Gas Chromatography-olfactometry Research Articles

HS–SPME combined with GC–MS and GC–O for characterization of key aroma-active compounds in fruity and grassy peppers (Capsicum chinense Jacq.)

Pepper (Capsicum spp.) is highly popular due to its unique flavor. However, there was limited research on the primary volatiles that influence the different flavors of fresh peppers. In this study, peppers with three aroma compound types denoted as “grassy,” “fruity,” and “no special aroma” (control) were analyzed using sensory evaluation combined with gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O). Altogether, 393 volatiles were identified by GC–MS, and the main volatiles in peppers (C. chinense Jacq.) were esters and terpenoids. GC–O and relative odor activity value analysis revealed that 2-isobutyl-3-methoxypyrazine had a highly bitter, spicy aroma intensity in all peppers. Hexanal and trans-2-hexenal were the main aroma-active compounds in grassy peppers. In addition, citronellal was determined to be a crucial aroma-active compound in fruity peppers. This study offers a theoretical foundation for guiding the growth of the pepper processing industry and breeding.

Characterization of Odorants in Clustered Mountain Mint Pycnanthemum muticum.

The clustered mountain mint, Pycnanthemum muticum, is a pleasant-smelling, native North American plant. Despite its wide geographical presence across the United States and Canada, little is known about the specific odorants responsible for its pleasing aroma. Herein, 42 odorants were identified in the plant through solvent-assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC-O), and gas chromatography-mass spectrometry (GC-MS). Subsequent analysis involved determining flavor dilution (FD) factors using aroma extract dilution analysis (AEDA), quantitating 14 odorants through stable isotope dilution assays (SIDA), and calculating their odor activity values (OAVs). Several noteworthy odorants with OAV ≥ 1 included pulegone (mint, medicinal; OAV 276), 1-octen-3-one (mushroom; OAV 149), menthofuran (mint, petrol; OAV 139), nonanal (citrus; OAV 21), γ-nonalactone (coconut; OAV 13), 1,8-cineole (eucalyptus; OAV 12), mintlactone (mint, coconut; OAV 12), menthone (mint, fresh; OAV 7.3), α-pinene (pine; OAV 4), and piperitenone (mint; OAV 1.9). The study also determined the stereochemistry of various chiral odorants. An aroma simulation model was developed to validate the identification and quantitative results; upon evaluation using olfactory profile analysis, no significant differences were found between the aroma model and an aqueous infusion of P. muticum (P > 0.05). These findings lay the foundation for future investigations into the diversity of P. muticum selections and can provide valuable insights for studies on plant hybridization for food and flavor applications.

Qualitative and Quantitative Sex-Related Differences in the Perception of Single Molecules from Coffee Headspace.

One of the still-debated topics regarding the olfactory function concerns the presence or absence of sex-related differences in individuals. In this study, we checked for a relationship between the olfactory function of females and males and their ability to perceive single molecules, and researched how this can influence the intensity with which the complex odor formed by a set of single molecules is perceived. First, females and males were classified as normosmic or hyposmic based on the TDI olfactory score obtained using the Sniffin' Sticks test. Subsequently, the headspace of roasted coffee beans, as a complex olfactory stimulus, was broken down into single molecules by means of a chromatographic column; these were simultaneously conveyed to a mass spectrometer (for their subsequent classification) and to the human nose, which acts as a chemical sensor by means of an olfactometer port. The results obtained with this gas chromatography-olfactometry approach show both qualitative and quantitative differences between females and males, with females performing better than males. In addition, the odor intensity reported by females when sniffing pen #10, containing coffee aroma, is significantly higher than that reported by males. In conclusion, these data highlight that the human ability to perceive both single compounds and complex odors is strongly conditioned, not only by the olfactory function of individuals, but also by their sex.

Characterization of key aroma-active compounds in Zanthoxylum schinifolium by sensory evaluation and multiple instrumental analyses

The aroma characteristics of Zanthoxylum schinifolium from four different production areas in Sichuan were identified and compared. Aroma components were analyzed via sensory evaluation, gas chromatography–olfactometry–mass spectrometry (GC–O–MS), and comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (GC × GC–O–MS). The results revealed that minty, spicy, woody, fresh, citrus, and herbal notes could be perceived, with the Jinyang sample exhibiting the most significant aroma profile. Compared with GC–O–MS, GC × GC–O–MS offers advantages in identifying aroma-active compounds, and it can identify more types and quantities of aroma-active compounds. In this study, 40 aroma-active compounds from seven different classes were identified via GC × GC–O–MS. Through aroma extraction dilution analysis (AEDA), 14 aroma-active compounds were quantitatively analyzed, and odor activity values (OAVs) were calculated. Additionally, orthogonal partial least squares discriminant analysis (OPLS-DA) was employed to identify four aroma-active compounds with variable importance in projection (VIP) scores greater than 1, indicating their potential as identification markers. This study enhances our understanding of the sensory characteristics and aroma-active compounds of Zanthoxylum schinifolium.

Effect of Roasting Level on the Development of Key Aroma-Active Compounds in Coffee

Coffee roasting is considered the most critical process in the development of sensory characteristics. During this stage, a substantial number of compounds are generated. Nevertheless, only a limited number of these compounds are responsible for the aroma, referred to as key aroma-active compounds. This study aimed to assess the impact of roasting levels on the formation of these compounds. Coffee was roasted at four different levels: very light (RL85), light (RL75), medium (RL55), and extremely dark (RL25), according to the Specialty Coffee Association (SCA) guidelines. The extraction, olfactory evaluation, and identification of compounds were performed using solid-phase microextraction (SPME), gas chromatography–olfactometry (GC-O), and gas chromatography–mass spectrometry (GC-MS), respectively. A total of 74 compounds were successfully identified, of which 25 were classified as aroma-active compounds. RL75 and RL85 displayed similar aromatic profiles. RL55 was characterized by pleasant notes such as sweet, toasted hazelnut, and caramel. In contrast, RL25 was marked by undesirable odors including burnt notes, putrid, and sulfurous scents. This study is the first to identify key odorant compounds in coffee based on SCA roasting standards.

Aroma characterization of Sichuan and Cantonese sausages using electronic nose, gas chromatography–mass spectrometry, gas chromatography-olfactometry, odor activity values and metagenomic

The interest of Chinese consumers in meat-free sausages has increased considerably due to their health benefits, but the aroma quality is far from reaching the traditional fermented meat sausages. This study evaluated the aroma characterization of Sichuan and Cantonese sausages using electronic nose (E-nose), gas chromatography–mass spectrometry (GC–MS), gas chromatography-olfactometry (GC-O), odor activity values (OAVs) and metagenomic. Ninety-eight volatile compounds were identified. Among them, 23 odorants were perceived, and their intensity differed in the two groups of sausages. There was a significant difference in the volatile compound profile between Sichuan and Cantonese cooked sausages. E-nose sensors could differentiate them through specific responses to these volatile compounds. Furthermore, there was a significant difference in microbial communities between Sichuan and Cantonese sausages. For aroma quality improvement of meat-free sausages, studies should focus on controlling the formation of aroma compounds by aroma precursors and using different microorganisms to produce diverse meat aromas. Our results provide a reference for the implementation of these strategies.

Characterization of cooked cheese flavor: Volatile components.

The aim of this work was to identify volatiles that contribute to the aroma of cooked cheese, including the role of fat content in their development during cooking. Volatiles and odorants in cooked mature Cheddar were identified using a combination of SPME (solid-phase microextraction)/GC-O (gas chromatography-olfactometry) and SPME/GC-MS (gas chromatography-mass spectrometry). A selection of the odorants was quantitated in six cheeses, uncooked and cooked, (mature Cheddar, high-, medium-, and low-fat mild Cheddar, mozzarella, and Parmesan). Many compounds showed significant differences between cooked and uncooked cheese; Strecker aldehydes, pyrazines, and furanones were all significantly higher in cooked cheeses than in uncooked cheese, while ethyl esters (key odorants in uncooked cheese) were not detected in any of the cooked cheese. Principal component analysis demonstrated that fat concentration in mild Cheddar was positively correlated with the formation of potential odorants (the Strecker aldehydes, methanethiol, 2-methylketones, and fatty acids) upon cooking. Potential lipid precursors for these compounds are discussed. PRACTICAL APPLICATION: This research can be used by the dairy industry to develop better cheeses, especially low- and reduced-fat cheeses, for use in cooked applications such as toppings for pizzas and ready meals. Alternatively, this research describes key volatile compounds in cooked cheese that can be used by the flavoring industry to develop authentic cooked cheese flavorings.

Identification and formation of key aroma-active compounds in red jujube as affected by different processing methods

Processing methods significantly affect the aroma characteristics of red jujube; however, few studies have explored how. Gas chromatography–tandem mass spectrometric detection, gas chromatography–olfactometry, relative odor activity value and quantitative descriptive analysis were used to investigate the aroma changes of red jujube during typical processing (freeze drying, baking, frying and steaming); furthermore, the formation of aroma-active compounds in processed red jujube was predicted based on untargeted metabolomics. After freeze drying, the total aroma content increased by 0.90 %, while it decreased by 51.59 %, 74.11 % and 78.74 % after baking, frying and steaming, respectively. In addition, ethyl esters dominated the sweet and fruity notes in freeze-dried red jujube, which were formed via combination of fatty acids metabolism, pyruvate metabolism and amino acid catabolism. (E,E)-2,4-Decadienal derived from fatty acid oxidation dominated the fatty note in fried red jujube. 2-Ethyl-3,5-dimethylpyrazine formed via the Maillard reaction dominated the roasty notes of baked red jujube.

Impact of Different Wood Types on the Chemical Composition and Sensory Profile of Aged Tsipouro: A Comparative Study

The production of high-quality aged marc spirits includes a minimum period of six months of ageing in oak barrels. Lastly, producers are interested in alternative botanical origin wood. The present study is aimed at investigating the influence of Greek oak (Quercus trojana) and Greek chestnut (Castanea sativa) compared with French (Quercus petraia) and American oak (Quercus alba) on the chemical composition and sensorial characteristics of aged tsipouro, produced from marc from the Black Muscat variety. Gas chromatography–olfactometry–mass spectrometry (GC–O–MS) was used to identify volatile compounds of the aged tsipouro. Also, colour and polyphenol measurements were made, and an organoleptic evaluation was performed by 16 trained tasters. The findings revealed rather similar results between the tsipouro made from different wood species, especially between Greek and French oaks, and relative differentiation for that of chestnut. All the aged distillates exhibited a pleasant and rich aromatic potential, dominated by floral and fruity terpene varietal aromas as well as wood-related volatiles. Chestnut, with a high phenolic potential, gives pleasant organoleptic effects over time and can be an alternative wood for ageing spirits. This research highlights the importance of wood selection in the tsipouro ageing process and enables the use of Greek wood species in the ageing of spirits.

Comprehensive foodomics analysis reveals key lipids affect aroma generation in beef

Lipids are vital precursors to beef aroma compounds, but the exact lipid molecules influencing aroma generation remain unconfirmed. This study employs gas chromatography–olfactometry–mass spectrometry and absolute quantitative lipidomics to identify beef's aroma and lipid profiles and to examine lipid alterations post-thermal processing. The aim is to understand the role of lipids in aroma generation during beef's raw-to-cooked transition. Eighteen key aroma compounds were identified as significant contributors to the aroma of beef. 265 lipid molecules were quantified accurately, and we found that triglycerides containing C18:1 or C18:2 chains, such as TG(16:0_18:1_18:1), TG(16:0_18:1_18:2), TG(16:0_16:1_18:1), as well as phosphatidylcholine and phosphatidylethanolamine containing PC(16:1e_20:4), PC(16:0e_20:4), PC(18:2e_18:2), and PE(16:1e_20:4), played important roles in the generation of key aroma compounds in beef. C18:1, C18:2, C18:3, and C20:4 were key substrates for the formation of aroma compounds. In addition, lysophosphatidylcholine and lysophosphatidylethanolamine containing unsaturated fatty acid chains may serve as important aroma retainers.

Mechanism of the interaction between olfactory receptors and characteristic aroma compounds in sweet orange juice

The aroma compounds of three varieties of orange juice were extracted using solvent-assisted flavor evaporation (SAFE) and stir bar sorptive extraction (SBSE). A total of 41 aroma compounds were identified by gas chromatography-olfactometry (GC-O), among which 10 aroma compounds had an aroma intensity (AI) > 4.5. There were 53 aroma compounds identified by gas chromatography-mass spectrometry (GC-MS), 29 of which had an odor activity value (OAV) higher than 1. The findings indicated that (+)-limonene, linalool, hexanal, citral and myrcene were closely associated with the five characteristic aromas of orange juice. Furthermore, molecular docking was used to analyze the binding energies and interactions between these compounds and olfactory receptors (OR1A1, OR1D2, OR2W1, OR5AC2, OR1A2, and OR5M3). The average binding energies for these compounds at the six receptors were −6.2 kcal/mol, −6.0 kcal/mol, −5.8 kcal/mol, −5.1 kcal/mol, −6.3 kcal/mol and −4.7 kcal/mol, respectively. Hydrophobic interaction was a significant driving force in this process. Key residues such as Leu199 (OR1D2), Ala108 (OR1A2), Gly108 (OR2W1), Pro181 (OR5M3), Tyr261 (OR5AC2), and Val203 (OR1A1) played key roles in binding with characteristic aroma compounds. The formation mechanism of orange juice aroma was revealed, which provides theoretical guidance for the regulation of sweet orange aroma and flavor.

Effect of puffing treatment on volatile components of green tea explored by gas chromatography–mass spectrometry and gas chromatography-olfactometry

The effect of puffing treatment on the volatile components of green tea has been studied. A total of 155 volatile compounds were identified by using HS-SPME and SPE extraction methods, combined with gas chromatography–mass spectrometry (GC–MS). The total concentration of volatile compounds in puffed green tea increased by 2.25 times compared to that in before puffing. 12 key volatile compounds in green tea were identified before and after puffing using a combination of multivariate statistical analysis, GC-O, AEDA dilution analysis, and relative odor activity value (rOAV). The puffing process generates the Maillard reaction, where sugars react with amino acids to produce Maillard reaction products (such as pyrazine, pyrrole, furan, and their derivatives), giving them a unique baking aroma. The proportion of these compounds in the total volatile matter increased. The research results provided guidance and a theoretical basis for improving the aroma processing of green tea.

Unveiling the aromatic secrets: analysis of odor-active components in Cupressus torulosa needles essential oil using GC-O and aroma extract dilution analysis

ABSTRACT The essential oils derived from various coniferous species, including Cupressus torulosa, have been historically valued for their aromatic properties. In the present study, essential oil from C. torulosa needles (CTEO) was analyzed using Gas Chromatography (GC), Gas Chromatography-Mass Spectrometry (GC-MS), and Gas Chromatography-Olfactometry (GC-O) with Aroma Extract Dilution Analysis (AEDA). A total of 36 compounds were identified, with δ-3-carene (0.1824 ± 0.0084 mg/g), sabinene (0.1125 ± 0.036 mg/g), and terpinen-4-ol (0.0891 ± 0.0034 mg/g) as major constituents. Of these, 24 were odor-active. The aroma profile of CTEO featured top notes of green, fresh leafy, cool, fruity, and citrus scents, middle notes of dry woody tones, and base notes of spicy and dry characteristics. Predictive models including FD factor, Odor Activity Values, and Relative Flavor Activity highlighted α-pinene, α-terpinene, linalool, bornyl acetate, β-pinene, camphor, limonene, and terpinen-4-ol as key aroma contributors. This study provides valuable insights into the aromatic profile of CTEO, with potential applications in the aroma industry.

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.

Identification of volatile and odor-active compounds in Maojian herbal tea (Dracocephalum rupestre Hance)

Maojian herbal tea originates from Xinzhou, Shanxi, China, and is renowned as one of the prominent northern Chinese herbal teas. However, the volatile and key odor-active compounds in Maojian herbal tea have not been reported. Using headspace-solid-phase microextraction coupled with gas chromatography–mass spectrometry, a total of 87 volatile compounds were identified. Thirteen aroma compounds were distinguished as the key odor-active compounds of Maojian herbal tea based on gas chromatography–olfactometry analysis, and odor activity values, including trans-β-ionone, cis-jasmone, β-caryophyllene, humulene, hexanal, nonanal, linalool, alloocimene B, β-cyclocitral, β-bourbonene, ylangene, δ-cadinene and indole. The results of partial least squares regression analysis demonstrate strong correlations between the odor-active compounds and odor properties. β-Caryophyllene is the main contributor to the woody aroma of Maojian herbal tea. The results of the present study offer a scientific insight into the aroma profile of Maojian herbal tea.

Characterization of the Key Aroma Compounds of Soybean Flavor in Fermented Soybeans with Bacillus subtilis BJ3-2 by Gene Knockout, Gas Chromatography–Olfactometry–Mass Spectrometry, and Aroma Addition Experiments

Characterization of the Key Aroma Compounds of Soybean Flavor in Fermented Soybeans with Bacillus subtilis BJ3-2 by Gene Knockout, Gas Chromatography–Olfactometry–Mass Spectrometry, and Aroma Addition Experiments

Characterisation of aroma‐active compounds in wheat flour by molecular sensory science

SummaryFour different extraction methods were used to extract aroma compounds from flour. It was found that dynamic headspace sampling (DHS) was a better method for extracting aroma‐active compounds in flour. Hexanal, decanal, butanoic acid, 2,3‐pentanedione, 2‐acetyl‐1‐pyrrolinoline, and 3‐octen‐2‐one were found to be the important aroma‐active compounds in flour by olfaction (O) in two‐dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC‐O‐MS). Dynamic headspace dilution analysis (DHDA), odour activity value (OAV), recombination and omission experiment further verified that these compounds can roughly simulate the overall aroma profile of flour. In this study, we determined the aroma‐active compounds in flour by molecular sensory science to improve the sensory preference of flour and enhance the quality of flour aroma, which will provide analytical ideas for future research on flour aroma and improve the production process.

Differences in volatile composition and expression of genes involved in terpenoids biosynthesis in Chrysanthemum indicum var. aromaticum

Chrysanthemum indicum var. aromaticum is an important ornamental plant in the genus Chrysanthemum, known for its unique and intense aroma. However, little is known about the composition of aroma components and their molecular regulatory mechanisms, which limits the development and utilization of Ci. var. aromaticum. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to analyze the aroma components of different organs (stem, leaf, and flower in different stages) of Ci. var. aromaticum. Meanwhile, the relative expression levels of key genes of terpenoid metabolism in different organs were determined by real-time quantitative PCR (qRT-PCR). Results showed that, a total of 128 volatiles were detected in 5 organs of Ci. var. aromaticum with more than 88.99% of terpenoids proportion, and 38 of the 128 were characteristic aroma compounds. Among the characteristic aroma compounds, 13 of them, including β-eudesmol, β-caryophyllene, zingiberene, α-bergamotene, α-curcumene, germacrene D, δ-cadinene, γ-terpinene, β-bisabolene, α-cubebene, aromandendrene, alloaromadendrene, and eucalyptol, formed the main aroma of Ci. var. aromaticum, and it was suggested that β-caryophyllene, zingiberene, eucalyptol, β-eudesmol, β-pinene, α-muurolene, and isocaryophyllene were responsible for the difference in aroma between the different organs of Ci. var. aromaticum. Combined with metabolomics, it was inferred that terpenoids such as β-eudesmol, cis-sabinol, α-thujone, α-thujene, etc. were involved in mevalonate (MVA) pathway; β-phellandrene, α-copaene, etc. were involved in methylerythritol phosphate (MEP) pathway. This study provided some theoretical guidance for further exploration of the aroma mechanism of Ci. var. aromaticum, which was helpful to the fully development and utilization of Ci. var. aromaticum resources.

Aromatic Profiling of New Table Grape Varieties Using Gas Chromatography/Mass Spectrometry and Olfactometry.

The aim of this study is the aromatic characterization of new table grape varieties, namely Guzun (V. vinifera), Melona (V. vinifera), Cotton Candy (V. vinifera), IVC SA3 (V. labrusca), and IVC SB1 (V. labrusca). The qualitative and quantitative analysis of odorant molecules present in the berries allows for the definition of the aroma profile of the grape. This analysis benefits from the progress of analytical techniques and sensory methodologies. Gas chromatography/mass detection enable the efficient detection of the substances present and their concentrations. Through the coupling of gas chromatography with sensory detection (gas chromatography-olfactometry), it is possible to correlate the compounds detected by gas chromatography with olfactory stimuli, exploiting the human olfactory system. Aroma, a significant flavor component, is an important attribute of table grape that contributes to defining their quality. This characteristic is highly valued by consumers, and consequently, the market asks for table grapes with a particular or new aroma. Aromatic characterization is a crucial step in the study of the table grape varieties to evaluate their potential at the commercial level or, for instance, in breeding programs focusing on organoleptic properties.