Aroma Composition Research Articles

Multiomics correlation analysis on the mechanism of flavor substance formation during the processing of "Huanong 53″ black tea

A comprehensive investigation was conducted using targeted metabolomics, transcriptomics, and GC-MS techniques to study the dynamic changes in volatile and non-volatile metabolites, as well as gene transcription levels, in five processing stages of 'Huanong 53′ black tea (Camellia sinensis). A total of 2062 metabolites were identified, with flavonoids (428) and amino acids and their derivatives (194) being the main categories. The types and contents of flavor characteristic components of black tea changed most significantly during the withering and fermentation stages. Key elements of tea aroma composition, including linalool, benzeneacetaldehyde, and geraniol were found to correspond significantly with specific transcripts annotated as linalool synthase, aromatic aminotransferase, and geraniol diphosphate synthase, respectively. Throughout processing, a decrease in catechins and concomitant increase in oxidized catechin dimers, such as theaflavin (TF), was positively correlated with down-regulated flavonoid pathway gene expression and up-regulated expression of putative TF biosynthetic genes, including laccases, polyphenol oxidase, and a wide range of peroxidases. This study provides a comprehensive perspective on the changes in metabolites during black tea processing, and contributes to the research on improving black tea quality and the suitability of tea varieties for processing.

Four new wines from La Mancha region: Chemical characterization of oenological parameters, phenolic composition and volatile compounds

In this study, Carnelian, Barbera, Negro Amaro, and Limberger wines were obtained across two harvests from foreign red grape varieties cultivated in the La Mancha region. The results show that the general composition of all wines was in concordance with quality red wines from La Mancha region. The spectrophotometric method was employed to determine the main families of phenolic compounds and higher concentrations of these compounds were found in Carnelian wines. Free aroma compounds were isolated using solid-phase extraction (SPE), followed by analysis through gas chromatography-mass spectrometry (GC/MS). The GC-MS analysis of the wines identified 71 volatile compounds in Barbera wines and 58 free aroma compounds in Carnelian, Negro Amaro, and Limberger wines. The volatile compounds with the greatest capacity to introduce modifications in the aroma composition of the studied wines were (Z)-3-hexen-1-ol, 2-phenylethyl acetate, linalool, β-damascenone, phenylethyl alcohol, and butyric acid. This research presents the first comprehensive aromatic characterization of Carnelian, Barbera, Negro Amaro, and Limberger wines from the La Mancha region. The data suggested that these wines have great aromatic potential and can be considered viable alternatives to traditional grape varieties.

Integrating aromatic plants into indoor biophilic environments: Species selection based on psychophysiological effects and bioactive volatile compounds

To explore aromatic plants suitable for indoor biophilic environments and their impact on long-term indoor residents' psychophysiological health, a combined method using subjective ratings, objective electrophysiological signals, and aroma characteristics was employed. The study assessed 12 indoor plants' aromas and analyzed aroma components and their potential to intervene in psychophysiological health. Results showed that different plants had varying effects on psychophysiological health, some (e.g., Vicks Plant, rosemary) showed positive impacts across most measures, while others (e.g., basil, catnip) showed negative impacts. The aroma of false incense showed significant gender differences in its effects. Smelling Vicks Plants for 5 min significantly reduced heart rate (HR), increased heart rate variability (HRV), and enhanced vigor, positively correlated with volatile organic compounds (VOCs) and terpenes like linalool and limonene. Higher VOCs emission was associated with lower HR and reduced anger. Cluster analysis grouped Vicks Plant and rosemary based on aroma composition and effects on psychophysiological responses, providing a basis and framework for subsequent exploration of aromatic plants with psychophysiological regulation capabilities in indoor biophilic environments.

Dynamic Changes in Yeast Populations and Aroma Composition of ‘Beimei’ (Vitis vinifera × Vitis amurensis) during Spontaneous Fermentation

‘Beimei’ is a hybrid cultivar of Vitis vinifera and wild Vitis amurensis with fungus- and cold-resistant characteristics that is widely grown in many regions of China. However, studies on the yeast diversity and aroma compound composition of this cultivar remain scarce. Here, indigenous yeast diversity, aroma compound composition, and their dynamic changes during the spontaneous fermentation of ‘Beimei’ were investigated and monitored using high-throughput sequencing and gas chromatography-mass spectrometry. The result indicated that non-Saccharomyces yeasts were predominant at the initial stages of ‘Beimei’ spontaneous fermentation and then sharply decreased. Cladosporium herbarum and Hanseniaspora uvarum were identified as the dominant species of filamentous fungi and yeast, respectively, at the beginning and on the first day of fermentation, whereas unclassified_f_Saccharomycetacease was dominant throughout fermentation, starting from the third day until the end of fermentation. The main volatile aroma chemicals were esters and alcohols, which accumulated abundantly at the late stage of fermentation. Taken together, this study represents the first step in exploring untapped yeast species and aroma compounds, which is helpful for the screening of native yeasts from ‘Beimei’ and producing distinctive aroma wines.

Multi-omics profiling the dynamic variations of flavor and nutritional components during pearl gentian grouper soup processing

Flavor and nutritional value are essential components of fish soup, as highlighted by both producers and consumers. This study systematically examined the color, aroma, taste, and nutritional composition of pearl gentian grouper soup (PGGS) samples processed over varying durations, employing multi-omics technologies, including sensomics, volatilomics, lipidomics, and metabolomics. A comprehensive identification of 58 volatile aroma compounds, 407 lipids, 203 metabolites, and 47 taste components was achieved. The findings indicated that as processing time increased, the brightness of PGGS diminished, resulting in a thicker consistency. The aroma profile of PGGS was predominantly characterized by meaty and fatty notes, which were closely associated with carbonyl compounds (nonanal, dodecanal, (E)-2-octenal, and 2-undecanone) that developed due to glyceride oxidation during prolonged thermal processing. The predominant taste profile of PGGS was identified as umami, likely resulting from the synergistic effects of umami-enhancing amino acids (glutamic acid, aspartic acid) and 5ʹ-nucleotides (adenosine monophosphate, inosine monophosphate, guanosine monophosphate). Furthermore, PGGS may represent a significant source of taurine, with its taurine content accounting for over 60% of the total free amino acids (FAAs). Considering the variations in color, flavor, and nutritional content throughout the processing of PGGS, as well as the associated time costs, a processing duration of 2 h was optimal.

Unlocking the potential of Kluyveromyces marxianus in the definition of aroma composition of cheeses.

The cheese microbiota is very complex and is made up of technologically-relevant, spoilage, opportunistic and pathogenic microorganisms. Among them lactic acid bacteria and yeasts are the main ones. One of the most interesting dairy yeasts is Kluyveromyces marxianus because of its technological properties including the ability to produce aroma compounds. This study investigated the contribution of Kluyveromyces marxianus to the gross composition and aroma profile of cow cheeses. Experimental cheeses were prepared by inoculating a co-culture of K. marxianus FM09 and a commercial strain of Lacticaseibacillus casei and compared with cheeses obtained with only L. casei. The gross composition was determined by a FoodScan™ 2 Dairy Analyser, and free amino acids were evaluated at 507 nm after reaction with Cd-ninhydrin. The volatile organic compounds were extracted by head-space solid phase micro-extraction and analyzed by gas chromatography-mass spectrometry coupled with odor activity values. qRT-PCR was applied to determine the expression of genes involved in esters synthesis and degradation. The inoculation of K. marxianus induced an increase of pH and a reduction of protein content of cheeses, in agreement with the stronger proteolysis detected in these cheeses. K. marxianus influenced the content of aroma compounds both quantitatively and qualitatively. In particular, an increase of higher alcohols, esters and organic acids was observed. Moreover, 12 compounds were detected only in cheeses obtained with the co-culture. These differences were in agreement with the odor activity values (OAV). In fact, only 11 compounds showed OAV > 1 in cheeses obtained with the commercial strain, and 24 in those obtained with the co-culture. The qPCR analysis revealed an over expression of ATF1, EAT1, and IAH1 genes. Kluyveromyces marxianus could act as an important auxiliary starter for cheese production through the development and diversification of compounds related to flavor in short-aged cow cheeses.

Transcriptomic profiling of the floral fragrance biosynthesis of Iris germanica ‘Harvest of Memories’ and functional characterization of the IgTPS14 gene

Iris (Iris germanica) is a very popular ornamental plant and is known for the precious spice irone produced from its roots. Many iris varieties can also release fragrances through their flowers. However, the composition of iris aroma and the molecular mechanism of its synthesis have not been reported. In this study, we analyzed the volatile floral compounds of I. germanica ‘Harvest of Memories’ at different stages and in different tissues through headspace solid-phase microextraction gas chromatography-mass spectrometry. A total of 36 volatile compounds were identified, and linalool was the dominant component. Transcriptome analysis showed that 35 differentially expressed genes and 218 differentially expressed transcription factors were positively correlated with linalool release. According to the results of qRT-qPCR, the expression level of the IgTPS14 gene was consistent with the release trend of linalool, suggesting that IgTPS14 may play a certain role in linalool synthesis. Phylogenetic analysis showed that the IgTPS14 protein belonged to the TPS-g subfamily. An in vitro enzymatic assay of IgTPS14 and its transient and stable overexpression in tobacco indicated that this gene produced linalool. The transient silencing of IgTPS14 in petals by virus-induced gene silencing technology revealed a significant reduction in the release of linalool. These results will help explore and reveal the molecular mechanism of monoterpenoid synthesis and provide a certain reference for studying the formation of iris aroma.

Molecular Aroma Composition of Vanilla Beans from Different Origins.

The demand for natural Vanilla has increased rapidly, creating the need for more potential sources of high-quality Vanilla essence. Understanding the geographical influences on the aroma profile of Vanilla is essential. This study demonstrates the first comparative analysis of odorant compositions in the three most important Vanilla varieties: Vanilla planifolia, Vanilla pompona, and Vanilla tahitensis from different origins. Following the screening for odor-active molecules through gas chromatography-olfactometry and aroma extract dilution analysis (GC-O and AEDA), selected compounds were quantified using stable isotope dilution assays (SIDA) and their dose over threshold values (DoTs) were calculated. Vanillin was confirmed as the most important odor-active compound due to its highest DoT value, especially in the V. planifolia sample. Meanwhile, 4-methoxybenzyl alcohol and 4-methoxybenzaldehyde showed higher DoT factors than vanillin in V. pompona and partially in V. tahitensis samples. This indicates their role as discriminative odorants for these varieties. The heightened DoT values of 3-hydroxy-4,5-dimethyl-2(5H)-furanone in Uganda Vanilla samples unveil geographical influences on the odorant profile within V. planifolia species. Additionally, 2-methyl-3-(methyldithio)furan was identified for the first time in Vanilla samples with diverse DoT values from different species and origins.

Variation in the Aroma Composition of Jasmine Tea with Storage Duration.

This study investigated the changes in the aroma of jasmine tea during storage. Solid-phase micro-extraction (SPME)-gas chromatography (GC)-mass spectrometry (MS) and stir bar sorptive extraction (SBSE)-GC-MS were combined to detect all volatile compounds. GC-olfactometry (GC-O), odor activity value (OAV), and p-value were employed to analyze and identify the key aroma compounds in six jasmine tea samples stored for different durations. Nine key aroma compounds were discovered, namely (Z)-3-hexen-1-yl acetate, methyl anthranilate, methyl salicylate, trans-β-ionone, linalool, geraniol, (Z)-4-heptenal, benzoic acid methyl ester, and benzoic acid ethyl ester. The importance of these compounds was confirmed through the aroma addition experiment. Correlation analysis showed that (Z)-4-heptenal might be the main reason for the increase in the stale aroma of jasmine tea. Through sensory evaluation and specific experimental analysis, it can be concluded that jasmine tea had the best aroma after 3 years of storage, and too long a storage time may cause the overall aroma of the tea to weaken and produce an undesirable odor. The findings can provide a reference for the change in aroma during the storage of jasmine tea and provide the best storage time (3 years) in terms of jasmine tea aroma.

The relevant and complex role of ethanol in the sensory properties of model wines

In a context of increasing interest in the production of wine-based beverages with lower ethanol content, the present work explored the role of ethanol in the sensory properties of model wines (MW). Four sets of MWs (red and white) with alcohol contents ranging from 0.5 to 15 % (1st study) and from 12 to 15 % (2nd study), the non-volatile fraction of real wines and fixed aroma compositions were all prepared and characterised by sensory descriptive analysis. The results indicate that sensory effects were stronger in red MWs than in white MWs, and that alcohol levels below 10 % in reds and 7.5 % in whites cause the models to become unbalanced with excessive sourness. In whites, low-alcohol MWs also showed reduced levels of perceived bitterness, and only at high ethanol levels were body and alcoholic aroma more intense. In reds, the low alcohol MWs showed less positive aroma persistence (perceived retronasally) and less body; at 0.5 % ethanol the positive odour intensity (perceived orthonasally) was minimal and at higher ethanol levels, the models became sweeter and more alcoholic. Overall, although samples with similar alcoholic contents maintained some sensory similarity, there were relevant discontinuities caused a slight increase in ethanol (0,5 %) to have a dramatic sensory impact, with some sensory descriptors showing significant maxima or minima at these alcohol levels. In reds, sourness, alcohol and astringency perceptions were maximum at 13.5 % and 15 % and body at 13 % and 15 %; meanwhile, red fruit was minimum at 13 % and 15 %, peaking at 14.5 %. In whites, alcohol perception was also maximum at 13.5 % and 15 %, while sweetness was maximum at 13.5 % and 14.5 %. These results demonstrate that ethanol exerts profound effects on sensory properties, probably due to strong perceptual interactions with odour, taste and tactile properties.

Physical and Chemical Changes of Seven Selected Herbs Used as Herbal Bath Affected by Different Drying Methods

The effect of oven drying (OD) at 50±5°C, sun drying (SD), and fresh leaves (control) of seven selected herbs used in herbal preparation as herbal baths were evaluated. Herbal baths (HB) involve mixing herbs into water and boiling them or simply immersing them in the mixture during a regular bath. The herbs selected were leaves of torch ginger, greater galangal, pandan, citronella grass, henna, betel leaves, and kaffir lime leaves and fruits. The herbs were planted in a plot at the Institute of Bioscience, Universiti Putra Malaysia, Malaysia. Physical changes such as HB herbs’ colour, aroma, and chemical composition were evaluated. The hydro distillation method was used for the extraction process of HB herbs, where it produced essential oils (EO), essential water (EW), and boiling water (BW), and their chemical composition was determined by gas chromatography-mass spectrometry. As a result, the OD herbs possessed brighter and more attractive colours compared to the SD method, which was dull and pale. The colour of EO was yellow, colourless for EW, and reddish for BW. Additionally, OD herbs possessed 80% and only 50% of the scent strength of the SD herbs from extracting fresh herbs. The fresh and dried HB herbs contained chemical constituents mostly from the terpene group. Herbal preparation developed using all treatments retained an appreciable amount of chemical composition studied, thus having the potential for commercial purposes.

Influence of Cheese Composition on Aroma Content, Release, and Perception.

The quality of a cheese is determined by the balance of aroma compounds primarily produced by microorganisms during the transformation of milk into ripened cheese. The microorganisms, along with the technological parameters used in cheese production, influence aroma formation. The perception of these compounds is further influenced by the composition and structure of the cheese. This study aimed to characterize how cheese composition affects aroma compound production, release, and perception. Sixteen cheeses were produced under controlled conditions, followed by a quantitative descriptive analysis post ripening. Aroma composition was analyzed using HS-SPME-GC-MS, and a dynamic sensory evaluation (TCATA) was combined with nosespace analysis using PTR-ToF-MS. Image analysis was also conducted to characterize cheese structure. Cheese fat and whey lactose contents were identified as key factors in the variability of sensory attributes. GC-MS analyses identified 27 compounds correlated with sensory attributes. In terms of aroma compound release, 23 ions were monitored, with fat, salt, and lactose levels significantly affecting the release of most compounds. Therefore, cheese fat, salt, and whey lactose levels, as well as the types of microbial strains, play a role in influencing the composition, structure, release of aroma compounds, and sensory perception.

Characterization of key aroma compounds in a novel Chinese rice wine Xijiao Huojiu during its biological-ageing-like process by untargeted metabolomics

Xijiao Huojiu (Xijiao), an ancient Chinese rice wine (ACRW), is produced using traditional methods, which involve biological-ageing-like process and result in distinctive sensory profiles. However, its aroma composition is still unclear. In this study, the aroma characteristics of three samples with varying ageing times were examined. Xijiao_SCT, with a short cellar time, exhibited a strong fruity and floral aroma and a less grain-like aroma. Conversely, Xijiao_LCT, which had a long cellar time, had a deep cocoa- and caramel-like aroma. A total of 27 key odorants that greatly influenced the aroma characteristics of Xijiao were identified. Comparative studies were used to identify 12 key odorants that distinguish Xijiao from modern Chinese rice wine (MCRW) and grape wines (GW). Additionally, 13 dominant latent ageing markers differentiated Xijiao_SCT from Xijiao_LCT. Our results suggested that ACRW and MCRW have overlapping but distinct volatile metabolomic profiles, highlighting the characteristics of ACRW during ageing process.

Investigations on whole cell biocatalysts with application in beverage production and aroma composition

Investigations on whole cell biocatalysts with application in beverage production and aroma composition

Effects of different fixation methods on the aroma quality of Anjibai tea

Fixation is a crucial step in the processing of Anjibai tea. In this study, gas chromatography tandem with mass spectrometry was used to analyze the aroma compositions of Anjibai tea across three types of fixation methods: roller-electrical fixation (REF), carding machine fixation (CMF), and roller-hot air fixation (RHF). Nine key volatile compounds were found responsible for Anjibai tea's aroma variations. Results from quantitative descriptive analyses, along with aroma recombination and omission tests, showed that linalool and geraniol significantly contribute to the formation of the medium flowery, fruity, and honey aromas in the REF samples; hexanal has a significant impact on the green aroma in the CMF samples; and 2-ethyl-3,6-dimethylpyrazine is an important aroma compound for the strong roasty aroma in the RHF samples. These findings provide an important theoretical foundation for improving the aroma quality of Anjibai tea and selecting the optimal fixation method.

Kimchi Lactic Acid Bacteria Starter Culture: Impact on Fermented Malt Beverage Volatile Profile, Sensory Analysis, and Physicochemical Traits.

Starter cultures used during the fermentation of malt wort can increase the sensory characteristics of the resulting beverages. This study aimed to explore the aroma composition and flavor recognition of malt wort beverages fermented with lactic acid bacteria (Levilactobacillus brevis WiKim0194) isolated from kimchi, using metabolomic profiling and electronic tongue and nose technologies. Four sugars and five organic acids were detected using high-performance liquid chromatography, with maltose and lactic acid present in the highest amounts. Additionally, e-tongue measurements showed a significant increase in the sourness (AHS), sweetness (ANS), and umami (NMS) sensors, whereas bitterness (SCS) significantly decreased. Furthermore, 20 key aroma compounds were identified using gas chromatography-mass spectrometry and 15 key aroma flavors were detected using an electronic nose. Vanillin, citronellol, and β-damascenone exhibited significant differences in the flavor profile of the beverage fermented by WiKim0194, which correlated with floral, fruity, and sweet notes. Therefore, we suggest that an appropriate starter culture can improve sensory characteristics and predict flavor development in malt wort beverages.

Differences in organic Pinot Noir wine production systems correlated with microbiome analysis, sensory characteristics and volatile composition

The action of microorganisms on grape must during the fermentation process contributes significantly to the organoleptic properties of wine. The influence of the environment on microbial growth and metabolism is also well recognized. Organic winemakers rely on indigenous yeasts to drive their fermentation processes, however there are few studies that examine the possible influence of environmental factors on fermentation, and on sensory attributes of the finished product. We previously used a community metabarcoding approach to analyse the microbiome associated with organic wine produced in two differing environmental systems; outdoors (vineyard) and indoors (winery). The resultant wine from both systems were then assessed for aroma composition using GC-MS, and sensory attributes by a group of wine experts. Possible correlations between the identified microbial populations and sensory attributes were investigated to determine potential drivers. The results confirm the crucial role of the yeast, Saccharomyces in the modification of wine aroma and flavour. Moreover, analysis of the output of differential gene expression analysis (DESeq2) showed that the genus Gluconobacter might influence the ‘Mouth feel’ (astringency/tannin) and taste (bitterness) attributes of wines. Some volatile compounds were uniquely associated with a single wine. This suggests that measured differences in microbial community composition might play roles in their synthesis. Collectively, these results contribute to understanding the interplay of the complex microbial community matrix present in ‘wild’ ferments in terms of sensory and chemical characteristics of wine.

Comparison of the Chemical and Aroma Composition of Low-Alcohol Beers Produced by Saccharomyces cerevisiae var. chevalieri and Different Mashing Profiles

Comparison of the Chemical and Aroma Composition of Low-Alcohol Beers Produced by Saccharomyces cerevisiae var. chevalieri and Different Mashing Profiles

Volatile Profile Characterization of Jujube Fruit via HS-SPME-GC/MS and Sensory Evaluation.

Current research does not fully elucidate the key compounds and their mechanisms that define the aroma profile of fresh jujube fruits. Therefore, this study conducted a comprehensive analysis of both free and glycosidically bound aroma compounds in fresh jujube fruits of ten cultivars. Utilizing gas chromatography-mass spectrometry (GC-MS), we identified 76 volatile free aroma compounds and 19 glycosidically bound volatile compounds, with esters, aldehydes, and ketones emerging as the predominant volatile compounds in the jujube fruits. Odor activity value (OAV) analysis revealed that the primary aroma profile of the jujubes is characterized by fruity and fatty odors, with β-damascenone being a key contributor to the fruity aroma, and (E)-2-oct-en-1-al and nonanal significantly influencing the fatty aroma. Moreover, the integration of sensory evaluation and partial least squares regression (PLSR) analysis pinpointed octanal, (E)-2-oct-en-1-al, nonanal, β-damascenone, and pentanal as significant contributors to the jujube's characteristic aroma, while isoamyl acetate was identified as significantly influencing the fatty acid taste. This study not only underscores the complexity of the jujube aroma composition but also highlights the impact of environmental factors on aroma profiles, offering valuable insights into the sensory characteristics of jujube fruits.

Characterization of key aroma-active compounds in fresh and vacuum freeze-drying mulberry by molecular sensory science methods

Mulberry is prone to rapid deterioration, but its quality can be maintained through vacuum freeze-drying. In this study, the aroma compositions of fresh mulberry (FM) and vacuum freeze-dried mulberry (VFDM) were analyzed through headspace solid-phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) coupled with GC×GC–O–TOF-MS. A total of 232 volatiles were detected in FM and VFDM, and the content of volatile compounds in VFDM decreased by at least 21.37 % after drying compared to FM. Additionally, 51 and 50 aroma-active compounds were detected in FM and VFDM, respectively, with 13 aroma-active compounds being identified in FM initially. Based on the aroma extraction dilution analysis (AEDA) results, 14 compounds with high flavor dilution (FD) factors were accurately quantified by GC–MS. The calculated odor activity value (OAV) showed that a total of 12 compounds significantly contributed to the aroma of mulberry. Finally, aroma recombination and omission experimental results showed that (E,Z)-2,6-nonadienal, β-ionone, hexanal, and (E)-2-nonenal were the key aroma-active compounds in FM, whereas (E,Z)-2,6-nonadienal, β-ionone, (E)-2-nonenal, eugenol and ethyl isovalerate were the key aroma-active compounds in VFDM.