Identification of the key aroma compounds in cocoa powder based on molecular sensory correlations

Isolation of the volatile fraction from cocoa powder (50 g; 20% fat content) by a careful extraction/distillation process followed by application of an aroma extract dilution analysis revealed 35 odor-active constituents in the flavor dilution (FD) factor range of 8-4096. Among them, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), 2- and 3-methylbutanoic acid (sweaty, rancid), dimethyl trisulfide (cooked cabbage), 2-ethyl-3,5-dimethylpyrazine (potato-chip-like), and phenylacetaldehyde (honey-like) showed the highest FD factors. Quantitation of 31 key odorants by means of stable isotope dilution assays, followed by a calculation of their odor activity values (OAVs) (ratio of concentration to odor threshold) revealed OAVs>100 for the five odorants acetic acid (sour), 3-methylbutanal (malty), 3-methylbutanoic acid, phenylacetaldehyde, and 2-methylbutanal (malty). In addition, another 19 aroma compounds showed OAVs>1. To establish their contribution to the overall aroma of the cocoa powder, these 24 compounds were added to a reconstructed cocoa matrix in exactly the same concentrations as they occurred in the cocoa powder. The matrix was prepared from deodorized cocoa powder, which was adjusted to 20% fat content using deodorized cocoa butter. The overall sensory evaluation of this aroma recombinate versus the cocoa powder clearly indicated that the 24 compounds represented the typical sweet, cocoa-like odor of the real sample.     

Changes in key aroma compounds of Criollo cocoa beans during roasting

Application of a comparative aroma extraction dilution analysis on unroasted and roasted Criollo cocoa beans revealed 42 aroma compounds in the flavor dilution (FD) factor range of 1-4096 for the unroasted and 4-8192 for the roasted cocoa beans. While the same compounds were present in the unroasted and roasted cocoa beans, respectively, these clearly differed in their intensity. For example, 2- and 3-methylbutanoic acid (rancid) and acetic acid (sour) showed the highest FD factors in the unroasted beans, while 3-methylbutanal (malty), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), and 2- and 3-methylbutanoic acid (sweaty) were detected with the highest FD factors in the roasted seeds. Quantitation of 30 odorants by means of stable isotope dilution assays followed by a calculation of odor activity values (ratio of the concentration/odor threshold) revealed concentrations above the odor threshold for 22 compounds in the unroasted and 27 compounds in the roasted cocoa beans, respectively. In particular, a strong increase in the concentrations of the Strecker aldehydes 3-methylbutanal and phenylacetaldehyde as well as 4-hydroxy-2,5-dimethyl-3(2H)-furanone was measured, suggesting that these odorants should contribute most to the changes in the overall aroma after roasting. Various compounds contributing to the aroma of roasted cocoa beans, such as 3-methylbutanoic acid, ethyl 2-methylbutanoate, and 2-phenylethanol, were already present in unroasted, fermented cocoa beans and were not increased during roasting.     

Characterization of the key odorants in raw Italian hazelnuts ( Corylus avellana L. var. Tonda Romana) and roasted hazelnut paste by means of molecular sensory science

The concentrations of 19 odorants, recently characterized by GC-olfactometry and aroma extract dilution analysis as the most odor-active compounds in raw hazelnuts, were quantitated by stable isotope dilution assays (SIDA). Calculation of odor activity values (OAV) on the basis of odor thresholds in oil revealed high OAVs, in particular for linalool, 5-methyl-4-heptanone, 2-methoxy-3,5-dimethylpyrazine, and 4-methylphenol. A model mixture in sunflower oil containing the 13 odorants showing OAVs above 1 in their natural concentrations resulted in a good similarity compared to the overall nut-like, fruity aroma of the raw hazelnuts. Quantitation of the 25 most odor-active compounds in roasted hazelnut paste by SIDA showed clear changes in the concentrations of most odorants, and formation of new odor-active compounds induced by the roasting process was observed. The highest OAVs were calculated for 3-methylbutanal (malty), 2,3-pentanedione (buttery), 2-acetyl-1-pyrroline (popcorn), and (Z)-2-nonenal (fatty), followed by dimethyl trisulfide, 2-furfurylthiol, 2,3-butanedione, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone. The aroma of a model mixture containing the 19 odorants with OAVs above 1 in their actual concentrations in the roasted nut material was judged to elicit a very good similarity to the popcorn-like, coffee-like, and sweet-smoky aroma of the roasted hazelnut paste. New SIDAs were developed for the quantitation of 5-methyl-4-heptanone, 5-methyl-(E)-2-hepten-4-one, 2-thenylthiol, and 3,5,5-trimethyl-2(5H)-furanone.     

Determination of key aroma compounds in the crumb of a three-stage sourdough rye bread by stable isotope dilution assays and sensory studies

An investigation of the volatile fraction of a freshly prepared sourdough rye bread crumb by means of the aroma extract dilution analysis (AEDA), followed by identification experiments, revealed 22 flavor compounds in the flavor dilution (FD) factor range of 128 to 2048. Quantitations performed by stable isotope dilution assays (SIDA) and a calculation of odor activity values (OAV; ratio of concentration to odor threshold) revealed the following as contributors to the overall crumb flavor: 3-methylbutanal (malty), (E)-2-nonenal (green, fatty), (E,E)-2,4-decadienal (fatty, waxy), hexanal (green), acetic acid (sour, pungent), phenylacetaldehyde (honey-like), methional (boiled potato-like), vanillin (vanilla-like), 2,3-butandione (buttery), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (spicy), and 2- and 3-methylbutanoic acid (sweaty). Using either citrate buffer, starch, or deodorized crumb as model matrixes, the typical malty and sour rye bread crumb flavor was reproduced by adding a mixture of 20 reference odorants in the "natural" concentrations as quantitatively determined in the fresh crumb.     

Characterization of the most odor-active compounds in an American Bourbon whisky by application of the aroma extract dilution analysis

Application of the aroma extract dilution analysis (AEDA) on the volatile fraction carefully isolated from an American Bourbon whisky revealed 45 odor-active areas in the flavor dilution (FD) factor range of 32-4096 among which (E)-beta-damascenone and delta-nonalactone showed the highest FD factors of 4096 and 2048, respectively. With FD factors of 1024, (3S,4S)-cis-whiskylactone, gamma-decalactone, 4-allyl-2-methoxyphenol (eugenol), and 4-hydroxy-3-methoxy-benzaldehyde (vanillin) additionally contributed to the overall vanilla-like, fruity, and smoky aroma note of the spirit. Application of GC-Olfactometry on the headspace above the whisky revealed 23 aroma-active odorants among which 3-methylbutanal, ethanol, and 2-methylbutanal were identified as additional important aroma compounds. Compared to published data on volatile constituents in whisky, besides ranking the whisky odorants on the basis of their odor potency, 13 aroma compounds were newly identified in this study: ethyl (S)-2-methylbutanoate, (E)-2-heptenal, (E,E)-2,4-nonadienal, (E)-2-decenal, (E,E)-2,4-decadienal, 2-isopropyl-3-methoxypyrazine, ethyl phenylacetate, 4-methyl acetophenone, alpha-damascone, 2-phenylethyl propanoate, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, trans-ethyl cinnamate, and (Z)-6-dodeceno-gamma-lactone.     

Identification and quantification of aroma-active components that contribute to the distinct malty flavor of buckwheat honey

Characteristic aroma components of buckwheat honey were studied by combined sensory and instrumental techniques. Relative aroma intensity of individual volatile components was evaluated by aroma extract dilution analysis (AEDA) of solvent extracts and by gas chromatography-olfactometry (GCO) of decreasing headspace samples (GCO-H). Results indicated that 3-methylbutanal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon), and (E)-beta-damascenone were the most potent odorants in buckwheat honey, with 3-methylbutanal being primarily responsible for the distinct malty aroma. Other important aroma-active compounds included methylpropanal, 2,3-butanedione, phenylacetaldehyde, 3-methylbutyric acid, maltol, vanillin, methional, coumarin, and p-cresol.     

Identification based on quantitative measurements and aroma recombination of the character impact odorants in a Bavarian Pilsner-type beer

Application of aroma extract dilution analysis on the volatiles isolated from a Bavarian Pilsner-type beer revealed 40 odor-active constituents in the flavor dilution (FD) factor range of 16-2048, among which ethyl octanoate, (E)-beta-damascenone, 2- and 3-methylbutanoic acid, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone showed the highest FD factor of 2048. After quantitation of the 26 odorants showing FD factors > or =128 by stable isotope dilution analysis and determination of their odor thresholds in water, odor acitivity values (OAVs) were calculated. The results indicated ethanol, (E)-beta-damascenone, (R)-linalool, acetaldehyde, and ethyl butanoate with the highest OAVs, followed by ethyl 2-methylpropanoate and ethyl 4-methylpentanoate, which was previously unknown in beer. Finally, the overall aroma of the beer could be mimicked for the first time by recombining 22 reference odorants in the same concentrations as they occurred in the beer using ethanol/water as the matrix.     

Characterization of the key aroma compounds in the beverage prepared from Darjeeling black tea: quantitative differences between tea leaves and infusion

By application of the aroma extract dilution analysis on the volatile fraction isolated from a black tea infusion (Darjeeling Gold Selection), vanillin (vanilla-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel), 2-phenylethanol (flowery), and (E,E,Z)-2,4,6-nonatrienal (oat-flake-like) were identified with the highest flavor dilution (FD) factors among the 24 odor-active compounds detected in the FD factor range of 4-128. Quantitative measurements performed by means of stable isotope dilution assays and a calculation of odor activity values (OAVs; ratio of concentration to odor threshold in water) revealed, in particular, the previously unknown tea constituent (E,E,Z)-2,4,6-nonatrienal as a key odorant in the infusion and confirmed the important role of linalool and geraniol for the tea aroma. An aroma recombinate performed by the 18 odorants for which OAVs > 1 were determined in their "natural" concentrations matched the overall aroma of the tea beverage. In the black tea leaves, a total of 42 odorants were identified, most of which were identical with those in the beverage prepared thereof. However, quantitative measurements indicated that, in particular, geraniol, but also eight further odorants were significantly increased in the infusion as compared to their concentration in the leaves.     

Aroma extract dilution analysis of Cv. Marion (Rubus spp. hyb) and Cv. Evergreen (R. laciniatus L.) blackberries

Cultivar Marion and Evergreen blackberry aromas were analyzed by aroma extract dilution analysis. Sixty-three aromas were identified (some tentatively) by mass spectrometry and gas chromatography-retention time; 48 were common to both cultivars, and 27 have not been previously reported in blackberry fruit. A comparison of cultivars shows that both have comparable compound types and numbers but with widely differing aroma impacts, as measured by flavor dilution (FD) factors. Ethyl 2-methylbutanoate, ethyl 2-methylpropanoate, hexanal, furanones (2,5-dimethyl-4-hydroxy-3-(2H)-furanone, 2-ethyl-4-hydroxy-5-methyl-3-(2H)-furanone, 4-hydroxy-5-methyl-3-(2H)-furanone, 4,5-dimethyl-3-hydroxy-2-(5H)-furanone, and 5-ethyl-3-hydroxy-4-methyl-2-(5H)-furanone), and sulfur compounds (thiophene, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylthiophene, and methional) were prominent in Evergreen (FD 512-2048). Except for ethyl 2-methylpropanoate, these same compounds were also prominent in Marion, but the FD factors varied significantly (FD 8-256) from Evergreen. The aroma profile of blackberry is complex, as no single volatile was unanimously described as characteristically blackberry.     

Aroma components of acid-hydrolyzed vegetable protein made by partial hydrolysis of rice bran protein

Hydrolyzed vegetable protein (HVP) was prepared from rice bran protein concentrate (RBPc) by partial hydrolysis with aqueous 0.5 N HCl at 95 degrees C for 12 or 36 h (H-RBPc-12 and H-RBPc-36, respectively). Aroma components of the RBPc and the HVPs were characterized by gas chromatography-olfactometry, gas chromatography-mass spectrometry, aroma extract dilution analysis, and calculation of odor activity values (OAVs). The predominant odorants in RBPc were 3-methylbutanal, hexanal, 2-aminoacetophenone, (E)-2-nonenal, phenylacetaldehyde, and beta-damascenone. Among these, the odor of 2-aminoacetophenone, present at 59 ng/g in RBPc, was reminiscent of the typical odor of RBPc. Most of the predominant odorants had higher log3FD factors in the H-RBPc-36 as compared to H-RBPc-12. Aroma impact compounds of H-RBPc-12 and H-RBPc-36 were 2-methoxyphenol (guaiacol), 4-hydroxy-2,5-dimethyl-3(2H)furanone, 3-hydroxy-4,5-dimethyl-2(5H)furanone (sotolon), vanillin, 3-methylbutanal, (E)-2-nonenal, 4-vinyl-2-methoxyphenol (p-vinylguaiacol), and beta-damascenone. Guaiacol had the highest OAV values of 2770 and 17650 in H-RBPc-12 and H-RBPc-36, respectively.     

Identification of characteristic aroma components of Thai fried chili paste

Three forms of Thai fried chili pastes (CP) were prepared, consisting of an unheated CP (UH-CP), a CP heated at 100 degrees C for 25 min (H25-CP, typical product), and a CP excessively heated for 50 min (H50-CP). The potent odorants in the CPs were investigated by two gas chromatography-olfactometry methods: dynamic headspace dilution analysis (DHDA) and aroma extract dilution analysis (AEDA). DHDA revealed that the predominant odorants in heated CPs were mainly sulfur-containing compounds, followed by lipid-derived compounds, Strecker aldehydes, and Maillard reaction products. Dimethyl sulfide, allyl mercaptan, 2- (or 3-) methylbutanal, ally methyl sulfide, 2,3-butanedione, 3,3'-thiobis(1-propene), and methyl propyl disulfide were among the most potent headspace odorants detected by DHDA. By AEDA, 2-vinyl-4 H-1,3-dithiin and diallyl trisulfide had the highest FD factors in H25-CP. On the basis of their high FD factors by both GCO methods, the predominant odorants in H25-CP were 3-vinyl-4 H-1,2-dithiin, allyl methyl disulfide, and allyl methyl trisulfide. Furthermore, dimethyl trisulfide and diallyl disulfide had the highest odor activity values in H25-CP, suggesting that these were also potent odorants in CP. In addition, methional, 3-methylbutanoic acid, 4-hydroxy-2,5-dimethyl-3-(2 H)-furanone, and 3-hydroxy-4,5-dimethyl-2( 5H)-furanone (sotolon) were indicated as potent thermally derived odorants of H25-CP.     

Characterization of the aroma-active compounds in pink guava (Psidium guajava, L.) by application of the aroma extract dilution analysis

The volatiles present in fresh, pink-fleshed Colombian guavas ( Psidium guajava, L.), variety regional rojo, were carefully isolated by solvent extraction followed by solvent-assisted flavor evaporation, and the aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis. The results of the identification experiments in combination with the FD factors revealed 4-methoxy-2,5-dimethyl-3(2 H)-furanone, 4-hydroxy-2,5-dimethyl-3(2 H)-furanone, 3-sulfanylhexyl acetate, and 3-sulfanyl-1-hexanol followed by 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, ( Z)-3-hexenal, trans-4,5-epoxy-( E)-2-decenal, cinnamyl alcohol, ethyl butanoate, hexanal, methional, and cinnamyl acetate as important aroma contributors. Enantioselective gas chromatography revealed an enantiomeric distribution close to the racemate in 3-sulfanylhexyl acetate as well as in 3-sulfanyl-1-hexanol. In addition, two fruity smelling diastereomeric methyl 2-hydroxy-3-methylpentanoates were identified as the ( R,S)- and the ( S,S)-isomers, whereas the ( S,R)- and ( R,R)-isomers were absent. Seven odorants were identified for the first time in guavas, among them 3-sulfanylhexyl acetate, 3-sulfanyl-1-hexanol, 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, trans-4,5-epoxy-( E)-2-decenal, and methional were the most odor-active.     

Quantitation of odor-active compounds in rye flour and rye sourdough using stable isotope dilution assays

Application of the aroma extract dilution analysis on a flavor distillate prepared from freshly ground rye flour (type 1150) revealed 1-octen-3-one (mushroom-like), methional (cooked potato), and (E)-2-nonenal (fatty, green) with the highest flavor dilution (FD) factors among the 26 odor-active volatiles identified. Quantitative measurements performed by stable isotope dilution assays and a comparison to the odor thresholds of selected odorants in starch suggested methional, (E)-2-nonenal, and hexanal as contributors to the flour aroma, because their concentrations exceeded their odor thresholds by factors >100. Application of the same approach on a rye sourdough prepared from the same batch of flour revealed 3-methylbutanal, vanillin, 3-methylbutanoic acid, methional, (E,E)-2,4-decadienal, 2,3-butanedione, and acetic acid as important odorants; their concentrations exceeded their odor thresholds in water and starch by factors >100. A comparison of the concentrations of 20 odorants in rye flour and the sourdough made therefrom indicated that flour, besides the fermentation process, is an important source of aroma compounds in dough. However, 3-methylbutanol, acetic acid, and 2,3-butanedione were much increased during fermentation, whereas (E,E)-2,4-decadienal and 2-methylbutanal were decreased. Similar results were obtained for five different flours and sourdoughs, respectively, although the amounts of some odorants in the flour and the sourdough differed significantly within batches.     

Identification of sulfur volatiles in canned orange juices lacking orange flavor

The purpose of this study was to understand why some canned orange juices are not perceived as orange juice. Sensory flavor profile data indicated that the primary odor (orthonasal) attributes were tropical fruit/grapefruit, cooked/caramel, musty, and medicine. By comparison fresh-squeezed juice lacked these odor attributes. GC-O analysis found 43 odor-active components in canned juices. Eight of these aroma volatiles were sulfur based. Four of the 12 most intense aroma peaks were sulfur compounds that included methanethiol, 1-p-menth-1-ene-8-thiol, 2-methyl-3-furanthiol, and dimethyl trisulfide. The other most intense odorants included 7-methyl-3-methylene-1,6-octadiene (myrcene), octanal, 2-methoxyphenol (guaiacol), 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone (homofuraneol), (E)-non-2-enal, (E,E)-deca-2,4-dienal, 4-hydroxy-3-methoxybenzaldehyde (vanillin), and alpha-sinensal. Odorants probably responsible for the undesirable sensory attributes included grapefruit (1-p-menth-1-ene-8-thiol), cooked [2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol), and 3-(methylthio)propanal (methional)], musty [7-methyl-3-methylene-1,6-octadiene and (E)-non-2-enal], and medicine (2-methoxyphenol). The canned juices also lacked several aldehydes and esters normally found in fresh orange juice.     

Aroma-active components of nonfat dry milk.

Application of aroma extract dilution analysis (AEDA) on the volatile components of low-, medium-, and high-heat-treated nonfat dry milks (NDM) revealed aroma-active compounds in the log(3) flavor dilution (log(3) FD) factor range of 1 to 6. The following compounds contributed the highest log(3) FD factors to overall NDM flavor: 2,5-dimethyl-4-hydroxy-3(2H)-furanone [(Furaneol), burnt sugar-like]; butanoic acid (rancid); 3-(methylthio)propanal [(methional), boiled potato-like]; o-aminoacetophenone (grape-like); delta-decalactone (sweet); (E)-4,5-epoxy-(E)-2-decenal (metallic); pentanoic acid (sweaty); 4,5-dimethyl-3-hydroxy-2(5H)-furanone [(sotolon), curry]; 3-methoxy-4-hydroxybenzaldehyde [(vanillin), vanilla]; 2-acetyl-1-pyrroline and 2-acetyl-2-thiazoline (popcorn-like); hexanoic acid (vinegar-like); phenylacetic acid (rose-like); octanoic acid (waxy); nonanal (fatty); and 1-octen-3-one (mushroom-like). The odor intensities of Furaneol, butanoic acid, methional, o-aminoacetophenone, sotolon, vanillin, (E)-4,5-epoxy-(E)-2-decenal, and phenylacetic acid were higher in high-heat-treated samples than others. However, the odor intensities of lactones, 2-acetyl-1-pyrroline, and 2-acetyl-2-thiazoline were not affected by heat treatment. Sensory evaluation results also revealed that heat-generated flavors have a major impact on the flavor profile of NDM.     

Identification of potent odorants formed during the preparation of extruded potato snacks

Extrusion cooking processing followed by air-drying has been applied to obtain low-fat potato snacks. Optimal parameters were developed for a dough recipe. Dough contained apart from potato granules 7% of canola oil, 1% of salt, 1% of baking powder, 5% of maltodextrin, and 15% of wheat flour. After the extrusion process, snacks were dried at 85 degrees C for 15 min followed by 130 degrees C for 45 min. The potent odorants of extruded potato snacks were identified using aroma extract dilution analysis and gas chromatography-olfactometry. Among the characteristic compounds, methional with boiled potato flavor, benzenemethanethiol with pepper-seed flavor, 2-acetyl-1-pyrroline with popcorn flavor, benzacetaldehyde with strong flowery flavor, butanal with rancid flavor, and 2-acetylpyrazine with roasty flavor were considered to be the main contributors to the aroma of extruded potato snacks. Several compounds were concluded to be developed during extrusion cooking, such as ethanol, 3-methylbutanal, (Z)-1,5-octadien-3-one with geranium flavor, and unknown ones with the flavor of boiled potato, cumin, candy, or parsley root. Compounds such as methanethiol, 2,3-pentanedione, limonene, 2-acetylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2-methyl-3,5-diethylpyrazine, 5-methyl-2,3-diethylpyrazine, and (E)-beta-damascenone were probably developed during air-drying of the potato extrudate.     

Change in the flavor of black tea drink during heat processing.

Heat processing during canning is responsible for the change in flavor of black tea infusion. The quantitative change in the volatile components of the black tea infusion during heat processing is not sufficient for explaining the sensory evaluation. In this study, application of aroma extract dilution analysis using the volatile fraction before and after black tea (Darjeeling) samples were heat processed resulted in the detection of 10 odor-active peaks for which flavor dilution (FD) factors changed. Seven potent odorants were identified from these peaks by gas chromatography-mass spectrometry. Among these components, 3-methylbutanal (stimulus), methional (potato-like), beta-damascenone (sweet), dimethyl trisulfide (putrid), and 2-methoxy-4-vinylphenol (clove-like) showed the highest FD factors after heat processing of the black tea sample. Therefore, these odorants were the most important components involved in changing the black tea odor during heat processing. In addition, the precursor of beta-damascenone in black tea infusion was investigated, and 3-hydroxy-7,8-didehydro-beta-ionol was determined to be one of the beta-damascenone-generating compounds for the first time.     

Comparison of the key aroma compounds in organically grown, raw West-African peanuts (Arachis hypogaea) and in ground, pan-roasted meal produced thereof

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.     

Studies on the key odorants formed by roasting of wild mango seeds (Irvingia gabonensis)

Application of the aroma extract dilution analysis on a concentrate of volatiles obtained by solvent extraction and high vacuum distillation from roasted seeds (180 degrees C; 15 min) of wild mango (Irvingia gabonensis) revealed 32 odor-active compounds with flavor dilution (FD) factors ranging from 8 (low odor activity) to 2048 (high odor activity). The identification experiments based on the use of reference odorants revealed methional (cooked potato-like) followed by 2-acetyl-1-pyrroline (roasty, popcorn-like), butan-2,3-dione, pentan-2,3-dione, 2-ethyl-3,5-dimethylpyrazine, and 2,3-diethyl-5-methylpyrazine as the key aroma compounds among the 27 odorants identified. All odorants are reported for the first time as components of roasted wild mango seeds.