higher in the apex than in the peduncle; however, the level of organic acids is the same throughout. It was revealed that the sweetness and sourness in the apex and peduncle could be sufficiently recognized by humans as tastes. Also, a layered jelly sample replicating the sugar and acid distribution in real strawberry was perceived as less sweet and more sour, compared to a homogeneous one with the same overall composition. The likely reason is that the sourness in the peduncle is accentuated by the low TSS level, which decreases the TSS/total organic acid ratio that affects the sweetness/sour perceptions. Based on these results, factors for the appropriate sensory evaluation of fresh fruits in general were considered. Specifically, the distribution of sugars and organic acids in the fruit should be analyzed first, and bite-sized parts with concentrations close to the average provide the most accurate evaluation results.

Assessment Wine Aroma Persistence by Using an in Vivo PTR-ToF-MS Approach and Its Relationship with Salivary Parameters

To better understand wine aroma persistence, the nasal cavity of nine volunteers was monitored by Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) after they rinsed their mouths with three rosé wines (one control and the same wine supplemented with two tannin extracts) during four minutes. Wines were aromatised with a mixture of five target aroma compounds. Results showed that wine aroma persistence was highly compound-dependent: while esters disappeared very fast, other compounds such as linalool remained in the oral cavity for longer times after wine expectoration. A low effect of tannins (at 50 mg/L) on nasal cavity parameters was observed, with the exception for the compound ethyl decanoate that was significantly higher released in the presence of tannins. Strong interindividual differences on aroma persistence were also found. Significant positive correlations with the salivary total protein content and negative with the salivary flow were observed for specific compounds. This work has studied for the first time in vivo wine aroma persistence in real time from an analytical perspective.