Characterization of the major aroma-active compounds in mango (Mangifera indica L.) cultivars Haden, White Alfonso, Praya Sowoy, Royal Special, and Malindi by application of a comparative aroma extract dilution analysis.

By application of a comparative aroma extract dilution analysis on the volatile fractions isolated by solvent extraction and solvent-assisted flavor evaporation (SAFE) from fresh raw Chinese ginger (Zingiber officinale Roscoe) and roasted ginger, 21 or 33 odorants, respectively, with flavor dilution (FD) factors in the range of 32-4096 were identified. In raw ginger, the highest FD factors were found for (E)-isoeugenol, 1,8-cineol, vanillin, geranial, and linalool. After roasting, in particular, the FD factors of 3-(methylthio)propanal (cooked potato-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (seasoning-like), and geraniol were substantially increased. The application of static headspace/olfactometry (SHO) on ground raw ginger revealed a high FD factor for highly volatile acetaldehyde which clearly decreased after roasting. By contrast, the SHO application revealed high FD factors for malty smelling methylpropanal and 3-methylbutanal, which both were exclusively detected in roasted ginger. Thirteen odorants, namely, decanoic acid, (Z)-2-decenal, (Z)-4-decenal, (E)-4,5-epoxy-(E)-2-decenal, (E)-4,5-epoxy-(E)-2-undecenal, fenchol, (Z)-3-hexenal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-methyl-2-buten-1-thiol, 2-methylpropanal, (E)-2-nonenal, and 1-nonen-3-one, were identified in ginger for the first time. Chiral analysis showed a much higher percent by weight portion for the (R)-enantiomer in citronellal, citronellol, and linalool, which was not much changed during pan-frying.

Lily bulbs (Lilium longiflorum Thunb.), known as ‘Bai He’ in Chinese, are a popular ingredient used in Asian cooking. Despite their popularity, little is known about the odorants responsible for their distinct aroma. The key aroma‐active compounds present in both raw and roasted lily bulbs were isolated by solvent extraction followed by solvent‐assisted flavour evaporation (SAFE) and gas chromatography–olfactometery (GC/O) analysis. A comparative aroma extract dilution analysis (cAEDA) in the flavour dilution (FD) factor range from ≥1 to 1024 resulted in 48 aroma‐active compounds reported in L. longiflorum bulbs for the first time. The highest FD factors in raw lily bulbs were determined for (E)‐hex‐3‐enal (green, FD 1024) and 3‐methylsulfanylpropanal (cooked potato‐like, FD 1024), followed by 2,2,4‐trimethyl‐3‐oxabicyclo[2.2.2]octane (eucalyptus‐like, FD 256) and 2‐phenyl acetaldehyde (floral, FD 256). Following roasting, odorants with high FD values in raw lily bulbs decreased in intensity. The thermal treatment resulted in the generation of 34 aroma‐active compounds. Aroma‐active compounds with FD factors of ≥1024 in roasted lily bulbs were identified as 1‐(3,4‐dihydro‐2H‐pyrrol‐5‐yl)ethan‐1‐one (roasty), 3‐methylsulfanylpropanal (cooked potato‐like), 2‐ethyl‐3,5‐dimethylpyrazine (earthy), 2,3‐diethyl‐5‐methylpyrazine (earthy), 3‐hydroxy‐4,5‐dimethyl‐2(5H)‐furanone (maple‐like), 2‐ethyl‐4‐hydroxy‐3‐methyl‐2H‐furan‐5‐one (maple‐like), and 2‐methoxy‐4‐[(E)‐prop‐1‐enyl]phenol (clove‐like). In summary, the aroma‐active compounds with high FD factors in raw lily bulbs decreased significantly as a result of roasting, and a new pool of aroma‐active compounds were formed during the roasting process.

The volatile compounds in commercial rums declared as aged 3, 7, 10, and 15 years were isolated by solvent extraction followed by solvent-assisted flavour evaporation and analysed by gas chromatography-olfactometry. According to the aroma extract dilution analysis, 19 potentially aroma-active compounds in the flavour dilution (FD) factor range of 8 to 1024 were found. Fifteen of them were present in at least one aged rum at FD factor≥128. Clear differences in the FD factors of these odourants between each of the aged rums suggested that they contributed to their unique sensory profiles.

The aroma profile of porcine fat from tainted boars, female pigs, and castrated male pigs was investigated by application of comparative aroma extract dilution analysis (cAEDA) on a SAFE distillate of volatiles prepared from porcine back fat samples. The AEDA resulted in a total of 16 aroma active compounds for boar fat with flavor dilution (FD) factors ranging from 2 to 2048, whereas 12 aroma active compounds were found in fat of female pigs and 14 in fat of castrated male pigs, both with FD factors ranging from 2 to 32. Odor activity values (OAVs) of key components for each fat were identified: In boar fat androstenone, skatole, indole, and 2-aminoacetophenone showed highest OAVs, whereas 2,5-dimethylpyrazine, 2,4-decadienal, and δ-decalactone showed highest OAVs in fat of female pigs. Fat of castrated male pigs showed highest OAVs for skatole, indole, 1-octen-3-ol and methional. Finally, the off-flavor attributes of boar fat were successfully simulated by a recombinant of all odorants at their natural concentration level in deodorized sunflower oil.

Application of an aroma extract dilution analysis on an aroma distillate prepared from organically grown, raw West-African peanuts (Cameroon) revealed 36 odor-active areas in the flavor dilution (FD) factor range of 1 to 2048. The identification experiments, which were all performed by using the respective reference chemicals, revealed 2-isopropyl-3-methoxypyrazine (earthy, pea-like), 2-isobutyl-3-methoxypyrazine (bell pepper-like, earthy), and trans-4,5-epoxy-(E)-2-decenal (metallic) with the highest FD factors among the 36 aroma compounds identified. The two last mentioned odorants and another set of 22 further odorants were identified for the first time in raw peanuts. A comparative aroma extract dilution analysis applied on distillates prepared from either the raw peanuts or ground peanut meal roasted in a pan showed 52 odor-active areas in the FD factor range of 8 to 2048 in the roasted nut material. The identification experiments in combination with the FD factors revealed that among them, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone showed the most significant contribution to the overall aroma, followed by 1-octen-3-one, 2-isopropyl-3-methoxypyrazine, (E, E)-2,4-decadienal, and trans-4,5-epoxy-(E)-2-decenal. As a further result, 20 aroma compounds were newly identified in roasted peanuts, such as 2-propionyl-1-pyrroline and 2-acetyltetrahydropyridine (both popcorn-like). In particular, 2-acetyl-1-pyrroline and 4-hydroxy-2,5-dimethyl-3(2 H)-furanone showed the most pronounced increase after roasting.

Application of an aroma extract dilution analysis to the volatiles isolated from sweet, fruity, and slightly turpentine-like smelling Spondias mombin L. fruit pulp by solvent extraction and solvent-assisted flavour evaporation afforded 39 aroma-active compounds with flavour dilution (FD) factors ranging from 4 to 1024, 33 of which were identified and eight that had not been reported in S. mombin fruit before. The highest FD factors were obtained for ethyl butanoate (fruity; FD 1024), 3-methylbutyl acetate (fruity, banana-like; FD 512), and 4-hydroxy-2,5-dimethylfuran-3(2H)-one (sweet, caramel-like; FD 512). High FD factors were also found for α-pinene (resinous), ethyl 3-methylbutanoate (fruity), myrcene (geranium leaf-like), ethyl hexanoate (fruity), (3Z)-hex-3-en-1-ol (green, grassy), methyl 3-hydroxybutanoate (fruity), linalool (citrusy), trans-calamenene (clove-like, herbaceous), 2-phenylethanol (flowery), and vanillin (vanilla-like) (all FD 256). Data suggest that the sweet and fruity aroma of S. mombin fruit pulp is mainly caused by a group of potent aroma-active esters including ethyl butanoate, 3-methylbutyl acetate, ethyl 3-methylbutanoate, ethyl hexanoate, and methyl 3-hydroxybutanoate, in combination with sweet, caramel-like smelling 4-hydroxy-2,5-dimethylfuran-3(2H)-one, whereas the turpentine-like note is primarily due to α-pinene and myrcene.

The volatiles isolated from samples of the special flavor hop varieties, Huell Melon and Polaris, and from the aroma hop variety, Hallertau Tradition, by solvent extraction and solvent-assisted flavor evaporation (SAFE) were subjected to a comparative aroma extract dilution analysis (cAEDA), which resulted in 46 odor-active compounds in the flavor dilution (FD) factor range of 16 to 2048. On the basis of high FD factors, myrcene, (3R)-linalool, and 2- and 3-methylbutanoic acid were confirmed as important variety-independent hop odorants. (1R,4S)-Calamenene was identified for the first time as an odor-active compound in hops. Clear differences in the FD factors and their subsequent objectification by stable isotope dilution quantitation suggested that high concentrations of the esters ethyl 2-methylbutanoate, ethyl 2-methylpropanoate, and propyl 2-methylbutanoate cause the characteristic fruity, cantaloupe-like odor note in Huell Melon hops, whereas the fruity and minty odor notes in Polaris are associated with high amounts of 3-methylbutyl acetate and 1,8-cineole.

To compare the changes of potent odorants (PO) in high‐salt liquid‐state fermentation soy sauce (HLFSS) after sterilization under 120°C for 15 s, the volatiles in HLFSS were isolated by solvent extraction combined with solvent‐assisted flavour evaporation and were analysed by gas chromatography‐mass spectrometry‐olfactometry. A total of 40 odour‐active compounds were identified, and their flavour dilution (FD) factors ranging from 1 to 4096 were determined by comparative aroma extract dilution analysis. Twenty‐four compounds with FD factors ≥8 were quantitated by establishing standard curves, and the results showed that total concentrations of alcohols and phenols were almost unchanged, those of esters, acids and pyrazines decreased and those of aldehydes and ketones increased. Based on quantitative results and thresholds in water, odour activity values (OAVs) were calculated. Eighteen compounds with OAVs ≥1 were determined as PO in HLFSS. The number of POs did not change after sterilization, and OAVs of 10 POs remained unchanged or varied very little. The significant changes in the concentrations of methional, 5‐ethyl‐4‐hydroxy‐2‐methyl‐3(2H)‐furanone, nonanal, ethyl 2‐methylbutanoate, methionol, benzeneacetaldehyde, 4‐hydroxy‐2,5‐dimethyl‐3(2H)‐furanone and 2‐ethyl‐3,5‐dimethylpyrazine after sterilization caused the obvious variations of OAVs, which made cooked potato, caramel‐like, fatty and floral notes in HLFSS change in different degrees. The results obtained have some reference value to produce SS.

Aroma-active compounds in northern highbush blueberries "Bluecrop" (Vaccinium corymbosum "Bluecrop") and "Elliott" (Vaccinium corymbosum "Elliott") were isolated using solvent extraction followed by solvent-assisted flavor evaporation. The aroma-active compounds were compared by aroma extract dilution analysis (AEDA) on a polar and a chiral column and odor activity values (OAVs). The results showed that both cultivars had similar aroma-active compounds, but the flavor dilution (FD) factors and OAV values varied, responsible for the subtle aroma differences. AEDA (FD ≥ 64) suggested that the important aroma-active compounds in both cultivars could be ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, (Z)-3-hexenal, 1-octen-3-one, (Z)-3-hexen-1-ol, methional, linalool, (E,Z)-2,6-nonadienal, 2-methylbutanoic acid, α-terpineol, (E,E)-2,4-nonadienal, β-damascenone, geraniol, geranyl acetone, o-cresol, eugenol, and vanillin. Different isomers can have different sensory thresholds and attributes. Enantiomer analysis revealed that although S-(+)-linalool was dominant in blueberry, R-(-)-linalool had a higher FD value and OAVs than that of the (S)-isomer. The S-(-)-α-terpineol was slightly elevated than R-(+)-α-terpineol in both cultivars.

An investigation by using an aroma extract dilution analysis (AEDA) of the aroma concentrates made from freshly roasted in-shell peanuts and stored peanuts revealed a total of 43 key aroma compounds, including 8 newly identified compounds in peanuts. Among them, 2-isobutyl-3-methoxypyrazine, exhibiting an earthy note, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone, exhibiting a caramel-like note, were detected with the highest flavor dilution (FD) factor of 4096 in the fresh peanuts, followed by 3,5-dimethyl-2-ethylpyrazine, exhibiting a nutty note, as having the next highest FD factor of 1024. A quantitative analysis of the key aroma compounds having high FD factors in the fresh peanuts and stored peanuts revealed that 2-methyl-3-furanthiol, 2-acetyl-1-pyrroline, 2-propionyl-1-pyrroline, and 3,5-dimethyl-2-vinylpyrazine significantly decreased during storage, while methyl 2-methyl-3-furyl disulfide, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, and 2-methoxy-4-vinylphenol significantly increased. The sensory experiments revealed that the fresh peanuts presented strong roasty/meaty, popcorn-like, and nutty notes, as well as moderate spicy/burnt and caramel-like notes, whereas the stored peanuts presented significantly weak roasty/meaty and popcorn-like notes and a significantly strong spicy/burnt note. Based on the comparative AEDAs, the quantitative analysis, and the sensory analysis, it was concluded that the freshly roasted peanut aroma comprised the significant contributions of 2-methyl-3-furanthiol exhibiting a roasty/meaty note, and of 2-acetyl-1-pyrroline and 2-propionyl-1-pyrroline exhibiting a popcorn-like note, and the lesser contribution of 2-methoxy-4-vinylphenol exhibiting a spicy/burnt note. In particular, 2-methyl-3-furanthiol, which was only detected in the freshly roasted peanut aroma concentrate, might be an essential component describing the freshness of the roasted peanut aroma by its diffusive roasty/meaty note.

Two rums differing in their overall aroma profile and price level (rum A, high price; rum B, low price) were analyzed by means of the Sensomics approach. Application of aroma extract dilution analysis (AEDA) on a distillate of volatiles prepared from rum A revealed 40 aroma-active compounds in the flavor dilution (FD) factor range from 8 to 2048. The identification experiments indicated cis-whiskey lactone, vanillin, decanoic acid, and 2- and 3-methylbutanol with the highest FD factors. The AEDA of a distillate prepared from rum B showed only 26 aroma-active compounds in the same FD factor range. Among them, in particular, ethyl butanoate, 1,1-diethoxyethane, ethyl (S)-2-methylbutanoate, and decanoic acid appeared with the highest FD factors. Thirty-seven compounds having at least an FD factor ≥32 in one of the two rums were quantitated using stable isotope dilution assays or enzyme kits (2 compounds). The calculation of odor activity values (OAVs; ratio of concentration to respective odor threshold) indicated ethanol, vanillin, ethyl (S)-2-methylbutanoate, and (E)-β-damascenone with the highest OAVs in rum A, whereas ethanol, 2,3-butanedione, 3-methylbutanal, and ethyl butanoate revealed the highest OAVs in rum B. Most compounds were present in similar concentrations in both rums, but significant differences were determined for vanillin, cis-whiskey lactone, and 4-allyl-2-methoxyphenol (all higher in rum A) and 3-methylbutanal, 2,3-butanedione, and ethyl butanoate (all higher in rum B). Finally, the aromas of both rums were successfully simulated by a recombinate using reference odorants in the same concentrations as they naturally occurred in the spirits.

Insight into the comparison of key aroma-active compounds between camellia oils from different processing technology

Beijing douzhi (BD) is a traditional snack in Beijing, China, and it has been listed as a part of Beijing's intangible cultural heritage. The potent odorants that contribute to the characteristic aroma of BD were investigated by analyzing the isolates from solvent-assisted flavor evaporation (SAFE) and simultaneous distillation-extraction. Using aroma extract dilution analysis based on gas chromatography-mass spectrometry and gas chromatography-olfactometry, 31 aroma-active compounds with flavor dilution (FD) factors ranging from 1 to 2187 were identified by comparison of their odor characteristics, MS data, and retention indices with those of reference compounds. To further determine their contribution to the aroma of BD, the odorants isolated using SAFE with FD factors ≥9 were quantified, and their odor activity values (OAVs; ratio of concentration to the respective odor threshold in water) were calculated. Eleven compounds were found to have OAVs ≥ 1, which indicated they were the potent odorants that contributed substantially to the characteristic aroma of BD. Among the 11 odorants, (E,Z)-2,6-nonadienal, eugenol, methional, p-cresol, 1-octen-3-one, and 3-methylbutanoic acid were not previously identified in BD.

Using solvent extraction followed by solvent-assisted flavour evaporation (SAFE), the volatile fraction from fruit of three hardy kiwi cultivars Actinidia arguta ‘Ananasnaya’, A. arguta ‘Bojnice’, and A. arguta ‘Dumbarton Oaks’ as well as from fruit of the common kiwi cultivar A. deliciosa ‘Hayward’ was isolated. Application of aroma extract dilution analysis (AEDA) to the volatile isolates afforded a total of 53 aroma-active compounds in the flavour dilution (FD) factor range of 1–8192, 14 of which are reported for the first time in kiwifruit. Results suggested that high amounts of green, grassy smelling (3Z)-hex-3-enal (FD 1024) in combination with low amounts of fruity smelling ethyl butanoate (FD 4) accounted for the typical aroma profile of Hayward kiwifruit, whereas the intense fruitiness of the hardy kiwifruit was associated with high amounts of ethyl butanoate (FD 1024 to 8192) and lower (FD 128 in Ananasnaya) to negligible amounts (FD < 1 in Bojnice) of (3Z)-hex-3-enal. The floral note of A. arguta ‘Bojnice’ and ‘Dumbarton Oaks’ could be linked to methyl and ethyl benzoate, which were not detected among the aroma-active compounds in A. deliciosa ‘Hayward’ and A. arguta ‘Ananasnaya’.

The volatiles isolated by solvent extraction and solvent-assisted flavor evaporation (SAFE) from roasted barley tea, prepared from either hulled barley or naked barley, were subjected to a comparative aroma extract dilution analysis, which resulted in 27 odor-active compounds with flavor dilution factors (FD factors) of 64-1024. An additional 5 odorants were detected by static headspace analysis. Quantitation of these 32 compounds revealed 22 and 23 odorants in the naked barley tea and in the hulled barley tea, respectively, that exceeded their odor-threshold values. On the basis of these data, the aromas of both barley tea variants were successfully reconstituted with reference compounds. The calculation of odor-activity values (OAVs = concentration/odor-threshold value) and omission tests suggested 2-methoxyphenol (OAVs 69 and 160) and trans-isoeugenol (OAVs 1.4 and 31) as key compounds responsible for the stronger smoky note in the hulled barley tea. Further important odorants in the naked and hulled barley teas included 2-acetylpyrazine (OAVs 23 and 16), 2-acetyl-1-pyrroline (OAVs 19 and 16), and 3-methylbutanal (OAVs 12 and 15).