Aroma-active Compounds Research Articles

The volatile composition, aroma profile and antioxidant capacity of Yijiangzi (Aatragalus sinicus L.) monofloral honey and its correlation with the flower

Yijiangzi honey is a well-known monofloral honey in China and also known as Chinese milk vetch (Aatragalus sinicus L.) honey (CMVH). In this study, GC-IMS and GC-O-MS methods were employed to identify the volatile and aroma active compounds of the CMVH and the flower (CMVF). For GC-IMS analysis, 23 of 27 detected volatiles in the CMVH could be observed in the CMVF, indicating that most of the volatiles might be derived directly from the flower. For GC-O-MS, 6 volatiles were identified as aroma-active compounds of CMVH due to their high odor activity values (OAVs), and ethyl 3-phenylpropionate was identified in the honey for the first time. Moreover, the CMVH and CMVF revealed efficient antioxidant capacities that might attribute to the relatively high contained total flavonoids contents (TFC) and total phenolic contents (TPC). The obtained results would be conducive to better understanding of the aroma profile and bioactivity of CMVH.

Effects of Fermentation with Eurotium cristatum on Sensory Properties and Flavor Compounds of Mulberry Leaf Tea.

Mulberry leaf tea (MT) is a popular Chinese food with nutrition and medicinal functions. Solid-state fermentation with Eurotium cristatum of MT (FMT) can improve their quality. Differences in chromaticity, taste properties, and flavor characteristics were analyzed to evaluate the improvements of the sensory quality of FMT. After fermentation, the color of the tea infusion changed. The E-tongue evaluation results showed a significant decrease in unpleasant taste properties such as sourness, bitterness, astringency, and aftertaste-bitterness, while umami and saltiness taste properties were enhanced post-fermentation. Aroma-active compounds in MT and FMT were identified and characterized. A total of 25 key aroma-active compounds were screened in MT, and 2-pentylfuran showed the highest relative odor activity value (ROAV). A total of 26 key aroma-active compounds were identified in FMT, and the newly formed compound 1-octen-3-one showed the highest ROAV, which contributed to FMT's unique mushroom, herbal, and earthy flavor attributes. 1-octen-3-one, (E)-2-nonenal, trimethyl-pyrazine, 2-pentylfuran, and heptanal were screened as the potential markers that contributed to flavor differences between MT and FMT. E. cristatum fermentation significantly altered the sensory properties and flavor compounds of MT. This study provides valuable insights into the sensory qualities of MT and FMT, offering a theoretical basis for the development of FMT products.

A comparative study to determine the key aroma components of yogurt aroma types based on Sensomics and Flavoromics

This study used Sensomics to examine four previously obtained yogurt aroma type profiles. 14 key aroma-active compounds were identified as significant contributors (p ≤ 0.05) in the four aroma types using gas chromatography–mass spectrometry-olfactometry (GC–MS/O), aroma extract dilution analysis (AEDA), odor activity values (OAV), and aroma recombination and omission experiments. The Sensomics and previous Flavoromics results were compared, showing that Flavoromics identified 10 indicator compounds for distinguishing aroma types. Eight were the same as the key aroma-active compounds identified via Sensomics, namely acetic acid, pentanoic acid, decanoic acid, 3-hydroxy-2-butanone, 2,3-pentanedione, acetaldehyde, δ-decalactone, and dimethyl sulfone. Sensomics revealed a prominent similarity between the categories of key aroma-active compounds of the four aroma types, with a higher sensory contribution. Flavoromics showed less overlapping between the indicator compounds, mainly related to the distinction between the four aroma types. Sensomics and Flavoromics serve distinct research objectives and should be selected according to the study subject.

Characterization of aroma and aroma-active compounds of black carrot (Daucus carota L. ssp. sativus var. atrorubens Alef.) pomace by aroma extract dilution analysis

The aim of this study was to characterize the aroma and aroma-active compounds of black carrot pomace, a valuable by-product of black carrot juice industry. Aroma compounds were analyzed using GC-MS-O and extracted via the SAFE technique. The extract samples were determined to represent the odor of black carrot pomace quite well according to the results of the representative test. Accordingly, the aromatic extract scored 77.7 mm for intensity and 87 mm for similarity on a 100 mm unstructured scale. A total of 47 volatile constituents were identified and quantified including terpenes (20), alcohols (11), acids (7), esters (4), ketones (4), and lactone (1). It was observed that terpenes were the major aroma group. The use of aroma extract dilution analysis (AEDA) revealed only 29 of these compounds as aroma-active constituents. Phenylethyl alcohol (FD:512, OAV: 2488, rose) and phenylethyl acetate (FD:256, OAV:280, rose) were the aroma substances providing the strongest rose odor. Following these compounds, acetic acid (vinegar), dimethyl-propanedioic acid (pungent), (E)-β-caryophyllene (salty cheese) and elemicin (spicy) were identified as other strong aroma-actives with FD values of 128 contributing to the characteristic odor of the black carrot pomace samples. The odor activity values (OAVs) ranged from 1 to 2488. The highest OAVs represent the high aromatic active compounds (FD ≥ 128). The distinctive aroma and rich color of black carrot pomace make it a recommended choice for enhancing flavor and adding natural coloring to food products.

Influences of thioalcohols on the release of aromas in sesame-flavor baijiu

This study investigated the interactions between 2-furylmethanethiol, benzenemethanethiol, and 18 skeletal aroma-active compounds as well as four aroma notes in sesame-flavor baijiu based on the Feller Additive Model, the Odor Activity Value (OAV) Approach, and the Sigma-Tau (σ-τ) plots. In addition, a predictive model for the interactions between 2-furylmethanethiol and esters was developed, and the determinants of the interaction results in complex systems were explored. The results reveal that both thioalcohols interacted with the skeletal aroma-active compounds in a similar trend, where 2-furylmethanethiol tends to enhance the release of fruit and acid aroma. Moreover, the intensity of the thiols and their intensity ratio to the notes were the determinants of the interaction results in the multivariate blended system, with the lower the concentration of the thiols, the closer the ratio was to 1, and the more likely that additive interactions would take place. Predictive modeling showed that 2-furylmethanethiols were more likely to have additive or synergistic effects with esters when the olfactory thresholds of the esters were between 75.86 and 199.53 μg/L. Conversely, masking effects were more likely.

Insights into the flavor endowment of aroma-active compounds in cloves (Syzygium aromaticum) to stewed beef

Clove (Syzygium aromaticum) is one of the most commonly used spices in stewed beef to enrich and improve its aroma during the stewing process. Gas chromatography ion mobility spectroscopy (GC-IMS), Q Exactive GC-Orbitrap-MS-O (QE-GC–MS/O), combined with sensory evaluation were employed to analyze the flavor endowment of aroma-active compounds in cloves to stewed beef. A total of 173 volatiles were identified in the clove powder (CP), stewed beef with clove (SBC), and stewed beef with salt (SBS), of which 21 volatiles were considered as aroma-active compounds. The concept of flavor endowment of aroma-active compounds in cloves was defined innovatively, and the endowment rate values (ERVs) of stewed beef were calculated. Nine aroma-active compounds in cloves were found to have a flavor endowment effect on stewed beef, while the terpenoids exhibited high ERVs. Despite the low ERV of eugenol, it still significantly impacted the aroma profile of SBC due to its high odor activity value (OAV) and flavor dilution (FD) factor. These volatiles offered mainly the clove, herbal, anise, and floral odor to stewed beef, which was also confirmed by sensory evaluation. These findings indicated that the terpenoids, phenolics and ethers in cloves had a significant influence on the overall aroma of stewed beef through the flavor endowment, which contributed to the precise use of cloves and improved the aroma of stewed beef.

Comparative analysis of the aromatic profile of single malt whiskies from different regions of Scotland using GC-MS, GC-O-MS and sensory evaluation

Single malt whiskies are popular around the world. The 37 esters, 10 alcohols, 10 phenols, 8 aldehydes, 8 acids, 6 alkanes, 4 ketones and 3 heterocycles were detected in the single malt whiskies extracted from different origins in Scotland by HS-SPME (headspace solid-phase microextraction) and LLE (liquid-liquid extraction) and identified by GC-MS (gas chromatography-mass spectrometry). QDA (quantitative descriptive analysis) combined with multivariate statistics were used to investigate the effects of the differential aroma-active compounds on the sensory aroma characteristics. O-cresol, ethyl 2-methylbutyrate, 5-methylfurfural and propionic acid might influence the flavor of single malt whiskies of different origins in Scotland. The 54 key whisky aroma compounds were analyzed, with isoamyl acetate having the highest OAV (odour activity value) of all whisky samples. In addition, the aromas of volatile compounds were analyzed using OSME (odor-specific magnitude estimation) and OAV. Based on these facts, the researchers developed a flavour wheel with 10 aroma profiles. This paper evaluates Scotch single malt whisky from a Chinese perspective, which helps the development of the Chinese whisky market.

Comparative characterization of volatile organic compounds and aroma profiles in 10 Actinidia arguta cultivars by gas chromatography-mass spectrometry (GC–MS), sensory analysis, and odor activity value (OAV) combined with chemometrics

Actinidia arguta, a widely consumed fruit, is well-known for its distinct flavor. However, there has been a lack of systematic investigation on the differences in volatile organic compounds (VOCs) and aroma characteristics among cultivars. In this study, 10 A. arguta cultivars were analyzed for aroma characteristics by GC–MS, sensory analysis, and OAV combined with chemometrics. A total of 52 VOCs were identified, with terpenoids being the most abundant. Based on partial least squares-discriminant analysis (PLS-DA), 12 VOCs were identified as biomarkers for distinguishing cultivars. Furthermore, 28 VOCs were found as aroma-active compounds, contributing fruity, green, floral, sweet, and minty aroma notes to A. arguta. Notably, α-ionone, β-ionone, and β-damascening exhibited high OAVs, making a significant contribution to the floral note. An aroma wheel was developed to represent the overall aroma profile of A. arguta. These findings provide a theoretical foundation for quality evaluation and cultivar breeding of A. arguta.

Characterization of key aroma-active compounds in fermented chili pepper (Capsicum frutescens L.) using instrumental and sensory techniques

The aroma profile of fermented chili pepper was analyzed using gas chromatography–mass spectrometry (GC–MS) coupled with chromatography-olfactometry (GC-O). A total of 19 aroma-active compounds were detected, exhibiting aroma intensities spanning from 1.8 to 4.2. And 12 aroma-active compounds were determined as pivotal odorants through odor activity value (OAV) calculation. Concentrations of these aroma-active compounds were quantified and subsequently employed in reconstructing the aroma profile of fermented chili pepper. Quantitative descriptive sensory analysis and electronic nose analysis proved that the aroma profile of fermented chili pepper was basically reconstituted. Omission experiments confirmed that methyl salicylate, linalool, 2-methoxy-3-isobutylpyrazine, and phenylethyl alcohol were the key aroma-active compounds of fermented chili pepper. Moreover, the perceptual interactions between the key aroma-active compounds were investigated. It was found that methyl salicylate masked the floral aroma, while phenylethyl alcohol had an additive effect on the aroma of linalool and 2-methoxy-3-isobutylpyrazine.

Characterization of the key odorants in Amomum tsao-ko cobs by sensory directed flavor analysis

To decode the key odorants in Amomum tsao-ko cobs (ATC) and to examine the impact of extraction methods on key odorants, volatiles of ATC were isolated by both hydrodistillation (HD) and solvent extraction combined with solvent-assisted flavor evaporation (SE-SAFE). In total, 49 aroma-active compounds with flavor dilution (FD) factors between 1 and 8192 were detected by gas chromatography–olfactometry-mass spectrometry, of which 39 and 42 odorants were identified in the HD and SAFE extracts, respectively. The 34 odorants (FD ≥ 16) were further quantitated; odor activity value calculations, aroma reconstitution and omission experiments were conducted to evaluate their contributions to the characteristic odor of ATC, and 11 compounds were confirmed as key odorants of ATC. Furthermore, the majority of the potent odor-active compounds in the two extracts were identical, but their concentrations were significantly different. The outcomes will give a theoretical foundation for developing and utilizing ATC.

Effect of storage time on aroma profiles of wuyi rock tea

Wuyi rock tea (WRT) is typically stored for weeks or months before consumption, and the roasted aroma changes into a floral aroma during the storage. However, little is known about the aroma change that occur during this period. The aroma in WRT during storage was extracted and identified using simultaneous distillation extraction coupled with gas chromatography mass spectrometry, in addition to calculating the odor activity value (OAV) and conducting aroma recombination experiments. The results revealed the emergence of floral aroma with increasing storage time. Alcohols, aldehydes, and aromatics were the main volatile types in WRT. According to partial least squares discriminant analysis, 20 volatiles were crucial variables contributing to the volatile differences in WRT with variations in storage time. The key volatiles causative for the overall aroma of WRT were determined based on their OAVs. In total, 25 volatiles with OAVs >1 were identified as aroma-active compounds. Notably, trans-β-ionone, 2-ethyl-3,5-dimethylpyrazine, linalool, octanal, nonanal, dehydro-β-ionone, and pentylfuran were substantial players in the overall aroma profile of WRT under storage. Based on the results of aroma combination experiments, the contribution of 18 volatiles with OAVs >2 to the overall aroma of WRT was confirmed. The findings augment our comprehension of aroma development in WRT throughout the storage.

Unraveling chemical changes associated with the sensory quality of Chinese steamed bread as altered by wheat flour type

Chinese steamed bread (CSB) is an important staple of the Chinese people, and its flavor profile is mostly affected by wheat varieties among others. This study selected wheat flour made from three different wheat varieties and investigated their contribution to the CSB flavor profile in terms of metabolism. Thirteen aroma-active compounds identified by GC-O were determined as the main contributors to the different aroma profiles of three CSBs. 350 sensory trait-related metabolites were obtained from five key modules via weighted gene co-expression network analysis. It was found that the sensory characteristics of CSBs made of different wheat flour were significantly different. The higher abundance of lipids in Yongliang No.4 (YL04) wheat flour was converted to large number of fatty acids in fermented dough, which led to the bitterness of CSB. Besides, the abundance in organic acids and fatty acids contributed to the sour, milky, wetness and roughness attributes of YL04-CSB. More fatty amides and flavonoids in Jiangsu Red Durum wheat flour contributed to the fermented and winey attributes of CSB. Carbohydrates with higher abundance in Canadian wheat flour was involved in sugar-amine reaction and glucose conversion, which enhanced the sweetness of CSB. In addition, fatty acids, organic acids, amino acids, and glucose were crucial metabolites which can further formed into various characteristic compounds such as hexanal, hexanol, 2,3-butanediol, acetoin, and 2,3-butanedione and thus contributed to the winey, fresh sweet, and green aroma properties. This study is conductive to better understand the evolution of the compounds that affect the quality and aroma of CSBs.

Exploring microbial and moist-heat effects on Pu-erh tea volatiles and understanding the methoxybenzene formation mechanism using molecular sensory science

Piling fermentation (PF) is crucial for Pu-erh tea aroma, yet its microbial and moist-heat impact on aroma quality is poorly understood. Solid-phase microextraction, solvent-assisted flavor evaporation, and gas chromatography–mass spectrometry were used to detected and analyses the samples of sun-green green tea, sterile PF and spontaneous PF. Microbiological action promotes the formation of stale aromas. Moist-heat action promotes the formation of plum-fragrance and sweet aroma. 20 microbial markers and 28 moist-heat markers were screened from 184 volatile components. Combining odor activity values and gas chromatography-olfactometry, 22 aroma-active compounds were screened (1,2,3-trimethoxybenzene, linalool, 1,2,4-trimethoxybenzene …), and analyzed during PF processing. Aroma omission and addition experiments verified its importance. Gallic acid addition experiments successfully verified that microorganisms are the main contributors to the synthesis of methoxybenzenes. Finally, Blastobotrys, Rasamsonia, and Thermomyces showed positive correlation with the synthesis of 1-ethyl-4-methoxybenzene, 1,2,4-trimethoxybenzene, 1,2,3-trimethoxybenzene, and 1,2-dimethoxybenzene. The formation mechanism of Pu-erh tea's aroma was clarified.Exploring microbial and moist-heat effects on Pu-erh tea volatiles and understanding the methoxybenzene formation mechanism using molecular sensory science.

Characterization of aroma profiles in flat peach juice post-thermal sterilization: Insights from comprehensive two-dimensional GC with time-of-flight mass spectrometry (GC×GC-TOF-MS), sensory analysis, and chemometric approaches

In this study, three thermal sterilization samples, namely pasteurization (PS), high-temperature short-time treatment (HTST) and thermal ultrasonic sterilization (TS) were employed to assess their impact on the flavor profile of flat peach juice through instrument detection and sensory analysis. Results showed significant differences in the sensory profiles among various thermal-sterilized samples, accompanied by diverse levels of reduction in volatile compounds. Totally, 175 volatile compounds were identified through the combination of GC-MS and GC×GC-TOF-MS analyses. Among these, 26 compounds were recognized as aroma-active compounds, displaying high relative odor activity values (rOAVs). Moreover, 5 sulfur-containing compounds were identified for the first time in the sterilized samples. Partial least-squares regression (PLSR) revealed a positive correlation between acetaldehyde, β-damascenone, (E)-2-octenal, and 1-octen-3-ol with off-odors and cooked attributes. This study offers crucial theoretical foundations for refining the processing technology of flat peach juice, thus facilitating the optimization of sensory attributes in juice products through the regulation of pertinent parameters.

Characterisation of aroma-active compounds in dried Dendrobium spp. stems (Shihu) using GC-Olfactometry and a modified NIF-SNIF method

Dendrobium orchid stems (Chinese name Shihu) are becoming popular ingredients in food and drinks such as wine, teas and desserts, however, its aroma chemistry is not currently understood. Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O) were used to analyse two Dendrobium species. The Nasal Impact Frequency-Surface of Nasal Impact Frequency (NIF-SNIF) method was employed on thirteen untrained panellists using a newly built open-source software (“nif-simple”). An expert annotated odour descriptions and intensities of NIF-SNIF peaks. Twenty-four volatile aroma compounds were found using GC-MS, with 22 shared compounds and 17 reported for the first time. GC-O NIF-SNIF indicated nine aroma compounds were aroma-active in D. nobile and D. officinale. Five were found in both species suggesting that they are species-independent markers. Aroma-active compounds were characterised as brown, mushroom, metallic, nutty and potato aromas. Methional (NIF 83 %) and 1-octen-3-one (NIF 81 %) were most frequently detected in D. nobile and D. officinale respectively, and this study proposed aroma formation mechanisms in dried Dendrobium stems. Modified Frequencies demonstrated that NIF-SNIF is an effective GC-O method for identifying key aroma-active compounds. Understanding the flavour properties of Shihu could enhance its global appeal and encourage NIF-SNIF to be used in future studies.

2- Acetyl-1-pyrroline originated from Maillard reaction is the key odorant of cooked Lipu taro

Lipu taro is one of the most famous varieties of taro in China with strong aroma. In this study, vacuum simultaneous steam distillation and extraction and gas chromatography-mass spectrometry were applied to extract and analyze the volatile components, combined with gas chromatography-olfactometry, aroma extraction dilution analysis, odor activity value, aroma recombination and omission experiments to determine the key aroma-active compounds in cooked Lipu taro. Results revealed that 18 odorants, such as 2-acetyl-1-pyrroline (2-AP), (E,E)-2,4-decadienal, methional, nonanal, 1-octen-3-one, etc., were identified as the key aroma-active compounds, and they could recombine the taro aroma at detected concentration. Among these key odorants, 2-AP exhibited the most significant roles in cooked Lipu taro. 2-AP was confirmed to be originated from Maillard reaction, as the addition of Maillard reaction precursors (L-proline and D-glucose) could increase its content significantly. This result offers a practical method of enhancing the characteristic aroma of cooked taro.

Exploring changes in key aroma-active compounds of soy sauce due to different fermentation processes

In this study, two extraction methods combined with gas chromatography-olfactometry-mass spectrometry (GC×GC-O-MS) were used to investigate the sensory characteristics of high-salt dilute fermented soy sauce (HDFSS), and molecular sensory methods were used to characterize its aroma. Among them, 3-methylthiopropanal had the highest odor activity value (OAV) in HDFSS, and acetic acid had the highest content in HDFSS. The results showed that the concentrations of benzyl alcohol, phenethyl alcohol, 1-octen-3-ol, maltol, and 1-hydroxy-2-propanone did not vary significantly in the HDFSS of different fermentation processes. The Y2 HDFSS produced in the koji-making fermentation system 2 had higher concentrations of 3-methyl-1-butanol (malt) and 3-methylthiopropanal (roasted potato). Additionally, it received high aroma scores in the sensory evaluation. Finally, by conducting aroma reconstitution and omission experiments on HDFSS from two different fermentation processes, the key aroma-active compounds, such as phenethyl alcohol, maltol, and guaiacol, were identified.

Characteristic aroma compounds during the fermentation of Chinese steamed bread fermented with different starters

The characteristic aroma compounds of Chinese steamed bread (CSB) fermented with different starters were studied using HS-SPME-GC/MS, aroma recombination and omission experiments. The dynamic changes of the microbiota and their function and metabolites during fermentation were analyzed using metagenomics and non-targeted metabolomics. Forty-nine volatile flavor compounds were identified, while 5 characteristic aroma-active compounds were investigated in CSB fermented with commercial dry yeast (AQ-CSB), and 10 were investigated in CSB fermented with traditional starter (NY-CSB). Microbial structure and function analysis showed that Saccharomyces cerevisiae dominated during AQ-CSB fermentation and contributed >95% to its KEGG pathways, while Pediococcus pentosaceus, unclassified Pediococcus, Lactobacillus plantarum, Lactobacillus brevis and unclassified Lactobacillus were predominant in NY-CSB and together had an ~96% contribution to these pathways. NY-CSB showed higher metabolic activity during fermentation, and the characteristic metabolites were mainly involved in carbohydrate, amino acid and lipid metabolism. The characteristic aroma compounds were identified and increased the understanding of the contributions of the microbiota. This may be useful for designing starter cultures that produce CSB with desirable aroma properties.

Characterization of key aroma-active compounds in fresh and vacuum freeze-drying mulberry by molecular sensory science methods

Mulberry is prone to rapid deterioration, but its quality can be maintained through vacuum freeze-drying. In this study, the aroma compositions of fresh mulberry (FM) and vacuum freeze-dried mulberry (VFDM) were analyzed through headspace solid-phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) coupled with GC×GC–O–TOF-MS. A total of 232 volatiles were detected in FM and VFDM, and the content of volatile compounds in VFDM decreased by at least 21.37 % after drying compared to FM. Additionally, 51 and 50 aroma-active compounds were detected in FM and VFDM, respectively, with 13 aroma-active compounds being identified in FM initially. Based on the aroma extraction dilution analysis (AEDA) results, 14 compounds with high flavor dilution (FD) factors were accurately quantified by GC–MS. The calculated odor activity value (OAV) showed that a total of 12 compounds significantly contributed to the aroma of mulberry. Finally, aroma recombination and omission experimental results showed that (E,Z)-2,6-nonadienal, β-ionone, hexanal, and (E)-2-nonenal were the key aroma-active compounds in FM, whereas (E,Z)-2,6-nonadienal, β-ionone, (E)-2-nonenal, eugenol and ethyl isovalerate were the key aroma-active compounds in VFDM.

Identification of aroma-active compounds in milk by 2-dimensional gas chromatography-olfactometry-time-of-flight mass spectrometry combined with check-all-that-apply questions

Understanding consumers' sensory preferences for dairy products is essential. This study employed sensory analysis and instrumental techniques to analyze the flavor of pasteurized milk and UHT milk. There were 6 milk samples with similar fat content (4.0-4.6 g/100 mL) and protein content (3.2-3.8 g/100 mL). Sensory data from consumer tests was collected using check-all-that-apply (n = 100) and 9-point hedonic preferences. Research showed that Chinese consumers could distinguish the flavor of the 2 types of milk, and UHT milk showed a higher preference score, which may be due to the more pronounced milky flavor and sweet taste of UHT milk. A total of 48 aroma-active compounds were sniffed through 2-dimensional gas chromatography olfactometry time-of-flight MS, among which 11 were determined as key aroma-active compounds. Correlation analysis showed that milky odor, sweetness, and aftertaste-milky were positively correlated with γ-dodecalactone and γ-nonanolactone. Cooked and oxidized taste were positively correlated with 1-octen-3-ol and E-2-octenal. This study is important for developing Chinese dairy products and exporting dairy products to China by multinational companies.