Aroma Model Research Articles

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.

Yeast extracts weakened warmed-over flavor in surimi gels made from silver carp due to the masking effect by high concentrations of pyrazines and esters.

Warmed-over flavor (WOF) is an off-flavor in surimi gels. Yeast extract (YE) could improve the aroma properties of food. However, the effect of YE on the WOF in surimi gels and its mechanism was still unclear. In this study, aroma profiles, the composition of aroma compounds and aroma precursors, concentrations of WOF compounds, and thiobarbituric acid reactive substances (TBARS) of surimi gels with different amounts of YE were investigated by molecular sensory science and chromatographic techniques. Moreover, the effect of pyrazines and esters introduced by YE on WOF was also tested by sensory analysis. The addition of no less than 1% YE to surimi gels significantly weakened WOF. However, YE did not decrease the concentrations of WOF compounds and did not change the fatty acid composition and TBARS in surimi gels. Conversely, the addition of YE significantly increased the contents of free amino acids, N-containing compounds, and esters in surimi gels. The contents of total free amino acids, 2,6-dimethylpyrazine, and ethyl acetate in surimi gels with 2.5% YE were 1.5, 21, and 2.1 times higher than those in the control, respectively. Additionally, the sensory results of the spiked aroma models containing WOF compounds, 2,6-dimethylpyrazine, and esters showed that more than 9.4µg/kg of 2,6-dimethylpyrazine with a baked-potato note and more than 6.1µg/kg of ethyl acetate and 11.2µg/kg of butyl acetate with a fruity note could significantly mask WOF. In conclusion, WOF in surimi gels could be masked by YE due to the high concentrations of pyrazines and esters. Practical Application: Yeast extracts could decrease the warmed-over flavor (WOF) due to the high concentrations of pyrazines (baked-potato note) and esters (fruity note). This finding extends the application of yeast extracts in the food industry. On the other hand, this study presents a reasonable solution for the reduction of WOF in surimi products.

Characterization of key aroma compounds in low-salt fermented sour fish by gas chromatography-mass spectrometry, odor activity values, aroma recombination and omission experiments

In this study, key aroma compounds of low-salt fermented sour fish were characterized using headspace solid-phase micro extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC–MS), odor activity values (OAV) and aroma recombination and omission experiments. Eighty-eight volatile compounds, including esters, aldehydes, alcohols, acids, furans and pyrazines, were identified by HS-SPME-GC–MS. Eighteen aroma-active compounds were quantified by employing calculation of OAV greater than 1. A recombination aroma model prepared using aroma-active compounds based on the odorless fish matrix sensorially matched the aroma of fermented sour fish with a score of 4.5 out of 5. The omission experiment showed that 7 out of 18 compounds had a significant contribution to the overall aroma (P < 0.05). The key aroma compounds of fermented sour fish were concluded to be ethyl acetate (OAV = 189), ethyl hexanoate (OAV = 66), isoamyl acetate (OAV = 424), ethyl butyrate (OAV = 26), hexanal (OAV = 49), 1-hexadecanal (OAV = 14) and 2-pentylfuran (OAV = 13).

Heat transfer and aroma modeling of fresh fruit and vegetable in cold chain: Case study on tomatoes

Convective cooling/heating experiments were carried out using a device representing a half-layer of a pallet with four crates of tomatoes (var. Cauralina, Solanum Lycopersicum). Air and product temperatures were measured at different positions in the crates, which were exposed to several different ambient conditions in order to study the influence of air velocity, warming/cooling regimes, hole opening area and filming. The experimental results show that the product and air temperatures vary with the distance from the air inlet position. Since airflow rate was varied and controlled using fans equipped with electrical power variation, a correlation between the air velocity and the convective heat transfer coefficient was established. A transient state heat transfer model was developed based on a zonal approach, which considers overall thermo-physical properties for each crate. An aroma model was developed based on three hypothetic first order kinetics. The model takes into account the observation reported in several studies that tomato aroma decreases when the product temperature is lower than 12 °C and the aroma is recovered, but only partially, when the product temperature is higher than 12 °C. Finally, the thermal model was linked with the aroma model to predict the product temperature and the aroma evolution in two examples of supply chain scenario from producer cold room to consumption point. These numerical results show that the tomato variety and the product time-temperature history in a supply chain exert a significant influence on the aroma evolution.

Characterization of odour‐active compounds of sour guava (Psidium acidum[DC.]Landrum) fruit by gas chromatography‐olfactometry and odour activity value

AbstractVolatile compounds in sour guava (Psidium acidum [DC.] Landrum) were isolated by headspace‐solid‐phase microextraction (HS‐SPME) and solvent‐assisted flavour evaporation (SAFE). Analyses were performed by GC‐FID and GC‐MS. By GC‐O, the HS‐SPME extract was evaluated by frequency analysis, whereas the SAFE extract was assessed by aroma extract dilution analysis (AEDA) and odour activity value (OAV) to find the most odour‐active components. Twenty‐four volatiles were found as odour‐active compounds and contribute to the typical sour guava aroma, from which hexyl acetate, 3‐methylbutyl butanoate, (Z)‐3‐hexenyl acetate, (Z)‐3‐hexenyl hexanoate, nonanal and (E)‐β‐ionone presented the highest aroma contribution in sour guava fruit. Results demonstrated a good resemblance between the typical aroma of the fruit and the aroma model.

Odorants from the Thermal Treatment of Hydrolyzed Mushroom Protein and Cysteine Enhance Saltiness Perception.

Innovative approaches to develop flavors with high sensory appeal are critical in encouraging increased consumer preference and adoption of low sodium foods. Gas chromatography-olfactometry, coupled with stable isotope dilution assays and sensory experiments, led to the identification of the odorants responsible for an enhancement in saltiness perception of chicken broth prepared with thermally treated enzymatically hydrolyzed mushroom protein and cysteine, then reacted under kitchen-like cooking conditions. Comparative aroma extract dilution analysis revealed 36 odorants with flavor dilution factors between a range of 1 and 256. Sixteen odorants were quantitated and odor activity values (OAVs) calculated. Important odorants included 2-furfurylthiol (coffee, OAV 610), 1-(2-furyl)ethanethiol (meaty, OAV 78), 3-sulfanylpentan-2-one (catty, OAV 42), sotolon (maple, OAV 20), indole (animal, OAV 8), 2-methyl-3-(methyldithio)furan (meaty, OAV 3), and p-cresol (barnyard, OAV 1). An odor simulation model was evaluated in two consumer sensory studies. These studies confirmed that the addition of the aroma model increased the perceived saltiness of low sodium chicken broth (p < 0.05).

Comparison of the Aroma Profiles of Intermediate Wheatgrass and Wheat Bread Crusts.

The aroma profiles of bread crusts made from intermediate wheatgrass (Thinopyrum intermedium) and whole wheat (Triticum aestivum) flours were compared. Based on gas chromatography/mass spectrometry/olfactometry analysis, twenty-four odorants were identified and further quantified. The concentrations of seventeen compounds were significantly different between intermediate wheatgrass and whole wheat bread crusts, of which sixteen compounds were higher in the whole wheat sample. The aroma profiles of the bread samples were subsequently characterized using sensory descriptive analysis (DA) and indicated that the roasted attribute was perceived at a significantly higher intensity in the whole wheat sample due to a greater amount of Maillard reaction compounds. Alternatively, bran and green notes were perceived at higher intensities in the intermediate wheatgrass sample, however they were not attributed to the presence of specific compounds but rather to a change in the aroma composition. Aroma recombination DA of the whole wheat and intermediate wheatgrass aroma models was similar to the original aroma profiles of the bread samples, demonstrating the sensory relevance of the identified odorants.

Characterization of the Major Odor-Active Compounds in Jackfruit Pulp.

An aroma extract dilution analysis applied to the volatiles isolated from jackfruit ( Artocarpus heterophyllus Lam.) pulp by solvent extraction and solvent-assisted flavor evaporation resulted in the detection of 48 odorants with flavor dilution (FD) factors between 1 and ≥8192. Application of gas chromatography-olfactometry to static headspace samples revealed additional five highly volatile odorants. The structures of 44 out of the 53 detected odorants could be assigned. These 44 compounds were quantitated using stable isotopically substituted odorants as internal standards, and their odor activity values (OAVs) were calculated as the ratio of the natural concentrations in jackfruit pulp and the odor threshold values in water. High OAVs were in particular obtained for ethyl 3-methylbutanoate (74000), ethyl butanoate (1800), 3-methylbutanal (1500), and 2-methylpropanal (1400). An aroma model solution based on the natural concentrations of the 35 compounds for which OAVs > 1 had been calculated fully mimicked the characteristic jackfruit pulp aroma.

Identification of the aroma-active compounds in Longjing tea characterized by odor activity value, gas chromatography- olfactometry, and aroma recombination

ABSTRACTVolatile compounds in the three Longjing tea were analyzed by gas chromatography–mass spectrometry with method of solid phase microextraction–gas chromatography. Furthermore, aroma-active compounds of three Longjing tea were analyzed by gas chromatography–olfactometry and odor activity value. However, the kinds of aroma-active compounds identified from those two methods were different. The results showed that dihydroactinidiolide (aroma intensity = 9.1–9.2), (Z)-nerolidol (aroma intensity = 8.4–8.8), benzyl alcohol (aroma intensity = 8.1–8.4), and epoxylinalool (aroma intensity = 8.1–8.5) presented the highest aroma intensity in three green tea samples. While geraniol (422.4–2508.3), epoxylinalool (601.5–1033.9), (Z)-nerolidol (235.5–559.3), 2-ethyl-3,5-dimethylpyrazine (328.0–420.6), β-ionone (227.7–387.3) presented higher odor activity values than other compounds. Thus, this study uses recombination aroma models to identify selected important aroma-active compounds from gas chromatography–olfactometry and odor activity value and verifies their effectiveness to identify the aroma profile characterization of three Longjing tea samples using electronic nose analysis and sensory evaluation. The radar plot of electronic nose analysis tallied with sensory evaluation indicated that the odor activity value–based aroma models were more similar to the original Longjing tea aroma than gas chromatography–olfactometry–based models.

Determination of potential off-flavour in yeast extract

Yeast extracts is a kind of food ingredient for enhancing flavor, but some yeast extract samples had yeasty odour (off-flavour). The aim of this study was to detect key aroma compounds leading to the yeasty odour. Volatile compounds of 3 yeast extracts (with yeasty odour), FA and FB, LC were extracted by solid phase micro-extraction (SPME) and solvent assisted flavour evaporation (SAFE) respectively, and analysed by gas chromatography-olfactrometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA) techniques. Thirty aroma-active compounds were detected, among them 4-methylphenol, 3-methylpyridine, 3-methylbutanoic acid, propanoic acid with high FD factors (FD = 125, 125, 625, 125, ≥25), were identified as the key off-flavours responsible for yeasty and their accurate quantification were done by external standard method in SIM mode. Calculation of the OAVs revealed 3-methylbutanoic acid, 3-methylpyridine, 4-methylphenol as the key odourants in the extract. For the verification of analyzed off-flavours, sensory evaluations of aroma model were conducted by eight panelists, and the result showed that aroma recombinate had the yeasty odour profile similar with the original yeast extracts.The methods were successful for the detection of off-flavors in yeast extract and the four off-compounds analyzed were mainly responsible for the yeasty flavour.

Study on the application and preparation of aroma nanomaterials

The functional aroma materials (fragrance) have been widely applied in food, textile, leather, paper, cosmetic and detergents, which is close to the national economy and people life. At present, the researchs on the long released property and good smell aroma production technology has been focused. The perfuming requirement of 5 trillion RMB food, cosmetic and detergents should be satisfied with the fragrance technology. However, about 10 trillion RMB leather, paper and textile have been not applied in perfuming treatment. Therefore, the key scientific problem of the function mechanism between nano fragrance and fiber materials has been focused. The animal and plant fibers have rich nano-scale pores and structures. The dispersion, interaction function and the bonding property of aromatic molecules on the porous fibers and their sizes and surface properties would effect the quality of aromatic fibers. Based on the above problems, this project would solve the following problems: (1) the aroma synergism, (2) the controllable preparation of fragrance nanocapsules, and (3) the large-scale preparation and industrialization application of nano fragrance and the long-released aroma fibers. We will use many theories such as nanotechnology, perfume chemistry, interface chemistry and collagen chemistry to study the relationship between the natural porous fibers’ nanostructures and their surficial properties, the adsorption and desorption behaviors between nano fragrances and porous fibers. Then the interaction mechanism between nano fragrances and porous fibers and the aroma models with different threshold values have been built up. Different design and modification methods of nano potential aroma materials should be developed. Meanwhile, the self-assembly novel methods of the suited structure, controllable and long-sustained release nano fragrance would be studied on the focus of the different nanostructures of the fibers. The industrialization application technology of nano fragrance and the long sustained-release aroma fibres would also be studied and the corresponding product standards should be formed, aiming at the problem of the multi-scale effect and the unclear amplification rules. Therefore, this project would include four main research contents: (1) the interaction function and synergism mechanism between the nano-interface of the porous fibres and fragrance and nano fragrances, (2) the design of fragrance molecules and their aroma and released property control, (3) the study on the nano fragrance and their sustained-release properties, and (4) preparation and application of novel nano fragrance and nano capsules. Through this project, the large-scale preparation of fragrance nanocapsules can be extended. The aromatic application of nano fragrance in silk, leather and paper should be achieved. Finally, the aroma synergism and long release property of the aromatic productions can be primarily resolved. Therefore, the three guides of technology-production-standards of fragrance nanocapsules and aromatic fiber productions should be realized. The upgrading and updating of leather, textile and paper has been extended. Different productions of nano fragrance, aroma leather, silk and paper could be obtained. The professionalization and high level academic troops containing the different reseach fileds of nano science, perfume chemistry and light chemical engineering would be developed. In conclusion, the interaction mechanism between fragrance naocapsules and porous fibers can be revealed. Meanwhile, the preparation and application technology of fragrance nanocapsules and the long sustained-release aroma fibers should be developed to resolve the bottleneck problems of the fragrance industry. Finally, the core competiveness of the aromatic production in China can be enhanced. Provided that we can get the chance, the research development direction of the aromatic nanomaterials should be guided in the future.

Transfer across goatskin barrier of 2-butanone, 2,3-butanedione and 2-butanol during maturation of traditional Lebanese cheese, Darfiyeh: Comparison between experimental aqueous model solution and goatskin system

Darfiyeh cheese is a Lebanese traditional variety made from raw goat’s milk and ripened in goatskin. Ripening tools and conditions play the role of a barrier to protect the foodstuff against deterioration. This function requires the control of small volatile molecules transfer, such as aroma compounds.Several methods have been used for the measurement of diffusion of aroma volatile compounds. Few selected aroma compounds have been employed in more or less complex food model systems. Aqueous models containing some of the food components have been adopted as appropriate models given the complexity of food matrices.In this study, we characterized fragments of goatskin microbiologically, physico-chemically and qualitatively. Furthermore, we followed the transfer of three model aroma compounds (2-butanone, 2,3-butanedione and 2-butanol) in an experimental aqueous model solution/goatskin system at 20, 40 and 60 days of exposure.The barrier properties of goatskin were assessed for aroma model molecules through permeability and sorption tests. Therefore, the behavior/distribution of diffusing molecules was discussed on the basis of the physico-chemical properties of these molecules, the properties of the barrier material, as well as the food matrix (aqueous dilute model solution in the case of our study).Until 40 days, the transfer of model molecules was dependent on their physico-chemical properties and exposure time. After 60 days, the molecules tended to migrate from the goatskin back to the aqueous dilute model solution. In such a model, there was evidence of a tendency towards the diffusion of aroma model molecules in a cyclic way.

Aromatic effect of fat and oxidized fat on a meat‐like model reaction system of cysteine and glucose

AbstractIt is well known that lipid degradation modifies the aroma of the meat‐like reaction of cysteine and reducing sugars. However, how aroma modification is caused by the odourants produced in the reaction mixtures is rarely studied. In the present study, 76 volatiles were reported from the reaction models containing cysteine and glucose with (or without) chicken fat or oxidized chicken fat. Using aroma extract dilution analysis (AEDA) of gas chromatography‐olfactory (GC‐O), 15 potent odourants were screened, whereby 12 of them were identified and quantified to be 1~77889 µg/kg of the reaction mixtures. Aroma models, with similarity ratings to the reaction mixtures (by sensory analysis) ranging as high as 90%, were prepared. Sensory assessment by omission study showed that the presence of fatty compounds from lipid degradation in the reaction mixtures although of low FD factors by GCO, nonetheless contributed the greatest to the alteration of overall aroma, followed by the quantitative reduction of the thiols from the Maillard reaction. The quantitative change of the heterocyclic odourants which formed from the Maillard reaction or the interaction of the Maillard reaction with lipid degradation was found to have a marginal impact. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Identification, quantitation and sensory evaluation of methyl 2- and methyl 3-methylbutanoate in varietal red wines

Background and Aims Esters are the most important class of volatile compounds contributing to fruity and berry-like aroma notes in wine. In this study, we identified aroma-active compounds in Carmenere red wine with a focus on fruity smelling compounds. Methods and Results Application of an aroma extract dilution analysis to an aroma isolate obtained from Carmenere red wine by solvent-assisted flavour evaporation revealed, apart from well-known wine aroma compounds, two additional fruity smelling compounds, which were identified as methyl 2-methylbutanoate (M2MB) and methyl 3-methylbutanoate (M3MB). Quantitation of M2MB and M3MB in 16 different varietal red wines by stable isotope dilution assays resulted in a concentration below (M2MB) and close to or slightly above (M3MB) the respective odour threshold values. Spiking experiments based on a synthetic wine aroma model in combination with triangle tests did not result in significant sensory differences. Conclusions Methyl 2-methylbutanoate and M3MB are two novel volatile compounds that were identified in all red varietal wines. At the concentration found, they do not contribute significantly to the fruity aroma of these red wines. Significance of the Study This is the first report on the occurrence, concentration and sensory impact of M2MB and M3MB in red wines.

Elucidation of key aroma compounds in traditional dry fermented sausages using different extraction techniques

The use of different extraction techniques - solid phase microextraction (SPME) and solvent assisted flavour evaporation (SAFE) - can deliver different aroma profiles and it is essential to determine which is most suitable to extract the aroma compounds from dry fermented sausages. Forty-five aroma-active compounds were detected by SPME and SAFE, with 11 of them reported for the first time as aroma compounds in dry fermented sausages: ethyl 3-hydroxy butanoate, trimethyl pyrazine, D-pantolactone, isobutyl hexanoate, ethyl benzoate, α-terpineol, ethyl 3-pyridinecarboxylate, benzothiazole, 2,3-dihydrothiophene, methyl eugenol, γ-nonalactone. The aroma concentration and odour activity values (OAVs) were calculated. Flavour reconstitution analyses were performed using 20 odorants with OAVs above 1 obtained from the SAFE and SPME extracts to prepare the aroma model. SPME and SAFE techniques were complementary and necessary to reproduce the overall dry fermented sausage aroma. The final aroma model included the odorants from both extraction techniques (SPME and SAFE) but it was necessary to incorporate the compounds 2,4-decadienal (E,E), benzothiazole, methyl eugenol, α-terpineol, and eugenol to the final aroma model to evoked the fresh sausage aroma although a lowest cured meat aroma note was perceived.

Characterization of the Aroma of Central Otago Pinot noir Wines Using Sensory Reconstitution Studies

The aroma of two representative Pinot noir wines over two consecutive vintages from the Central Otago region of New Zealand underwent gas chromatography olfactory analysis. Forty-two odorants were identified in the aroma extract dilution analysis (AEDA) study with flavor dilution (FD) factors ranging from 3 to 19,683, with over 20 having FD > 81. The highest FDs were for phenylethyl alcohol (rose), ethyl isobutyrate (strawberry), β-damascenone (tea, floral), isovaleric acid (cheese), ethyl isovalerate (fruit, cherry), ethyl cinnamate (honey, cinnamon), and guaiacol (medicinal, smoky). Following AEDA studies, 51 compounds were quantified via GC–MS following liquid-liquid extractions, of which 22 were present at levels above perception threshold. The odorants with the highest odor activity values were β-damascenone, ethyl octanoate, ethyl hexanoate, ethyl isovalerate, isovaleric acid, and 3-mercapto-hexanol, with values ranging from 17 to 95. Using the data from these screening methods, aroma models were prepared by deodorizing two Pinot noir wines with LiChrolut EN resin and reconstituting the wines using purified aroma standards. Five further models for each wine were prepared in the same manner but with the omission of one major aroma family, and the models were presented to a trained panel. When compared to the fully reconstituted model, the omission treatments altered certain sensory descriptors, although overall no profound differences were observed and no genuine impact compounds were revealed.

Analysis and Sensory Evaluation of Jostaberry (Ribes x nidigrolaria Bauer) Volatiles

Volatiles of jostaberries (Ribes x nidigrolaria Bauer)--a hybrid of black currant (Ribes nigrum L.) and gooseberry (Ribes uva-crispa L.)--were isolated via vacuum headspace extraction and analyzed by capillary gas chromatographic methods for the first time. (E)-Hex-2-enal, (E)-hex-2-en-1-ol, (Z)-hex-3-enal, (Z)-hex-3-en-1-ol, methyl butanoate, ethyl butanoate, 2-methylbut-3-en-2-ol, and 1,8-cineol turned out to be the most dominant volatiles. The variability of the volatile profile was shown by the analysis of jostaberries harvested from different locations in Southern Germany and in different years. In addition to ripe jostaberries, underripe berries were also investigated and changes in the volatile profile were followed during the ripening process. By using sensory analysis, key aroma compounds were elucidated. An aroma model prepared by mixing most odor active compounds ((Z)-hex-3-enal, 1,8-cineol, ethyl butanoate, (E)-hex-2-enal, (E)-hex-3-enal, hexanal, pent-1-en-3-one, methyl butanoate, ethyl hexanoate, and oct-1-en-3-one) in their naturally occurring concentrations showed an overall aroma very similar to that of fresh jostaberries.

Formation of complex natural flavours by biotransformation of apple pomace with basidiomycetes

Altogether 30 different basidiomycetes were grown submerged in liquid culture media using seven different by-products of the food industry as the only carbon source. Seven fungus/substrate combinations revealed interesting flavour profiles. Culture supernatants of Tyromyces chioneus grown on apple pomace were extracted, and the aroma compounds were analysed by gas chromatography–olfactometry (GC–O). Potent odorants were identified by aroma extract dilution analysis (AEDA), calculation of the odour activity values (OAV), and proven by confection of an aroma model. 3-Phenylpropanal, 3-phenyl-1-propanol, and benzyl alcohol were identified as potent aroma biotransformation products. Headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME–GC–MS) experiments showed that 3-phenylpropanal, 3-phenyl-1-propanol, benzyl alcohol, methyl 3-phenylpropionate, methyl 2-phenylacetate, cinnamaldehyde and methyl cinnamate were produced during the cultivation period of eight days. By means of labelling experiments, (E)-cinnamic acid was identified as the precursor of 3-phenylpropanal and 3-phenyl-1-propanol. Basidiomycetes were able to biotransform food by-products to pleasant complex flavour mixtures.

Verification of Aroma Profiles of Jiashi Muskmelon Juice Characterized by Odor Activity Value and Gas Chromatography–Olfactometry/Detection Frequency Analysis: Aroma Reconstitution Experiments and Omission Tests

To verify the aroma profile of Jiashi muskmelon previously identified by gas chromatography-olfactometry/detection frequency analysis (GC-O/DFA) and odor activity value (OAV) calculation, the synthetic blends of odorants (aroma models) were prepared and then were compared with the original Jiashi muskmelon juice aroma using quantitative descriptive analysis (QDA) and electronic nose analysis (ENA), respectively. QDA and ENA both indicated that the model solution derived from OAV calculation more closely resembled the original melon juice aroma than that based on DFA data. Omission tests corroborated the significant contribution of five unsaturated aldehydes and alcohols with nine carbon atoms as well as five branched esters, in particular, the "fruity"-smelling ethyl butanoate and the "cucumber-like" (2E,6Z)-nona-2,6-dienal to Jiashi muskmelon overall aroma.

Perceptual Characterization and Analysis of Aroma Mixtures Using Gas Chromatography Recomposition-Olfactometry

This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to “cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the “reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola ‘Hidcote Blue’) as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of “lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor.