Key Odorants Research Articles

Dynamic Changes in Volatile Compounds of Shaken Black Tea during Its Manufacture by GC × GC-TOFMS and Multivariate Data Analysis.

Changes in key odorants of shaken black tea (SBT) during its manufacture were determined using headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS) and multivariate data analysis. A total of 241 volatiles was identified, comprising 49 aldehydes, 40 esters, 29 alcohols, 34 ketones, 30 aromatics, 24 alkenes, 17 alkanes, 13 furans, and 5 other compounds. A total of 27 volatiles had average relative odor activity values (rOAVs) greater than 1, among which (E)-β-ionone, (E,Z)-2,6-nonadienal, and 1-octen-3-one exhibited the highest values. According to the criteria of variable importance in projection (VIP) > 1, p < 0.05, and |log2FC| > 1, 61 discriminatory volatile compounds were screened out, of which 26 substances were shared in the shaking stage (FL vs. S1, S1 vs. S2, S2 vs. S3). The results of the orthogonal partial least squares discriminate analysis (OPLS-DA) differentiated the influence of shaking, fermentation, and drying processes on the formation of volatile compounds in SBT. In particular, (Z)-3-hexenol, (Z)-hexanoic acid, 3-hexenyl ester, (E)-β-farnesene, and indole mainly formed in the shaking stage, which promoted the formation of the floral and fruity flavor of black tea. This study enriches the basic theory of black tea flavor quality and provide the theoretical basis for the further development of aroma quality control.

Use of egg yolk phospholipids as well as alanine and glucose to generate the key odorants of fried battered and breaded fish nuggets

Deep-fat fried battered and breaded foods are worldwide popular foods. In this study, egg yolk phospholipids, as well as alanine and glucose were used to generate the key odorants of fried coatings. The volatile compounds of fried coatings were extracted and analyzed by HS-SPME-GC-MS, and aroma profiles were analyzed via quantitative descriptive analysis. The results showed that the characteristic deep-fat frying odorants derived from Maillard reaction and lipids, such as methional, 2-methylbutanal and 3-methylbutanal, 2-ethyl-3,5-dimethylpyrazine, 2,4-decadienals, etc. were the highest amounts in the phospholipids & alanine and glucose treated sample, whereas the lowest in the control sample. Meanwhile, the aroma attributes had the same tendency as those of the odorants. The results proved that egg yolk phospholipids combined with alanine and glucose could be used to generate the key odorants of fried battered and breaded foods and enrich the volatile profile with a variety of Maillard reaction odorants. This treatment has a great potential use in catering industry.

Bioactive compounds from Cucumis melo L. fruits as potential nutraceutical food ingredients and juice processing using membrane technology.

The present study was designed to evaluate the nutritional composition of melon pulp Maazoun variety, in order to explore its potential attitude as a natural source of nutrients and bioactive molecules. The chemical characterization showed that the pulp was rich in moisture, carbohydrate, dietary fibers, and minerals, as well as carotenoids and phenolic compounds. The chromatographic analysis indicated that amentoflavone (16.14 mg/100 g) and gallic acid (13.56 mg/100 g) were the most abundant phenolic compounds. Melon flesh has an interesting volatile profile in which, mostly esters and alcohols are considered as the key odorants of this appreciated fruit. Melon juice was filtered through crossflow microfiltration that provides more translucent juice and accentuation of yellow color. During clarification process, the permeate flux was reduced by 50% in approximately 40 min. Results proved that the richness of melons in nutrients and bioactive phytochemicals makes them useful as a potential source of antioxidants and suitable as nutraceutical supplements.

Assessing the contribution of odor-active compounds in icewine considering odor mixture-induced interactions through gas chromatography–olfactometry and Olfactoscan

The sensory impact of odor-active compounds on icewine aroma could be influenced by perceptual interactions with other odor-active compounds. The aim of this study was to establish an approach to evaluate the contribution of odor-active compounds found in icewine considering mixture-induced perceptual interactions. By comparing the impact of key odorants detected in icewine following a gas chromatography–olfactometry approach with an Olfactoscan-based methodology using a background odor of icewine, 69 odor zones were detected, and their related compounds were further identified. The results revealed that icewine background odor could exert odor masking or enhancement on key odorants when they are considered in the complex wine aroma buffer. Several compounds can induce qualitative changes in the overall wine aroma. This study underlined the efficiency of Olfactoscan-like approaches to screen for the real impact of key odorants and to pinpoint specific compounds that could be highly influential once embedded in the aroma buffer.

Effect of gamma-irradiation and extrusion on the physicochemical, thermal and aroma-active compounds of rice flour

Food irradiation seems to be an effective and safe method for preventing microbial and insect contamination in cereals. Interestingly, the determination of the aroma-active compounds in irradiated and extruded rice flour does not yet exist. This study aimed to investigate aroma and aroma-active compounds of non-irradiated rice flour (NIRF) and irradiated and processed rice flour (IPRF) by the SPME method combined with GC-MS-O. In the present study, twenty-three aroma-active compounds in the NIRF sample while fifteen in the IPRF sample were identified with 1.6–4.9 odor intensity scores. Hexanal [4.9], nonanal [4.4], heptanal [3.9], decanal [3.3], 3-Octen-2-one [3.1] and were detected as key odorants in all samples. Whereas, 2-penthylfuran [3.8], octanal [3.8], nonanal [4.5], and benzaldehyde [2.1] were clearly higher in the IPRF sample, considering NIRF. The amount of hexanal which can be considered as irradiation odor (IO), has been increased due to the food irradiation process.

Comparison of key aroma‐active composition and aroma perception of cold‐pressed and roasted peanut oils

SummaryThe difference in the aroma composition of cold‐pressed and roasted peanut oils was investigated. There were 28 and 75 odorants with flavour dilution (FD) factors between 1 and 512 in cold‐pressed and roasted peanut oils, respectively. Fifty‐nine odorants were newly identified in peanut oils. Ten key odorants with odour activity value (OAV) ≥ 1 were identified in cold‐pressed peanut oil, of which hexanal (OAV = 1,288, green), (E,E)‐2,4‐decadienal (OAV = 370, earthy and fried fat) and α‐pinene (OAV = 34, woody) were the most important contributors to the overall aroma of cold‐pressed peanut oil. 2,3‐Pentanedione (OAV = 5,054, buttery), 2‐methoxy‐4‐vinylphenol (OAV = 326, smoky), 2,5‐dimethylpyrazine (OAV = 160, roasted and nutty) and 2‐methylpyrazine (OAV = 92, roasted and nutty) were the most important contributors among the 26 key odorants to the aroma of roasted peanut oil. Roasting peanut seeds induced apparent changes in the formation of aromatic heterocycles, loss of terpenes and increase in lipid oxidation odorants in peanut oil. This study would provide important practical applications in aroma regulation and process optimisation of peanut oil.

Succession patterns of aroma components during brewing process of broomcorn millet (Panicum miliaceum L.) Huangjiu

The flavor of Huangjiu is closely related to its brewing technology. Patterns of aroma component succession during the process of brewing broomcorn millet Huangjiu were investigated by solvent-assisted flavor evaporation combined with gas chromatography–mass spectrometry and chemometrics. During fermentation, esters, alcohols, acids, ketones, acetals, sulfur compounds, furans, and lactones were formed mostly in the chief fermentation stage; nitrogenous and phenolic compounds increased in the primary fermentation stage and then decreased; aldehydes decreased after fermentation started; and terpenes decreased after five days. During aging, acids, alcohols, ketones, lactones, phenols, and nitrogenous and sulfur compounds first decreased and then increased; and esters, acetals, aldehydes, and furans always increased, while terpenes decreased continuously. Key odorants, including acetic acid, 3-methylbutanoic acid, 1,1-diethoxyethane, and 3-methylbutanal, were produced in large quantities in the primary fermentation stage; ethyl lactate, β-phenylethanol, and 2/3-methyl-1-butanol were generated in large quantities in the chief fermentation stage; and sotolon and methional were generated in the aging stage. This study is of great significance for the quality control of Huangjiu production.

Influence of the ripening chamber’s geographical location on dry-cured Iberian ham’s key odorants

Olfactometric and sensory analyses have been applied to study the possible influence of the ripening chamber’s geographical location on the aroma sensory profiles and key odorants of Iberian ham. Dry-cured Iberian ham was obtained from 3 acorn-fed pigs and, for the first time, both of the participating production facilities, located in two different Andalusian municipalities with different altitudes above mean sea level, processed one of the two hind legs from each pig. The descriptive sensory profile of orthonasal and retronasal odours was determined by trained panellists, while odour-active compounds were determined by gas chromatography/mass spectrometry-olfactometry (GC/MS-O). The results obtained showed that, separately, both techniques enable Iberian ham samples to be differentiated by their ripening chamber’s geographical location. For sensory analysis, retronasal sensory analysis appeared to be the most suitable for this goal, highlighting the “meat broth odour” and “roasted nuts odour” descriptors which presented significant differences between geographical locations for samples from all pigs. Moreover, ripening chamber’s geographical location characteristics and the initial composition of the raw material seemed to influence the content of some odour-active compounds. The odour-active compound identified as octane/acetone and isobutanol were conditioned by the ripening chamber’s geographical location, while decanal/2-ethyl-1-hexanol, 1-undecanol, 2-furanmethanol and cis-2-nonenal were also influenced by the individual pig itself. This study showed that slight climatological differences due to the location of the ripening chamber seem to have somewhat of an influence on the aromatic profile.

Dispersion, olfactory effect, and health risks of VOCs and odors in a rural domestic waste transfer station

The impact of odorous gases emitted from refuse transfer stations has always been a concern raised by the surrounding residents. The emitted volatile organic compounds (VOCs) and odors were investigated in a rural solid waste transfer station (RSWTS) located in Southwest China. A total of 70 VOCs were identified and quantified. The total VOCs (TVOCs) concentrations varied from 848.38 to 31193.24 μg/m3. Inorganic odor and greenhouse gases concentrations ranged from 39.11 to 470.14 μg/m3 and 1.03–525.42 μg/m3, respectively. Oxygenated compounds contributed the most (58.25%) to the VOCs. Among the oxygenated compounds, ketones, esters, and ethers were the dominant categories, accounting for 67.5%, 12.70%, and 11.85%, respectively. The key odorants included propionaldehyde, hexanaldehyde, propionic acid, acetaldehyde, and disopropyl ether. N-nitrosodiethylamine, acrylonitrile, and 1,3-Butadiene were the three main carcinogens that pose considerable risk to human health. Allyl chloride was the most non-carcinogenic pathogen among the VOCs detected in RSWTS. With diffusion in the downwind direction, the concentration of VOCs decreased gradually, and their risks weakened accordingly. At the sampling site of RSWTS-10, located 100 m away from RSWTS, acrylonitrile and 1,3-Butadiene still presented an unacceptable carcinogenic risk to human health. This study provides new data for assessing the emission characteristics, olfactory effects, and health risks of trace VOCs, especially those released from RSWTS.

Production of process flavorings from methionine, thiamine with d-xylose or dextrose by direct extrusion: Physical properties and volatile profiles.

The conventional method to produce process flavoring is non-continuous, time consuming, and generates a high volume of effluent. This research aimed to evaluate the use of methionine, thiamine, and reducing sugars to develop process flavorings by direct extrusion, as a potential alternative to the conventional method. The mixed substrates consisted of methionine: d-xylose (MX), methionine: dextrose (MD), thiamine: d-xylose (TX), and thiamine: dextrose (TD) at 80:20 w/w. Three barrel temperatures of the extruder were controlled at 65, 80, and 50°C, respectively, a screw speed of 30rpm and feed rate at 3 kg/hr. Appearance, pH, odor, and taste description of the product from each mixture were determined. Volatile compounds, possibly occurred from the Maillard reaction during the extrusion were analyzed by gas chromatography-mass spectrometry. The products exhibited different levels of meaty odor and bitter taste. Those obtained from MD showed the highest L* (lightness, 85.37) and frequency for just-about-right in terms of taste (33.33%) and odor (60.00%). Products from MX and MD presented the highest frequency for intense taste, and higher frequency for color compared to TX and TD. More volatile compounds were detected from the use of methionine than from thiamine. The key meaty odor compounds such as dimethyl disulfide, dimethyl trisulfide, methional, and methanethiol were found in the samples from MX and MD, while only dimethyl disulfide was detected in the mixture of TX and TD. Finally, the results demonstrated that direct extrusion reaction from methionine and d-xylose or dextrose is a highly efficient method to produce meaty process flavorings. PRACTICAL APPLICATION: The manuscript describes the production of process flavorings that exhibited meaty flavors by extrusion process. Physical properties, volatile profiles, and sensory evaluation of the products from methionine, thiamine, d-xylose, and glucose were evaluated. The extruded products from methionine and dextrose exhibited acceptable color, taste, and odor and presented many volatiles compounds contributing to meaty flavors. The results revealed the high potential to use a direct extrusion process with very low effluent, compared to the conventional method, to produce meaty flavors for industrial application.

Sensomics-assisted flavor decoding of coarse cereal Huangjiu

Huangjiu is one of China’s national alcoholic beverages. The key odorants in four coarse cereal Huangjius (CCH) were identified by sensomics approach. Eighty-eight odorants were identified using solvent-assisted flavor evaporation combined with gas chromatography–olfactometry/spectrometry and aroma extract dilution analysis. Four aroma recombinates showed good similarities to the corresponding original aroma profiles (93.27–96.97%). Partial least squares regression analysis predicted vanillin and β-damascenone were the main causes of the aroma differences in the four CCHs. For the first time, omission and addition tests showed that β-damascenone caused the sweet and tea leaf aromas, whereas hexanal, nonanal, and 2-methyl-3-(methyldisulfanyl)furan contributed to the cooked grain aroma. Finally, 2-phenylethanol, ethyl (E)-3-phenyl-2-propenoate, ethyl 3-phenylpropanoate, vanillin, 3-(methylsulfanyl)propanal, γ-nonalactone, sotolon, β-damascenone, hexanal, nonanal, and 2-methyl-3-(methyldisulfanyl)furan were confirmed as the key odorants in the CCHs. 2-Methyl-3-(methyldisulfanyl)furan was a newly identified key odorant in Huangjiu.

Sensomics-Assisted Aroma Decoding of Pea Protein Isolates (Pisum sativum L.).

The aroma of pea protein (Pisum sativum L.) was decrypted for knowledge-based flavor optimization of new food products containing pea protein. Sensomics helped to determine several volatiles via ultra-high performance liquid chromatography tandem mass spectrometry and 3-nitrophenylhydrazine derivatization. Among the investigated volatiles, representatives of aldehydes, ketones, and acids were reported in literature as especially important in pea and pea-related matrices. After validation of the method and quantitation of the corresponding analytes, sensory reconstitution as well as omission studies of a selected pea protein were performed and revealed nine odor-active compounds as key food odorants (3-methylbutanal, hexanal, acetaldehyde, (E,E)-2,4-nonadienal, (E)-2-octenal, benzaldehyde, heptanal, 2-methylbutanal, and nonanoic acid). Interestingly, eight out of nine compounds belonged to the chemical class of aldehydes. Statistical heatmap and cluster analysis of all odor activity values of different pea proteins confirmed the obtained sensory results and generalize these nine key food odorants in other pea proteins. The knowledge of key components gained shows potential for simplifying industrial flavor optimization of pea protein-based food.

Identification of the influential odorants for the unpleasant rancid smell of ripe noni fruit (Morinda citrifolia)

SummaryIn this study, the volatile changes of noni fruit in various ripening stages were analysed using gas chromatography–mass spectrometry. Eleven of the 35 identified volatiles were found odour‐active through gas chromatography–olfactometry. Based on the aroma extract dilution analysis, hexanoic acid, octanoic acid and their methyl esters were considered as the key odorants for the smell of noni fruit. Results also indicated that the sensory perception of the rancid smell was resulted from the antagonistic effects of the key acid and methyl ester odorants. This study may facilitate the improvement of the acceptability of noni processed foods in the future.

Comprehensive Evaluation of the Volatomic Fingerprint of Saffron from Campania towards Its Authenticity and Quality.

The volatile profiles of eight saffron samples (seven cultivated and one spontaneous) grown in different geographical districts within the Campania region (southern Italy) were compared. Using headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC-MS), overall, 80 volatiles were identified in the eight landraces. Among them, safranal and its isomers and other related compounds such as isophorones, which are not only key odorants but also pharmacologically active metabolites, have been detected in all the investigated samples. Principal Component Analysis performed on the volatiles’ compounds revealed that the spontaneous sample turned out to be an outlier. In particular, the volatile organic compounds (VOCs) profile of the spontaneous saffron presented four lilac aldehydes and four lilac alcohol isomers, which, to the authors’ knowledge, have never been identified in the volatile signature of this spice. The multivariate statistical analysis allowed the discrimination of the seven cultivate saffron ecotypes in four well-separated clusters according to variety. Moreover, 20 VOCs, able to differentiate the clusters in terms of single volatile metabolite, were discovered. Altogether, these results could contribute to identifying possible volatile signature metabolites (biomarkers) or patterns that discriminate saffron samples grown in Campania region on a molecular basis, encouraging future biodiversity programs to preserve saffron landraces revealing valuable genetic resources.

Changes in key aroma-active compounds and sensory characteristics of sunflower oils induced by seed roasting.

This study investigated the changes in aroma composition and perception of sunflower oils induced by seed roasting using sensory-oriented flavor analysis. Volatile compounds were extracted by solvent-assisted flavor evaporation and headspace solid-phase microextraction. Odorants were characterized by gas chromatography-olfactometry-mass spectrometry and aroma extract dilution analysis. The cold-pressed and roasted sunflower oils contained 13 and 50 odorants, respectively, with the flavor dilution factors between 1 and 256. Fifty-six odorants were newly identified in sunflower oils. Quantification of 26 important odorants by the external standard method revealed apparent changes induced by seed roasting in loss of terpenes, formation of Maillard reaction products, and the increase in lipid oxidation products. The most important odorants (odor active values, OAVs=1-1857) in the cold-pressed sunflower oil included α-pinene (11,145µg/kg), β-pinene (4068µg/kg), linalool (56µg/kg), hexanal (541µg/kg), octanal (125µg/kg), α-phellandrene (36µg/kg), and (E)-2-octenal (69µg/kg), contributing to the raw sunflower seed, woody, green, earthy, and sweet aromas of the oil. The most important contributors (OAVs=1-884) to the roasted, smoky, and burnt aromas of the roasted sunflower oil were 2- and 3-methylbutanal (6726 and 714µg/kg), 2,6-dimethylpyrazine (2329µg/kg), 2,5-dimethylpyrazine (12,228µg/kg), 2,3-dimethylpyrazine (238µg/kg), 2,3-pentanedione (1456µg/kg), 2-pentylfuran (1332µg/kg), 2,3-dimethyl-5-ethylpyrazine (213µg/kg), and 1-pentanol (693µg/kg). Aroma recombination of the key odorants in odorless sunflower oil adequately mimicked the general aroma profiles of sunflower oils. This study provides an important foundation for understanding the relationship between oil processing and aroma molecules of sunflower oils. PRACTICAL APPLICATION: The clear changes observed in the composition and concentrations of key aroma compounds explained the changes in sensory characteristics of sunflower seed oils induced by seed roasting on a molecular basis. Characterizing the key aroma-active composition of sunflower oil and investigating its relationship with oil processing could provide important practical applications for the sunflower oil industry in flavor regulation, quality control, product development, and process optimization.

Dynamic release and perception of key odorants in grilled eel during chewing

The release mechanism of odorants in the oral cavity during consumption directly affects sensory attributes, consumers’ preferences, and ultimately purchase intent. Targets was set to monitor in real-time the key odorants released from grilled eel during mastication via an atmospheric pressure chemical ionization mass spectrometry (APCI-MS) connected with a nose interface. The release and perception of odorants during mastication were divided into three distinct phases. Dimethyl sulfide was the main odorant in the first stage. The release and perception of fishy aromas were predominant in the middle and last stages of mastication contributed by trimethylamine, 1-penten-3-ol, and 2-methyl-1-butanol. Chewing behavior experiments suggested that extending the chewing period to >20 s and having a chewing frequency of 2 cycles/s could enhance the aroma delivery of grilled eel and optimize the consumer experience. Consequently, the results explained the relationship between aroma release and the optimal chewing behavior for grilled eel consumption.

Development of Profiling Methods for Contraband Firearm Volatile Odor Signatures

The early detection and location of firearm threats is critical to the success of any law enforcement operation to prevent a mass shooting event or illegal transport of weapons. Prevention tactics such as firearm detection canines have been at the front line of security tools to combat this national security threat. Firearm detection canines go through rigorous training regimens to achieve reliability in the detection of firearms as their target odor source. Currently, there is no scientific foundation as to the chemical odor signature emitted from the actual firearm device that could aid in increased and more efficient canine training and performance protocols or a better understanding of the chemistry of firearm-related odorants for better source identification. This study provides a novel method application of solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) as a rapid system for the evaluation of odor profiles from firearm devices (loaded and unloaded). Samples included magazines (n = 30) and firearms (n = 15) acquired from the local law enforcement shooting range. Headspace analysis depicted five frequently occurring compounds across sample matrices including aldehydes such as nonanal, decanal, octanal and hydrocarbons tetradecane and tridecane. Statistical analysis via principal component analysis (PCA) highlighted a preliminary clustering differentiating unloaded firearms from both loaded/unloaded magazines and loaded firearm devices. These results highlight potential odor signature differences associated with different firearm components. The understanding of key odorants above a firearm will have an impact on national security efforts, thereby enhancing training regimens to better prepare canine teams for current threats in our communities.

The Chemistry of Agarwood Odorants.

The phytochemistry of the fragrant infected heartwood of Aquilaria and Gyrinops species, agarwood (oud), is critically reviewed, highlighting the use of this remarkable natural raw material in perfumery. The chemistry of the two main groups of constituents of agarwood (sesquiterpenoids and chromones) is discussed, focusing particularly on the former structural type. The identities of the main key odorants of agarwood essential oil and of the smoke produced by heating the wood of agarwood are also discussed.

Characterization of Key Odorants in Xinyang Maojian Green Tea and Their Changes During the Manufacturing Process.

Xinyang Maojian (XYMJ) green tea is a famous high-grade Chinese green tea, but the key odorants contributing to its aroma have been poorly understood. In this study, solid-phase microextraction and solvent-assisted flavor evaporation were used for sample preparation, and gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used for both qualitative and quantitative analysis. A total of 50 volatile compounds of five chemical classes were identified in XYMJ tea infusion. Among them, nine odorants including nonanal, β-ionone, octanal, E-nerolidol, linalool, cis-3-hexenyl hexanoate, geraniol, decanal, and β-cyclocitral were identified as key odorants of XYMJ based on GC-O, odor activity values, and aroma combination experiments. Changes in the content of these aroma-active compounds during the manufacturing process of XYMJ (fresh leaves, fixing, rolling, shaping, and drying) were also determined. Most aroma-active compounds decreased after the fixation process, with the exception of cis-3-hexenyl hexanoate. This is the first study to investigate the key odorants in XYMJ using the sensomics approach. The findings of this study provide novel information on the aroma quality of XYMJ.

Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage.

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.