Aroma-active Components Research Articles

Approaches of aroma extraction dilution analysis (AEDA) for headspace solid phase microextraction and gas chromatography–olfactometry (HS-SPME–GC–O): Altering sample amount, diluting the sample or adjusting split ratio?

Aroma extract dilution analysis (AEDA) is widely used for the screening of aroma-active compounds in gas chromatography–olfactometry (GC–O). In this study, three aroma dilution methods, (I) using different test sample volumes, (II) diluting samples, and (III) adjusting the GC injector split ratio, were compared for the analysis of volatiles by using HS-SPME–AEDA. Results showed that adjusting the GC injector split ratio (III) was the most desirable approach, based on the linearity relationships between Ln (normalised peak area) and Ln (normalised flavour dilution factors). Thereafter this dilution method was applied in the analysis of aroma-active compounds in Japanese soy sauce and 36 key odorants were found in this study. The most intense aroma-active components in Japanese soy sauce were: ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl 4-methylpentanoate, 3-(methylthio)propanal, 1-octen-3-ol, 2-methoxyphenol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol, 2-phenylethanol, and 4-hydroxy-5-ethyl-2-methyl-3(2H)-furanone.

GC–MS–olfactometric characterization of the most aroma-active components in a representative aromatic extract from Iranian saffron (Crocus sativus L.)

Aroma and aroma-active compounds of Iranian saffron (Crocus sativus L.) were analyzed by gas chromatography–mass spectrometry–olfactometry. The saffron aromatic extracts were obtained by four different extraction techniques including solvent-assisted flavour evaporation (SAFE), liquid–liquid extraction (LLE), solid phase extraction (SPE), and simultaneous distillation extraction (SDE) and compared to achieve a representative aromatic extract from saffron. According to sensory analysis, the aromatic extract obtained by SAFE was the most representative of saffron odour. A total of 28 aroma compounds were identified in saffron. Ketones were quantitatively the most dominant volatiles in saffron, followed by aldehydes and acids. Aroma extract dilution analysis (AEDA) was used for the determination of aroma-active compounds of saffron. A total of nine aroma-active compounds were detected in the aromatic extract. On the basis of the flavour dilution (FD) factor, the most powerful aroma active compounds were safranal (FD=512), 4-ketoisophorone (FD=256) and dihydrooxophorone (FD=128).

Identification of character-impact odorants in a cola-flavored carbonated beverage by quantitative analysis and omission studies of aroma reconstitution models.

Thirty aroma-active components of a cola-flavored carbonated beverage were quantitated by stable isotope dilution assays, and their odor activity values (OAVs) were calculated. The OAV results revealed that 1,8-cineole, (R)-(-)-linalool, and octanal made the greatest contribution to the overall aroma of the cola. A cola aroma reconstitution model was constructed by adding 20 high-purity standards to an aqueous sucrose-phosphoric acid solution. The results of headspace solid-phase microextraction and sensory analyses were used to adjust the model to better match authentic cola. The rebalanced model was used as a complete model for the omission study. Sensory results indicated that omission of a group consisting of methyleugenol, (E)-cinnamaldehyde, eugenol, and (Z)- and (E)-isoeugenols differed from the complete model, while omission of the individual components of this group did not differ from the complete model. These results indicate that a balance of numerous odorants is responsible for the characteristic aroma of cola-flavored carbonated beverages.

Flavor chemistry of lemon-lime carbonated beverages.

The most potent aroma-active components of Sprite (SP), Sierra Mist (SM), and 7UP (7UP) were identified. Aroma extracts were prepared by liquid–liquid continuous extraction/solvent-assisted flavor evaporation (LLCE/SAFE). Twenty-eight compounds were detected by gas chromatography–olfactometry (GC-O) with linalool (floral, lavender), octanal (pungent orange), and 2,3-dehydro-1,8-cineole (minty) determined to be predominant aroma compounds based on their high flavor dilution (FD) factors by aroma extract dilution analysis (AEDA). The data indicate that lemon-lime flavor is composed of a small number of compounds (22 at the most in SM), and only a subset of these may be important because many compounds were detected only at low FD factors. Predominant aroma compounds (23) were quantified using static headspace solid phase microextraction (SPME) combined with stable isotope dilution assays (SIDA). In contrast to FD factors, the calculated odor-activity values (OAVs) indicate that octanal and limonene make the greatest contribution to the overall aroma of lemon-lime carbonated beverages, followed by nonanal, decanal, linalool, 1,8-cineole, and geranyl acetate. The results demonstrate that lemon-lime carbonated beverages share many of the same compounds but the relative abundance of these compounds varies by brand.

Characterization of potent odorant compounds in Turkish olive oils by GC-MS-olfactometric techniques

The purpose of this study was to determine the most powerful aroma-active compounds of olive oils obtained from Ayvalik (AYV), Gemlik (GEM) and Memecik (MEM) cultivars harvested in 2011, using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Simultaneous distillation and extraction (SDE) with dichloromethane was used for extraction of volatile components. The aroma-active compounds of olive oils were evaluated by aroma extract dilution analysis (AEDA). A total of 14, 12 and 12 aroma-active compounds within the range of ≥64–1024 flavor dilution (FD) factors were detected in aromatic extracts of olive oils obtained from AYV, GEM and MEM cvs., respectively. The compounds having the highest FD factor (1024) were ( Z )-3-hexenol (cut grass, herbal) and β-sesquiphellandrene (floral) for AYV oil and ( Z )-3-hexenyl acetate (fruity) for MEM oil. Among these compounds, terpenes were the overwhelmingly largest aroma-active components followed by aldehydes.

Characterization of potent odorant compounds in Turkish olive oils by GC-MS-olfactometric techniques

The purpose of this study was to determine the most powerful aroma-active compounds of olive oils obtained from Ayvalik (AYV), Gemlik (GEM) and Memecik (MEM) cultivars harvested in 2011, using gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Simultaneous distillation and extraction (SDE) with dichloromethane was used for extraction of volatile components. The aroma-active compounds of olive oils were evaluated by aroma extract dilution analysis (AEDA). A total of 14, 12 and 12 aroma-active compounds within the range of ≥64–1024 flavor dilution (FD) factors were detected in aromatic extracts of olive oils obtained from AYV, GEM and MEM cvs., respectively. The compounds having the highest FD factor (1024) were (Z)-3-hexenol (cut grass, herbal) and β-sesquiphellandrene (floral) for AYV oil and (Z)-3-hexenyl acetate (fruity) for MEM oil. Among these compounds, terpenes were the overwhelmingly largest aroma-active components followed by aldehydes.

Characterization of potent odorants in Thai chempedak fruit (Artocarpus integer Merr.), an exotic fruit of Southeast Asia

Chempedak (Artocarpus integer Merr.) is a native fruit in Malaysia, Indonesia and southern Thailand, and like jackfruit, belongs to the Moraceae family. The characteristic aroma-active components of two chempedak cultivars, Tongtapan and Sainumpung, grown in southern Thailand were analyzed by aroma extract dilution analysis (AEDA) combined with gas chromatography–olfactometry (GC–O) and gas chromatography–mass spectrometry (GC–MS). The predominant odorants [with flavor dilution (FD) factors>9] in both cultivars were 4-hydroxy-2,5-dimethyl-3(2H)-furanone (burnt sugar, sweet), 3-methylbutanal (dark chocolate), methional (cooked potato-like), and 2-acetyl-1-pyrroline (popcorn, jasmine), while ethyl 3-methylbutanoate (fruity) was predominant only in Tongtapan cultivar. Selected positively identified aroma-active compounds were further quantified using stable isotope dilution assays (SIDA) combined with GC–MS. On the basic of the quantitative data and odor thresholds, odor activity values (OAV) were determined. Aroma recombination models and omission models were constructed for both cultivars based on concentrations of odorants with high OAVs and then validated and characterized by sensory studies. Complete aroma recombination models of both chempedak cultivars were reconstituted and characterized by comparison with authentic chempedak fruits. Omission studies were performed to verify the significance of character-impact odorants in both chempedak cultivars. Based on sensory evaluation, 3-methylbutanal, octanal, and 2-acetyl-1-pyrroline were found to be important odorants in the overall aromas of both cultivars, while ethyl 3-methylbutanoate was an additional key odorant in the aroma of the Tongtapan cultivar.

Characterisation of aroma profiles of commercial soy sauce by odour activity value and omission test

Twenty-seven commercial soy sauces produced through three different fermentation processes (high-salt liquid-state fermentation soy sauce, HLFSS; low-salt solid-state fermentation soy sauce, LSFSS; Koikuchi soy sauce, KSS) were examined to identify the aroma compounds and the effect of fermentation process on the flavour of the soy sauce was investigated. Results showed that 129 volatiles were identified, of which 41 aroma-active components were quantified. The types of odorants occurring in the three soy sauce groups were similar, although their intensities significantly differed. Many esters and phenols were found at relatively high intensities in KSS, whereas some volatile acids only occurred in LSFSS. Furthermore, 23 aroma compounds had average OAVs>1, among which 3-methylbutanal, ethyl acetate, 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone, 2-methylbutanal and 3-(methylthio)propanal exhibited the highest average OAVs (>100). In addition, omission tests verified the important contribution of the products resulting from amino acid catabolism to the characteristic aroma of soy sauce.

Chemical composition and aroma evaluation of volatile oils from edible mushrooms (Pleurotus salmoneostramineus and Pleurotus sajor-caju).

This study is focused on the volatile oils from the fruiting bodies of Pleurotus salmoneostramineus (PS) and P. sajor-caju (PSC), which was extracted by hydrodistillation (HD) and solvent-assisted flavor evaporation (SAFE) methods. The oils are analyzed by gas chromatography-mass spectrometry (GC-MS), GC-olfactometry (GC-O), and aroma extract dilution analysis (AEDA). A total of 31, 31, 45, and 15 components were identified in PS (HD and SAFE) and PSC (HD and SAFE), representing about 80.3%, 92.2%, 88.9%, and 83.0% of the oils, respectively. Regarding the aroma-active components, 13, 12, 13, and 5 components were identified in PS (HD and SAFE) and PSC (HD and SAFE), respectively, by the GC-O analyses. The results of the sniffing test, odor activity value (OAV) and flavor dilution (FD) factor indicate that 1-octen-3-ol and 3-octanone are the main aroma-active components of PS oils. On the other hands, methional and 1-octen-3-ol were estimated as the main aroma-active components of PSC oils.

Comparison of Agitake (Pleurotus eryngii var. ferulae) Volatile Components with Characteristic Odors Extracted by Hydrodistillation and Solvent-assisted Flavor Evaporation

The chemical composition of volatile oil from agitake (Pleurotus eryngii var. ferulae) was established for the first time using gas chromatography (GC) and GC-mass spectrometry. Sixty-seven and 24 components were extracted by hydrodistillation (HD) using diethyl ether (DE) and dichloromethane (DM), respectively; these components accounted for 80.3% and 91.8% of the total oil, respectively. Thirteen and 48 components of were extracted by the solvent-assisted flavor evaporation method (SAFE), using DE and DM, respectively, and identified; these components accounted for 83.5% and 82.0% of the total oil, respectively. Methylsuccinimide and 2,3,7-trimethyl-2-octene were the most characteristic components by SAFE using DM.Odor evaluation of the volatile oil from agitake was also carried out using GC-olfactometry (GC-O), aroma extraction dilution analysis (AEDA), and the odor activity value (OAV). Sixteen, 8, 5 and 9 aroma-active components were identified using HD (DE and DM) and SAFE (DE and DM), respectively. The main aroma-active components extracted using HD and SAFE were 1-octen-3-ol (mushroom-like) and phenylacetaldehyde (floral), respectively. This study proved that HD and SAFE can be used as complementary extraction techniques for the complete characterization of volatile oil from agitake.

Characteristic odorants from bailingu oyster mushroom (Pleurotus eryngii var. tuoliensis) and summer oyster mushroom (Pleurotus cystidiosus).

In this study, the characteristic odorants of the volatile oils from Pleurotus species (P. eryngii var. tuoliensis and P. cystidiosus) were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and aroma extract dilution analysis (AEDA). A total of 52 and 54 components (P. eryngii var. tuoliensis and P. cystidiosus, respectively) were identified, representing about 98.8% and 85.1% of the volatile oils, respectively. The main components of the P. eryngii var. tuoliensis oil were palmitic acid (82, 38.0%), oleic acid (86, 25.0%) and linoleic acid (85, 9.7%). The main components of the P. cystidiosus oil, palmitic acid (82, 25.8%), indole (54, 9.1%) and myristic acid (77, 5.3%). Regarding the aroma components, 16 and 13 components were identified in the P. eryngii var. tuoliensis and P. cystidiosus oils respectively, by the GC-O analyses. The results of the sniffing test, odor activity value (OAV) and flavor dilution (FD) factor indicate that methional, 1-octen-3-ol and nonanal are the main aroma-active components of P. eryngii var. tuoliensis oil. On the other hands, dimethyl trisulfide and 1-octen-3-ol were estimated as the main aroma-active components of the P. cystidiosus oil.

Characterization of Aroma-active Compounds in Dry Flower of Malva sylvestris L. by GC-MS-O Analysis and OAV Calculations

In this study, the aroma-active compounds in the dried flower of Malva sylvestris L. were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), and gas chromatography-olfactometry (GC-O) and aroma extraction dilution analysis (AEDA). A light yellow oil with a sweet odor was obtained with a percentage yield of 0.039% (w/w), and 143 volatile compounds (89.86%) were identified by GC-MS. The main compounds were hexadecanoic acid (10.1%), pentacosane (4.8%) and 6,10,14-trimethyl-2-pentadecanone (4.1%). The essential oil consisted mainly of hydrocarbons (25.40%) followed by, alcohols (18.78%), acids (16.66%), ethers (5.01%) ketones (7.28%), esters(12.43%), aldehydes (2.30%) and others (2.00%). Of these compounds, 20 were determined by GC-O and AEDA, to be odor-active (FD (flavor dilution) factor ≥ 1). β-Damascenone (FD = 9, sweet), phenylacetaldehyde (FD = 8, floral, honey-like) and (E)-β-ocimene (FD = 8, spicy) were the most intense aroma-active compounds in M. sylvestris. In order to determine the relative contribution of each of the compounds to the aroma of M. sylvestris, odor activity values (OAVs) were used. β-Damascenone had the highest odor activity values (OAV) (50,700), followed by (E)-β-ionone (15,444) and decanal (3,510). In particular, β-damascenone had a high FD factors, and therefore, this compound was considered to be the main aroma-active components of the essential oil. On the basis of AEDA, OAVs, and sensory evaluation results, β-damascenone is estimated to be the main aroma-active compound of the essential oil.

New needle packed with polydimethylsiloxane having a micro-bore tunnel for headspace in-needle microextraction of aroma components of citrus oils

A novel in-needle microextraction (INME) for headspace sampling evaluated in this study has significantly higher extraction speed and the practical merits of a durable stainless steel needle to overcome some exposed fiber related drawbacks. A prototype stainless steel needle (Hamilton 90022, 22gauge bevel tip, 51mm length) packed with polydimethylsiloxane (PDMS, 0.413mm O.D., 10mm length) having a micro-bore (200μm I.D.) tunnel was prepared as a new INME device. This needle with a barrel and a plunger is then inserted and exposed into the headspace over the sample. Headspace sampling can be speeded up by an automatic reciprocating pump. The extraction parameters have been optimized along with the validation of method performance. The methodology has been applied for the analysis of volatile aroma active components emitted from eight kinds of citrus essential oils by GC-FID or GC/MS. The proposed method showed excellent linearity, reproducibility, and low detection limit. This solventless technique is simple to operate, inexpensive to fabricate, and provides a facile means for collecting and introducing volatile aroma active components of essential oils.

Characterization of volatile aroma-active compounds in Dangyooja (Citrus grandis Osbeck)

Volatile components in peel and flesh of Dangyooja (Citrus grandis Osbeck) were isolated by solvent-assisted flavor evaporation (SAFE) followed by analysis using gas chromatography-mass spectrophotometry (GC-MS). Twenty-four components, including 4 alcohols, 6 aldehydes, 14 terpene hydrocarbons, and 16 components, including 1 alcohol, 1 aldehyde, 8 terpene hydrocarbons, 4 aromatic compounds, and 2 hydrocarbons were found in peel and flesh of Dangyooja, respectively. Limonene and myrcene were dominant in both parts of Dangyooja, although more volatile components were detected in peel of Dangyooja. Aroma-active compounds in peel and flesh of Dangyooja were also evaluated by aroma extract dilution analysis. Geranial (pineapple-like) showed the highest flavor dilution factor, followed by citronellal (herbaceous) and α-pinene (pine tree-like). In contrast, α-pinene (pine tree-like) and myrcene (floral) were the major aroma-active components in flesh of Dangyooja.

Characterization of the aroma-active compounds in Daqu: a tradition Chinese liquor starter

Daqu is a fermentation starter and substrate complex that is used to initiate the solid fermentations for the production of Chinese liquor. The aroma of Daqu is one of the most important factors that influence the flavor of Chinese liquor. The objective of this study was to evaluate the potent aroma-active compounds in Daqu. Odorants of Daqu extracted by solvent-assisted flavor evaporation (SAFE) were investigated by gas chromatography–olfactometry (GC–O) system with two olfactometric methods: detection frequency (DF) method and aroma extract dilution analysis (AEDA). A total of 43 compounds were identified in Daqu. Thirty-eight aroma-active components were further detected among which 33 were identified. Among these compounds, 4 odorants seem to contribute actively to the aroma of Daqu: hexanal (green grass), unknown (no.u2, nutty, roasted), phenylacetaldehyde (floral, rose) and 4-ethyl guaiacol (clove, spicy).

Effects of ultraviolet light and ultrasound on microbial quality and aroma‐active components of milk

Heat treatment is the most common way to extend the shelf life of milk. However, alternative technologies such as ultraviolet (UV) light and ultrasound (US), which are non-thermal methods for processing milk, have been developed to replace heat treatment. These technologies do not have any adverse effects on the quality of milk. The major purpose of this study was to investigate the effects of UV and US on different micro-organism groups and aroma compounds in milk. Heat pasteurisation at 65 °C for 30 min was used as thermal control treatment. The growth of total coliform group bacteria, Escherichia coli and Staphylococcus spp. was completely reduced by UV treatment. Application of US was not sufficient to reduce the numbers of yeasts and moulds. In neutral/basic fractions, 3-methylthiophene (plastic), hexanal (grass) and 1-hexen-3-one (floral) were major volatiles in milk samples. UV had a major effect on total coliforms, E. coli and Staphylococcus spp., but US was not as effective as UV and heat treatment in reducing certain groups of micro-organisms. No major differences were observed in terms of aroma-active compounds and flavour of milk following the different treatments. However, some new volatiles and change in rheological properties were generated by UV and US treatments.

Headspace-solid phase microextraction coupled to gas chromatography–combustion-isotope ratio mass spectrometer and to enantioselective gas chromatography for strawberry flavoured food quality control

Authenticity assessment of flavoured strawberry foods was performed using headspace-solid phase microextraction (HS-SPME) coupled to gas chromatography–combustion-isotope ratio mass spectrometry (GC–C-IRMS). An authenticity range was achieved, investigating on the carbon isotope ratio of numerous selected aroma active volatile components (methyl butanoate, ethyl butanoate, hex-(2E)-enal, methyl hexanoate, buthyl butanoate, ethyl hexanoate, hexyl acetate, linalool, hexyl butanoate, octyl isovalerate, γ-decalactone and octyl hexanoate) of organic Italian fresh strawberries. To the author's knowledge, this is the first time that all these components were investigated simultaneously by GC–C-IRMS on the same sample. The results were compared, when applicable, with those obtained by analyzing the HS-SPME extracts of commercial flavoured food matrices. In addition, one Kenyan pineapple and one fresh Italian peach were analyzed to determine the δ 13C VPDB of the volatile components common to strawberry. The δ 13C VPDB values are allowed to differentiate between different biogenetic pathways (C 3 and CAM plants) and more interestingly between plants of the same CO 2 fixation group (C 3 plants). Additional analyses were performed on all the samples by means of Enantioselective Gas Chromatography (Es-GC), measuring the enantiomeric distribution of linalool and γ-decalactone. It was found that GC–C-IRMS and Es-GC measurements were in agreement to detect the presence of non-natural strawberry aromas in the food matrices studied.

Wine flavor and aroma

The perception of wine flavor and aroma is the result of a multitude of interactions between a large number of chemical compounds and sensory receptors. Compounds interact and combine and show synergistic (i.e., the presence of one compound enhances the perception of another) and antagonistic (a compound suppresses the perception of another) interactions. The chemical profile of a wine is derived from the grape, the fermentation microflora (in particular the yeast Saccharomyces cerevisiae), secondary microbial fermentations that may occur, and the aging and storage conditions. Grape composition depends on the varietal and clonal genotype of the vine and on the interaction of the genotype and its phenotype with many environmental factors which, in wine terms, are usually grouped under the concept of "terroir" (macro, meso and microclimate, soil, topography). The microflora, and in particular the yeast responsible for fermentation, contributes to wine aroma by several mechanisms: firstly by utilizing grape juice constituents and biotransforming them into aroma- or flavor-impacting components, secondly by producing enzymes that transform neutral grape compounds into flavor-active compounds, and lastly by the de novo synthesis of many flavor-active primary (e.g., ethanol, glycerol, acetic acid, and acetaldehyde) and secondary metabolites (e.g., esters, higher alcohols, fatty acids). This review aims to present an overview of the formation of wine flavor and aroma-active components, including the varietal precursor molecules present in grapes and the chemical compounds produced during alcoholic fermentation by yeast, including compounds directly related to ethanol production or secondary metabolites. The contribution of malolactic fermentation, ageing, and maturation on the aroma and flavor of wine is also discussed.

Identification of characteristic aroma-active compounds in steamed mangrove crab (Scylla serrata)

Mangrove crab (Scylla serrata) has delicate texture and flavor, high economic value, and is relatively easy to grow. With its total production reaching 177 million kg in 2008, mangrove crab has become one of the most important marine commercial crustaceans in China. The objective of this study was to evaluate the potent aroma-active compounds in steamed mangrove crab. Odorants of steamed crabmeat extracted by simultaneous steam distillation–solvent extraction were investigated by MS hyphenated to the GC–Olfactometry system with two olfactometric methods: detection frequency method and aroma extract dilution analysis. A total of 53 compounds were identified in steamed mangrove crab meat. 38 aroma-active components were further detected and 31 identified. The following 5 were the most important contributors to the aroma of steamed mangrove crab meat: 2,3-butanedione (creamy, caramel), 2,5-dimethylpyrazine (roasted, nutty), 3-methylbutanal (chocolate), 2-acetyl-1-pyrroline (popcorn, nutty), 2-acetylthiazole(roasted, sulfury).

Common aroma-active components of propolis from 23 regions of China

The study of propolis odorants by gas chromatography-olfactometry-mass spectrometry has rarely been put into practice until now. This study aimed to investigate the common odorants of 23 samples of Chinese propolis and analyse the relationship between the principal components and the regions where the samples had been obtained. By using dynamic headspace sampling, gas chromatography-olfactometry-mass spectrometry and two internal standards, the principal aroma-active components of 23 propolis samples were analysed qualitatively and quantitatively. The common aroma-active components were compared with each other by principal component analysis from concentration, odour activity value (OAV) and sensory evaluation score. The components with high OAVs were acetic acid, 2-phenylethyl acetate, and naphthalene, in decreasing order, which approximated the sensory evaluation scores. On the discrete-point map the first three principal components seemed to be grouped into three patterns, while four samples were outliers. The concentrations of aroma-active components were closely related to the regions from a discrete-point map by the first three principal components. It was confirmed that components with high concentrations did not always play important roles in odour contribution, for odour level was linked with their threshold. OAVs could reflect the level of odour exactly according to the approximate result from the comparison between OAVs and sensory evaluation scores.