Aroma Extract Dilution Analysis Research Articles

Characterization of Key Odor-Active Compounds in Draft Beers for the Chinese Market Using Molecular Sensory Science Approaches

Beer is a popular alcoholic beverage worldwide. However, limited research has been conducted on identifying key odor-active components in lager-type draft beers for the Chinese market. Therefore, this study aims to elucidate the odor characteristics of the four most popular draft beer brands through a sensory evaluation and an electronic nose. Subsequently, the four draft beers were analyzed through solid-phase microextraction and liquid–liquid extraction using a two-dimensional comprehensive gas chromatography–olfactometry–mass spectrometry analysis (GC×GC–O–MS). Fifty-five volatile odor compounds were detected through GC×GC–O–MS. Through an Aroma Extract Dilution Analysis, 22 key odor-active compounds with flavor dilution factors ≥ 16 were identified, with 11 compounds having odor activity values > one. An electronic nose analysis revealed significant disparities in the odor characteristics of the four samples, enabling their distinct identification. These findings help us to better understand the flavor characteristics of draft beer and the stylistic differences between different brands of products and provide a theoretical basis for objectively evaluating the quality differences between different brands of draft beer.

Influence of Milk Pasteurization on the Key Aroma Compounds in a 30 Weeks Ripened Pilot-Scale Gouda Cheese Elucidated by the Sensomics Approach.

Gouda cheese was produced from pasteurized milk and ripened for 30 weeks (PM-G). By application of gas chromatography/olfactometry and an aroma extract dilution analysis on the volatiles isolated by extraction/SAFE distillation, 25 odor-active compounds in the flavor dilution (FD) factor range from 16 to 4096 were identified. Butanoic acid, 2- and 3-methylbutanoic acid, and acetic acid showed the highest FD factors, and 2-phenylethanol, δ-decalactone, and δ-dodecalactone were most odor-active in the neutral-basic fraction. Quantitations by stable isotope dilution assays followed by a calculation of odor activity values (OAVs) revealed acetic acid, 3-methylbutanoic acid, butanoic acid, and butane-2,3-dione with the highest OAVs. Finally, an aroma recombinate prepared based on the quantitative data well agreed with the aroma profile of the PM-G. In Gouda cheese produced from raw (nonpasteurized) milk (RM-G), qualitatively the same set of odor-active compounds was identified. However, higher OAVs of butanoic acid, hexanoic acid, and their corresponding ethyl esters were found. On the other hand, in the PM-G, higher OAVs for 3-methylbutanoic acid, 3-methylbutanol, 3-methylbutanal, and butane-2,3-dione were determined. The different rankings of these key aroma compounds clearly reflect the aroma differences of the two Gouda-type cheeses. A higher activity of lipase in the RM-G and higher amounts of free l-leucine in PM-G on the other side were responsible for the differences in the concentrations of some key aroma compounds.

The shaking and standing processing improve the aroma quality of summer black tea

Black teas harvested during the summer season usually have the defect of low aroma intensity, resulting in unacceptability from consumers. The shaking and standing (SS) process is key to the production of oolong tea and is believed to significantly improve the aroma quality. However, the specific effects of the shaking process on the aroma quality of black tea have not been elucidated. SSBT has a higher aroma intensity than BT, especially floral and sweet odors. By Aroma Extract Dilution Analysis (AEDA), 27 volatiles with flavor dilution factor (FD) above 8 were selected, of which 20 had odor activity values (OAV) values above 1; among them, 9 floral and sweet volatiles with high OAV were linalool (485 for BT, 918 for SSBT), (E)-β-ionone (389, 699), geraniol (315, 493), β-myrcene (25, 62), (E)-2-hexenal (2, 7), phenylacetaldehyde (44, 75), (Z)-3-hexenyl hexanoate (19, 41), 1-hexanol (9, 26), and 2-phenylethanol (2,3). Aroma reconstitution of these 20 volatiles showed reliable results of floral, sweet, fruity, and roasted odors, further validating the aroma and intensity profiles of the key odorants. Overall, our results reveal that the metabolite mechanism of the SS process improves the aroma quality of black tea, providing a theoretical basis and guiding measures for the production of high-aroma black tea.

Characterization of odor-active compounds in Liuzhou River snail rice noodles soup by sensory-directed flavor analysis

Liuzhou River snails rice noodles, a special snack of Liuzhou City in the Guangxi Zhuang Autonomous Region, China, possess a unique flavor of spicy, refreshing, fresh, sour, and hot. The present study aimed to characterize the composition of volatile compounds and key odor-active compounds in river snails rice noodles soup (RSRNS) through aroma extract dilution analysis and odor activity value calculation using solid-phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC–O–MS) and gas chromatography–olfactometry–mass spectrometry (GC–O–MS). A total of 71 volatile compounds were identified by GC–O–MS, of which 49 were odor-active. Meanwhile, 125 volatile compounds were identified by GC×GC–O–MS, of which 68 were odor-active. These results indicated that 3-methylbutanal, linalool, 1,8-cineole, myrcene, 2-acetylpyrazine, 4-allylanisole, 2-acetylthiazole, 1-octen-3-ol, hexanal, and eugenol were the main odor-active compounds of RSRNS.

Characterization of important odorants from Persian silk tree flowers, Albizia julibrissin

AbstractThe Persian silk tree (Albizia julibrissin) has delicate flowers with a pleasant aroma profile, displaying notes of hyacinth and rose with subtle nuances of citrus, coconut and spice. In this study, a total of 29 odorants were identified in the flowers from a single A. julibrissin selection by the application of a cold‐solvent extraction (CSE), followed by solvent‐assisted flavour evaporation (SAFE) and aroma extract dilution analysis (AEDA). Subsequently, nine odorants with flavour dilution (FD) factors ≥16 were quantitated by stable isotope dilution analysis (SIDA), and odour activity values (OAVs) were calculated. Odorants with OAV ≥1 included 2‐phenylacetaldehyde (OAV 3638), linalool (OAV 797), eugenol (OAV 231), geraniol (OAV 161), 1H‐indole (OAV 93), β‐ionone (OAV 31), 2‐phenylethanol (OAV 11) and γ‐octalactone (OAV 1). An aroma simulation model was prepared based on the quantitation data, and it closely matched the aroma of the flower isolate. Chiral chromatography was performed, and (S)‐(+)‐linalool was the only enantiomer detected. This study advances our understanding of A. julibrissin flower aroma chemistry and lays the groundwork for future investigations for the development of delicate floral aromas for flavour and fragrance applications.

Characterization of Odorants in a Commercial Culinary Sage (Salvia officinalis L.) and Several Cultivars.

Culinary sage, Salvia officinalis L., is a popular spice plant commonly used throughout the world. In this study, 35 odorants were identified in dried sage via solvent-assisted flavor evaporation (SAFE) and aroma extract dilution analysis (AEDA), including 9 that were identified in sage for the first time. Fifteen odorants were quantitated by stable isotope dilution analysis (SIDA), and their odor activity values (OAVs) were determined. Odorants with high OAVs included (2E,6Z)-nona-2,6-dienal, 1,8-cineole, and β-myrcene. A formulated aroma simulation model closely matched the aroma profile of an aqueous infusion of dried sage. Enantiomeric proportions of selected odorants were determined by chiral gas chromatography. Furthermore, 6 different sage cultivars were grown in the greenhouse, dried under the same conditions, and analyzed. Sensory analysis determined that all cultivars were dominated by an herbaceous sensory attribute and had varying intensities of eucalyptus, mint, clove, pine, green, earthy, floral, and citrus notes. Cultivars with varying intensities of herbaceous, eucalyptus, pine, and green sensory notes correlated with the OAVs of α-thujone/β-thujone, 1,8-cineole, α-pinene, and (2E,6Z)-nona-2,6-dienal, respectively. This study identified the odorants driving the sensory profiles of different sage cultivars and serves as a foundation for future studies on the aroma chemistry of culinary sage.

Characterization of the key aroma compounds of wild bitter melon lujiu based on LLE coupled with GC–O–MS and the aroma influence of polysaccharide addition using VASE–GC–MS

Wild bitter melon (Momordica charantia L. Var. Abbreviata Ser; WBM) is widely cultivated in East and Southeast Asia. It is made into lujiu with high-quality strong-flavor baijiu and presents a beautiful golden color and harmonious aroma. Lujiu is a type of alcoholic beverage similar to gin. In this study, the aroma profile of wild bitter melon lujiu (WBML) was determined through sensory evaluation, and important aroma-active compounds were identified through liquid–liquid extraction (LLE) coupled with gas chromatography–olfactometry–mass spectrometry (GC–O–MS) and aroma extraction dilution analysis (AEDA). A total of 42 aroma-active compounds were identified, and 28 of them with FD factor ≥ 3 were quantified. Sixteen compounds were pivotal aroma contributors, among which ethyl hexanoate, ethyl pentanoate, ethyl butanoate, ethyl octanoate, and acetic acid had the highest OAVs. Moreover, WBM-sourced aroma compounds were found in WBML, including dihydroactinidiolide, (E,E)-2,4-nonadienal, β-ionone, etc. The extraction parameters of vacuum-assisted sorbent extraction (VASE) were optimized for the first time to analyze lujiu aroma. The effect of homologous polysaccharide addition to the aroma of WBML was explored with VASE–GC–MS. The greasy off-odor was decreased due to the reduction of ethyl octanoate volatility by polysaccharide addition.

Variations in Key Aroma Compounds and Aroma Profiles in Yellow and White Cultivars of Flammulina filiformis Based on Gas Chromatography-Mass Spectrometry-Olfactometry, Aroma Recombination, and Omission Experiments Coupled with Odor Threshold Concentrations.

Flammulina filiformis (F. filiformis) is called the 'benefiting intelligence' mushroom. There is a notable difference between a yellow cultivar (with a robust aroma) and a white mutant cultivar (with a high yield) of F. filiformis. A thorough analysis of aroma differences is essential to improve the aroma of high-yield strains. This study employed a combination of gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and aroma extract dilution analysis (AEDA) to analyze the variations in aroma compounds. Then, the contribution of the odorants was determined using flavor dilution (FD) factors and odor activity values (OAVs). Aroma omission and recombination experiments were used to identify the key odorants. A total of 16 key aroma compounds were characterized in F. filiformis, along with four eight-carbon volatiles (3-octanone, 3-octanol, octanal, and 1-octen-3-ol). Finally, the dominant aroma characteristic was "sweet" for the yellow strain, while it was "green" for the white strain. More research is required to investigate the enzymes and corresponding genes that regulate the synthesis of aroma compounds in F. filiformis for future breeding programs.

Characterization of key aroma compounds in soy sauce flavor baijiu by molecular sensory science combined with aroma active compounds reverse verification method

The distinctive flavor profile of soy sauce flavor baijiu (SAB) is shaped by its unique aroma compounds. The characteristic aroma compounds in Langjiu soy sauce flavor baijiu (LSAB) were explored based on molecular sensory science. A total of 66 aroma active compounds were identified by gas chromatography–olfactometry (GC–O) combined with aroma extract dilution analysis (AEDA), and 6 important unknown sulfur compounds were identified using the aroma active compounds reverse verification method (ACRVW). A total of 39 key aroma compounds were determined to have odor activity values (OAVs) ≥ 1. The aroma contribution of aroma components was verified by aroma recombination and aroma omission experiments. 15 characteristic aroma compounds were identified in LSAB. Meanwhile, a simple and easy-to-understand sensory expression language was described to fully understand the style characteristics of LSAB. Overall, the present paper offers insights into research uncovering the key “sauce flavor” of soy sauce flavor baijiu.

Comparative key aroma compounds and sensory correlations of aromatic coconut water varieties: Insights from GC × GC-O-TOF-MS, E-nose, and sensory analysis

Aroma is a key criterion in evaluating aromatic coconut water. A comparison regarding key aroma compounds and sensory correlations was made between Thailand Aromatic Green Dwarf (THD) and Cocos nucifera L. cv. Wenye No. 4 coconut water using E-nose and GC × GC-O-TOF-MS combined with chemometrics. Twenty-one volatile components of coconut water were identified by GC × GC-O-TOF-MS, and 5 key aroma compounds were analyzed by relative odor activity value and aroma extract dilution analysis. Moreover, the combination of the E-nose with orthogonal partial least squares was highly effective in discriminating between the two coconut water samples and screened the key sensors responsible for this differentiation. Additionally, the correlation between volatile compounds and sensory properties was established using partial least squares. The key aroma compounds of coconut water exhibited positive correlations with the corresponding sensory properties.

Molecular Background of the Lychee Aroma of Vitis vinifera L. 'Muscaris'.

Muscaris is a modern white grape variety with good fungal resistance and a pleasant aroma, the molecular background of which was unknown. A comparative aroma extract dilution analysis applied to Muscaris grapes and grapes of the father variety Muskateller revealed little differences and resulted in 39 and 35 odorants, respectively. Sixteen odorants exceeded their odor threshold concentrations. Odor reconstitution and omission experiments showed that the distinct lychee note in the aroma of the Muscaris grapes was generated by the combination of (2S,4R)-rose oxide and geraniol. This finding will guide further molecular research on the transfer of the lychee note into wine and may also be helpful for the targeted breeding of new grape varieties.

Characterization of light-induced aroma components in green tea beverages using aroma extract dilution analysis with gas chromatography–olfactometry

Characterization of light-induced aroma components in green tea beverages using aroma extract dilution analysis with gas chromatography–olfactometry

Effect of Dehulling Pretreatment on the Flavor of Sesame Paste.

Gas chromatography-olfactory-mass spectrometry (GC-O-MS) combined with Aroma Extract Dilution Analysis (AEDA) were employed to characterize the key odor-active compounds in sesame paste (SP) and dehulled sesame paste (DSP). The AEDA results revealed the presence of 32 and 22 odor-active compounds in SP and DSP, respectively. Furthermore, 13 aroma compounds with FD ≥ 2, OAV ≥ 1, and VIP ≥ 1 were identified as key differential aroma compounds between SP and DSP. Specifically, compounds such as 3-methylbutyraldehyde (OAV = 100.70-442.57; fruity), 2-methylbutyraldehyde (OAV = 106.89-170.31; almond), m-xylene (FD = 16; salty pastry), and 2,5-dimethylpyrazine (FD = 8-16; roasted, salty pastry) played an important role in this differentiation. Additionally, the dehulling process led to increased fermented, sweet, green, and nutty aroma notes in DSP compared to the more pronounced burnt and roasted sesame aroma notes in SP. Our findings offer a theoretical foundation for the regulation of sesame paste aroma profiles.

Peracetic acid residues in orange juice can lead to a 5-vinylguaiacol-induced clove-like off-flavor via Baeyer-Villiger oxidation of hesperidin

A balanced flavor is a major quality attribute of orange juice. Formation of 4-vinylguaiacol during storage can lead to an undesirable clove-like off-flavor. However, clove-like off-flavors were occasionally reported despite low 4-vinylguaiacol concentrations, suggesting an alternative molecular background. Application of gas chromatography–olfactometry and aroma extract dilution analysis to an orange juice with a pronounced clove-like off-flavor resulted in the identification of 5-vinylguaiacol. The compound showed the same odor as 4-vinylguaiacol, but was previously unknown in orange juice. In five of six commercial orange juices with clove-like off-flavors, 5-vinylguaiacol was even more odor-active than 4-vinylguaiacol. Spiking and model studies suggested that 5-vinylguaiacol is formed during pasteurization from the natural orange juice component hesperidin and residual peracetic acid used as cleaning agent by a Baeyer-Villiger oxidation. An activity-guided screening approach confirmed the role of hesperidin as 5-vinylguaiacol precursor. In conclusion, peracetic acid should no longer be used in orange juice processing plants.

The key aroma components of steamed green tea decoded by sensomics and their changes under different withering degree

Steamed green tea has a long history and unique aroma, but little is known about its key aroma components. In this study, 173 volatiles in steamed green tea were identified using solvent-assisted flavor evaporation and headspace-solid phase microextraction plus two chromatographic columns of different polarities. Aroma extract dilution analysis revealed 48 highly aroma-active compounds with flavor dilution factors 64–1024. Internal standards were used to calculate odorant active value (OAV), and 11 OAV > 1 key aroma compounds were determined. Omission test identified eight substances, including dimethyl sulfide, (E)-β-ionone, cis-jasmone, linalool, nonanal, heptanal, isovaleraldehyde and (Z)-3-hexenol, as the key aroma active compounds of steamed green tea. With the increase of withering degree, the content of these substances increased first and then decreased except for heptanal and cis-jasmone. Moreover, the water content of 62 % was suggested to be an appropriate withering degree during the processing of steamed green tea.

Sensomics-Assisted Characterization of Fungal-Flowery Aroma Components in Fermented Tea Using Eurotium cristatum.

Fermented tea (FT) using a single Eurotium cristatum strain can produce a pleasant fungal-flowery aroma, which is similar to the composite aroma characteristic of minty, flowery, and woody aromas, but its molecular basis is not yet clear. In this study, solvent-assisted flavor evaporation and gas chromatography-mass spectrometry/olfactometry were applied to isolate and identify volatiles from the FT by E. cristatum. The application of an aroma extract dilution analysis screened out 43 aroma-active compounds. Quantification revealed that there were 11 odorants with high odor threshold concentrations. Recombination and omission tests revealed that nonanal, methyl salicylate, decanoic acid, 4-methoxybenzaldehyde, α-terpineol, phenylacetaldehyde, and coumarin were the major odorants in the FT. Addition tests further verified that methyl salicylate, 4-methoxybenzaldehyde, and coumarin were the key odorants for fungal-flowery aroma, each corresponding to minty, woody, and flowery aromas, respectively. 4-Methoxybenzaldehyde and coumarin were newly found odorants for fungal-flowery aroma in FT, and 4-methoxybenzaldehyde had not been reported as a tea volatile compound before. This finding may guide future industrial production optimization of FT with improved flavor.

Characteristic aroma improvement mechanisms of heat-sterilized bayberry juice regulated by exogenous polyphenols.

Bayberry juice is favored for its unique taste and flavor, while heat sterilization tends to reduce the aroma quality during processing, which limits its acceptability to consumers. To address this issue, we use exogenous polyphenols to regulate flavor compounds to improve the product quality. Total 13 differential key aroma-active compounds were identified between fresh bayberry juice (FBJ) and heat-sterilized bayberry juice (HBJ) using aroma extract dilution analysis (AEDA), orthogonal partial least squares-discriminant analysis (OPLS-DA) and odor activity values (OAVs). Further, eight polyphenols were added to investigate their influences on the aroma quality of HBJ respectively. The results showed that all tested polyphenols could maintain the aroma profile of HBJ closer to FBJ and improve the odor preference of HBJ, among which resveratrol and daidzein were most effective. Their aroma molecular regulatory mechanism involved enhancing the characteristic aroma of bayberry and reducing the certain off-flavored compounds produced by heat sterilization.

L-Cysteine involved Maillard peptides of distillers’ grain hydrolysates: Browning, formation of characteristic flavor and improvement on fracturability of sugared garlic

Maillard peptides (MPs) were derived from distillers’ grain hydrolysates (DGPs) and fructose, and MPs prepared with and without exogenous l-cysteine were respectively defined as DFCs and DFs. The influences of extra-added l-cysteine was investigated on the browning, taste properties (salty, umami, and kokumi), and characteristic volatile compounds of MPs. Eleven aroma-active compounds were identified as the key volatile compounds of MPs through aroma extract dilution analysis (AEDA) and odor active values (OAVs). Partial least squares regression (PLSR) was used to investigate the relationship between the sensory properties and the concentrations of the volatile compounds in DFCs and DFs. 3-Methylbutanal, 5-methyl-2-thiophenecarboxaldehyde, dimethyl trisulfide, trimethylpyrazine, and 3-ethyl-2,5-dimethylpyrazine, which significantly contributed to the caramel and roast characteristics of MPs, were inhibited through the addition of l-cysteine and regulation of temperature below 120 °C. The DFCs prepared at 110 °C for 120 min exhibited desirable taste properties and suitable aroma to non-thermal processed foods. When 0.3% DFCs were added to the soaking solution of sugared garlic, the hardness and fracturability of sugared garlic were increased by 45.26% and 19.15%, respectively, which meant this MPs could be used to improve the edible texture of sugared garlics.

Contribution of Key Odorants from Skins, Seeds, and Stems to the Aroma of Chardonnay Marc: A Valuable Coproduct of the Wine Industry.

Chardonnay marc, a co-product of the wine making industry, has recently garnered attention due to its health-promoting properties and is growing in popularity as a potential healthy and flavorful food ingredient. While previous studies have characterized the odorants in marc skins and identified the key odorants in marc seeds, the key odorants in the skins and stems and the contribution of each component to the whole marc aroma remains unknown. In this study, 27 odorants were identified in marc stems using solvent-assisted flavor evaporation and aroma extract dilution analysis. Four odorants were quantitated employing stable isotope dilution assays, and odor activity values (OAVs) were calculated. An odor simulation model prepared using odorants with OAVs > 1 sensorially matched the aroma of the marc stems. Omission studies showed that 3-methylnonane-2,4-dione, ethyl octanoate, oct-1-en-3-one, (2E,4E)-deca-2,4-dienal, (2E,4E)-nona-2,4-dienal, β-ionone, linalool, hexanal, HDMF, and 3-(methylsulfonyl)propanal were the key odorants in marc skins, while hexanal and 3-methylnonane-2,4-dione were the key odorants in marc stems. Mass balance studies suggested that the skins were the main contributor to the hay, floral, and fruity attributes of the whole marc, the seeds contributed mostly to the fatty attribute, and the stems had a minor contribution.

Characterization of the differences in aroma-active compounds in strong-flavor Baijiu induced by bioaugmented Daqu using metabolomics and sensomics approaches.

Bioaugmenting Daqu is an effective strategy to improve the quality of Baijiu, but its effect on overall flavor profiles and aroma-active compounds is unknown. Here, 168 volatiles were determined from fresh strong-flavor Baijiu (SFB) and bioaugmented Daqu increased their diversity and altered the flavor characteristics. Among 49 odorants identified by aroma extraction dilution analysis, 29 aroma-active compounds had odor activity values ≥1, of which 18, 8, and 3 components exhibited the highest content in the SFB fermented by fortified-, space- and conventional-Daqu, respectively. The contribution of increasing ethyl hexanoate and decreasing ethyl lactate of fresh SFB by bioaugmented Daqu was confirmed, and their content changed from 4650 and 1890mg/L (conventional-SFB) to 6680 and 1760mg/L (fortified-SFB) and 6130 and 1710mg/L (space-SFB). Meanwhile, the discriminators among different samples were determined by multivariate statistical analysis. These findings are beneficial for the optimization and improvement of Baijiu aroma.