Mass Spectrometry Olfactometry Research Articles

Characterization of key aroma-active compounds in Zanthoxylum schinifolium by sensory evaluation and multiple instrumental analyses

The aroma characteristics of Zanthoxylum schinifolium from four different production areas in Sichuan were identified and compared. Aroma components were analyzed via sensory evaluation, gas chromatography–olfactometry–mass spectrometry (GC–O–MS), and comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (GC × GC–O–MS). The results revealed that minty, spicy, woody, fresh, citrus, and herbal notes could be perceived, with the Jinyang sample exhibiting the most significant aroma profile. Compared with GC–O–MS, GC × GC–O–MS offers advantages in identifying aroma-active compounds, and it can identify more types and quantities of aroma-active compounds. In this study, 40 aroma-active compounds from seven different classes were identified via GC × GC–O–MS. Through aroma extraction dilution analysis (AEDA), 14 aroma-active compounds were quantitatively analyzed, and odor activity values (OAVs) were calculated. Additionally, orthogonal partial least squares discriminant analysis (OPLS-DA) was employed to identify four aroma-active compounds with variable importance in projection (VIP) scores greater than 1, indicating their potential as identification markers. This study enhances our understanding of the sensory characteristics and aroma-active compounds of Zanthoxylum schinifolium.

Impact of Different Wood Types on the Chemical Composition and Sensory Profile of Aged Tsipouro: A Comparative Study

The production of high-quality aged marc spirits includes a minimum period of six months of ageing in oak barrels. Lastly, producers are interested in alternative botanical origin wood. The present study is aimed at investigating the influence of Greek oak (Quercus trojana) and Greek chestnut (Castanea sativa) compared with French (Quercus petraia) and American oak (Quercus alba) on the chemical composition and sensorial characteristics of aged tsipouro, produced from marc from the Black Muscat variety. Gas chromatography–olfactometry–mass spectrometry (GC–O–MS) was used to identify volatile compounds of the aged tsipouro. Also, colour and polyphenol measurements were made, and an organoleptic evaluation was performed by 16 trained tasters. The findings revealed rather similar results between the tsipouro made from different wood species, especially between Greek and French oaks, and relative differentiation for that of chestnut. All the aged distillates exhibited a pleasant and rich aromatic potential, dominated by floral and fruity terpene varietal aromas as well as wood-related volatiles. Chestnut, with a high phenolic potential, gives pleasant organoleptic effects over time and can be an alternative wood for ageing spirits. This research highlights the importance of wood selection in the tsipouro ageing process and enables the use of Greek wood species in the ageing of spirits.

Comprehensive foodomics analysis reveals key lipids affect aroma generation in beef

Lipids are vital precursors to beef aroma compounds, but the exact lipid molecules influencing aroma generation remain unconfirmed. This study employs gas chromatography–olfactometry–mass spectrometry and absolute quantitative lipidomics to identify beef's aroma and lipid profiles and to examine lipid alterations post-thermal processing. The aim is to understand the role of lipids in aroma generation during beef's raw-to-cooked transition. Eighteen key aroma compounds were identified as significant contributors to the aroma of beef. 265 lipid molecules were quantified accurately, and we found that triglycerides containing C18:1 or C18:2 chains, such as TG(16:0_18:1_18:1), TG(16:0_18:1_18:2), TG(16:0_16:1_18:1), as well as phosphatidylcholine and phosphatidylethanolamine containing PC(16:1e_20:4), PC(16:0e_20:4), PC(18:2e_18:2), and PE(16:1e_20:4), played important roles in the generation of key aroma compounds in beef. C18:1, C18:2, C18:3, and C20:4 were key substrates for the formation of aroma compounds. In addition, lysophosphatidylcholine and lysophosphatidylethanolamine containing unsaturated fatty acid chains may serve as important aroma retainers.

Characterization of the Key Aroma Compounds of Soybean Flavor in Fermented Soybeans with Bacillus subtilis BJ3-2 by Gene Knockout, Gas Chromatography–Olfactometry–Mass Spectrometry, and Aroma Addition Experiments

Characterization of the Key Aroma Compounds of Soybean Flavor in Fermented Soybeans with Bacillus subtilis BJ3-2 by Gene Knockout, Gas Chromatography–Olfactometry–Mass Spectrometry, and Aroma Addition Experiments

Characterisation of aroma‐active compounds in wheat flour by molecular sensory science

SummaryFour different extraction methods were used to extract aroma compounds from flour. It was found that dynamic headspace sampling (DHS) was a better method for extracting aroma‐active compounds in flour. Hexanal, decanal, butanoic acid, 2,3‐pentanedione, 2‐acetyl‐1‐pyrrolinoline, and 3‐octen‐2‐one were found to be the important aroma‐active compounds in flour by olfaction (O) in two‐dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC‐O‐MS). Dynamic headspace dilution analysis (DHDA), odour activity value (OAV), recombination and omission experiment further verified that these compounds can roughly simulate the overall aroma profile of flour. In this study, we determined the aroma‐active compounds in flour by molecular sensory science to improve the sensory preference of flour and enhance the quality of flour aroma, which will provide analytical ideas for future research on flour aroma and improve the production process.

Characterization of odor-active compounds in Liuzhou River snail rice noodles soup by sensory-directed flavor analysis

Liuzhou River snails rice noodles, a special snack of Liuzhou City in the Guangxi Zhuang Autonomous Region, China, possess a unique flavor of spicy, refreshing, fresh, sour, and hot. The present study aimed to characterize the composition of volatile compounds and key odor-active compounds in river snails rice noodles soup (RSRNS) through aroma extract dilution analysis and odor activity value calculation using solid-phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC–O–MS) and gas chromatography–olfactometry–mass spectrometry (GC–O–MS). A total of 71 volatile compounds were identified by GC–O–MS, of which 49 were odor-active. Meanwhile, 125 volatile compounds were identified by GC×GC–O–MS, of which 68 were odor-active. These results indicated that 3-methylbutanal, linalool, 1,8-cineole, myrcene, 2-acetylpyrazine, 4-allylanisole, 2-acetylthiazole, 1-octen-3-ol, hexanal, and eugenol were the main odor-active compounds of RSRNS.

Characterization of the key aroma compounds of wild bitter melon lujiu based on LLE coupled with GC–O–MS and the aroma influence of polysaccharide addition using VASE–GC–MS

Wild bitter melon (Momordica charantia L. Var. Abbreviata Ser; WBM) is widely cultivated in East and Southeast Asia. It is made into lujiu with high-quality strong-flavor baijiu and presents a beautiful golden color and harmonious aroma. Lujiu is a type of alcoholic beverage similar to gin. In this study, the aroma profile of wild bitter melon lujiu (WBML) was determined through sensory evaluation, and important aroma-active compounds were identified through liquid–liquid extraction (LLE) coupled with gas chromatography–olfactometry–mass spectrometry (GC–O–MS) and aroma extraction dilution analysis (AEDA). A total of 42 aroma-active compounds were identified, and 28 of them with FD factor ≥ 3 were quantified. Sixteen compounds were pivotal aroma contributors, among which ethyl hexanoate, ethyl pentanoate, ethyl butanoate, ethyl octanoate, and acetic acid had the highest OAVs. Moreover, WBM-sourced aroma compounds were found in WBML, including dihydroactinidiolide, (E,E)-2,4-nonadienal, β-ionone, etc. The extraction parameters of vacuum-assisted sorbent extraction (VASE) were optimized for the first time to analyze lujiu aroma. The effect of homologous polysaccharide addition to the aroma of WBML was explored with VASE–GC–MS. The greasy off-odor was decreased due to the reduction of ethyl octanoate volatility by polysaccharide addition.

Comparative flavor precursors and volatile compounds of Wenchang chickens fed with copra meal based on GC–O–MS

In the Wenchang chicken (WC) feeding process, copra meal is often added to improve chicken quality. To determine the effect of feeding with copra meal on the flavor formation of WCs, the experimental subjects were fed with 4.5 % and 7.5 % copra meal, and the control group was fed without copra meal. The electronic nose combined with gas chromatography–olfactometry mass spectrometry (GC–O–MS) was used to identify the volatile compounds from the samples. Compared with the control group, the pH of chickens fed copra meal was significantly decreased (P < 0.05) after slaughter. Aldehydes and alcohols were the main volatile compounds in muscle, among which hexanal and 1-octen-3-ol were the highest. Thirty-two and thirty-six compounds were identified in breast muscle and drumstick muscle, respectively. Twelve new volatile compounds were added, including 1-octanol, butanal, 1-heptanol, 3-ethylbenzaldehyde, 2,2-dimethylpentanal, hexanoic acid, 3-heptanone, 2,5-heptanedione, 2-ethylfuran, 2-propylfuran, 2-ethynylpyridine, and 1,2,4,5-tetrazine. The types and contents of volatile compounds in drumstick muscle increased with an increasing proportion of copra meal in the diet. In summary, the addition of copra meal changed the quality of WCs and increased the types and contents of volatile compounds. This study provides a reference for understanding the flavor profile of WC fed copra meal.

Study on the flavor of brown milk fermented by Lactobacillus paracasei K56 in different strain states

A comprehensive investigation of the differences in flavor profiles among different strains of fermented brown milk (FBM) is important to guide the improvement of the flavor quality of FBM. Seven samples were analyzed by dynamic headspace extraction (DHS) and gas chromatography–olfactometry–mass spectrometry (GC–O–MS), and a total of 73 odor compounds were identified. Key odor compounds including 3-methyl-1-butanol, ethyl acetate, linalool, furfuryl alcohol, 2-pentylfuran, hexanal, and 1-octen-3-ol, were screened by multivariate statistical analysis to reveal the flavor differences of FBM from different strains. 3-Methyl-1-butanol and ethyl acetate were found to be the key odor compounds distinguishing FBM by strain K56 from other strains, and the fermentation strains were found to be the key factors affecting the flavor of FBM compared to the fermentation substrate and fermentation process. This study provided a relatively systematic investigation of the flavor of FBM and could be used to monitor changes in odor components and sensory characteristics for product quality control.

Characterization of odor-active compounds in Dahongpao Wuyi Rock Tea (Camellia sinensis) by sensory-directed flavor analysis

Different methods for extraction and analysis of odor-active compounds in Dahongpao (DHP) Wuyi Rock Tea (WRT) were compared. The results showed that two-dimensional gas chromatography–olfactometry–mass spectrometry (GC×GC–O–MS) is a better method than GC–O–MS, stir bar sorptive extraction (SBSE) can extract more odor-active compounds. Aroma extraction dilution analysis (AEDA) and odor activity value (OAV) further indicated that 15 compounds were the most important odor-active compounds in DHP: phenethyl alcohol, (E)-β-ionone, nonanal, linalool, hexanal, geraniol, benzaldehyde, α-ionone, methyl salicylate, 6-methyl-5-hepten-2-one, geranylacetone, benzyl alcohol, tea pyrrole and hexyl hexanoate. The roasting process affected the overall odor characteristics of DHP, and appropriate roasting would enhance the sensory quality of DHP. As the roasting temperature increases, the contribution of compounds such as tea pyrrole, 2-ethyl-6-methylpyrazine, and 2,6-dimethylpyrazine to the roasted and burnt odor of the samples gradually increase, and the concentration of typical floral compounds such as phenethyl alcohol, (E)-β-ionone, α-ionone and linalool increase decidedly under light fire roasting, which was consistent with the sensory evaluation results. This study is helpful to further guide the production process of DHP.

Discovery and Flavor Characterization of High-Grade Markers in Baked Green Tea

Green tea is a popular beverage around the world and possesses a unique flavor. The flavor qualities of green tea are closely related to its grade and this relationship has not yet been studied. Three baked green teas with similar flavor were studied, namely, Huangshan Maofeng, Taiping Houkui, and Shucheng Xiaolanhua. A total of 34 odor compounds were identified by solid phase microextraction (SPME) combined with two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GC×GC-O-MS). The results of the clustering analysis showed that the content of D-limonene and linalool in the high-grade (Grade A) tea was much higher than the content in other grades, so they were identified as odor markers of Grade A baked green tea. The taste components of different grades of green tea infusion were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) and HPLC. A combination of clustering analysis, principal component analysis (PCA), and orthogonal partial least squares discrimination analysis (OPLS-DA) indicated that galloylglucose, digalloylglucose, trigalloyglucose, strictinin, and gallic acid could be used as taste markers of Grade A baked green tea. Therefore, the results in this paper reveal the substances responsible for the odor and taste markers of high-grade baked green tea.

Decoding the evolution of aromatic volatile compounds and key odorants in Suancai (a Chinese traditional fermented vegetable) during fermentation using stir bar sorptive extraction–gas chromatography–olfactometry–mass spectrometry

This study aimed to reveal the evolution of volatile compounds and key odorants in Suancai during two-stage fermentation using stir bar sorptive extraction–gas chromatography–olfactometry–mass spectrometry (SBSE–GC–O/MS). In total, 138 volatile compounds were identified, and 53 aroma-active compounds were detected. The ester composition and alkane and alcohol contents were different in fresh leaf mustard and Suancai in various fermentation stages. During pre-salting, the aroma profile transformed from pungent to salty as the isothiocyanate level decreased. During secondary fermentation, isothiocyanate levels were further reduced, and esters and alcohols with mild aroma were produced, causing the rich and mild aroma of Suancai. Based on the reduced isothiocyanate content and transformed aroma, isothiocyanate may be a key marker for estimating the maturity degree of Suancai. This study provides a theoretical basis for improving the aromatic quality of fermented vegetables.

Characterization of key odor-active compounds in high quality high-salt liquid-state soy sauce

Solid-phase microextraction and liquid–liquid extraction with gas chromatography– olfactometry–mass spectrometry (GC–O–MS) were used to analyze four award-winning high-salt liquid-state soy sauces (HLS). In this study, 110 volatile odor compounds were detected using GC–O–MS. Twenty key odor-active compounds with a flavor dilution factor ≥ 1024 were identified through aroma extract dilution analysis(AEDA), of which 11 compounds had odor activity values > 1; these were methional, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), guaiacol, 4-hydroxy-2(or 5)-methyl-5(or 2)-ethyl-3(2 H)-furanone (HEMF), 1-hydroxy-2-propanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2-ethyl-6-methylpyrazine, 3-methyl-1-butanol, 2,6-dimethylpyrazine, ethyl benzoate, and 4-ethylguaiacol. Sensory evaluation showed that roasted, cooked potato-like, seasoning-like, and smoky odors were the main odor characteristics in the award-winning HLS. Electronic nose analysis indicated that the odor characteristics of the four samples were significantly different and could be distinguished from each other. This study helps to understand and explore the odor characteristics and key odor components of the award-winning HLS.

Synthesis and odor characteristics of N‐substituted pyrrolyl ketones derived from N‐substituted acetylpyrroles and alcohols

AbstractA transition‐metal and ligand free base‐mediated a radical condensation reaction to form N‐substituted pyrrolyl ketones with water as the side product is developed. The transformation is performed with t‐BuOK, and a broad range of N‐substituted acetylpyrroles and alcohols are well tolerated under the optimized conditions. Preliminary studies indicate that the radical anion of the benzylic alcohol is proposed as the key intermediate, which undergoes coupling with the enolate of the acetylpyrrole to form the new CC bond. Subsequently, the corresponding pyrrolyl chalcones are obtained by elimination, and the enone intermediate is reduced to afford N‐substituted pyrrolyl ketones. The odor characteristics of the pyrrolyl ketones obtained were evaluated by gas‐chromatography–mass spectrometry–olfactometry (GC–MS–O). The pyrrolyl ketones present varied characteristic odors, which are usually distinct from those of the corresponding acetylpyrroles and alcohols. Among them, compounds of 3‐cyclopropyl‐1‐(1‐methyl‐1H‐pyrrol‐2‐yl) propan‐1‐one (3c′) and 5,9‐dimethyl‐1‐(1‐methyl‐1H‐pyrrol‐2‐yl) dec‐8‐en‐1‐one (3g′) were not decomposed under high temperature, according to the results of pyrolysis–GC/MS.

Characterization of odor-contributing volatile in Capsicum chinense ‘JT-1’fruits during development and transcriptome analysis of key fruit-aroma formation periods

Chili pepper (Capsicum spp.) is one of the world's most popular vegetables and spices. C. chinense is a widely consumed domesticated pepper species. Most varieties of this species have distinctive fruity aromas, a trait with high commercial value. Studies have shown that branched-chain esters are the main contributors to the fruity aroma; however, the mechanisms of their accumulation and regulation remain elusive. In this work, we conducted gas chromatography–olfactometry–mass spectrometry analysis of C. chinense pepper ‘JT-1’ fruits harvested from 1 to 7 weeks after flowering (WAF). The main odor-contributing volatile of fruity aroma in ‘JT-1’ fruits was 4-methylpentyl 3-methylbutanoate, the concentration of which dramatically increased at 4 WAF. A shift in the dominant volatile organic compound (VOC) profile from aldehydes and alcohols to esters occurred from 3 to 4 WAF. Transcriptome analysis of fruits at these two stages and qPCR results revealed that the up-regulating of CcBcat4 may play an essential role in accumulating of 4-methylpentyl 3-methylbutanoate in chili pepper. Our findings shed light on the molecular mechanism of aroma biosynthesis in pepper and provide a theoretical basis for the molecular breeding of high-quality pepper fruits.

Characterization of Key Odor-Active Off-Flavor Compounds in Aged Pasteurized Yogurt by Sensory-Directed Flavor Analysis

The purpose of this study was to determine the key odor-active compounds contributing to the off-flavor of aged pasteurized yogurt (APY) using sensory-directed flavor analysis. Additionally, different extraction methods were compared to determine their effects on the volatile compounds, including dynamic headspace sampling (DHS), solid-phase microextraction, and stir bar sorptive extraction, and DHS was found to be suitable for this study. The results showed that comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry analysis (GC × GC-O-MS) had more advantages in separating and identifying the volatile compounds than the traditional GC-O-MS. A total of 17 odor-active compounds were determined in the fresh pasteurized yogurt and APY samples by DHS coupled with GC × GC-O-MS. The dynamic headspace dilution analysis demonstrated that 2-heptanone and hexanal were the most vital components in APY with the highest flavor dilution factor. Furthermore, the spiking and omission experimental results revealed that the odor-active compounds, such as 2-heptanone, butanoic acid, pentanoic acid, hexanal, and (E)-2-heptenal, were the key odor-active off-flavor contributors in APY. Therefore, these compounds could be used as potential indicators to determine the freshness of pasteurized yogurt.

Aroma-active compounds related to Maillard reaction during roasting in Wuyi Rock tea

Maillard reaction could be a breakthrough in standardizing the roasting process, which is a pivotal procedure in refining Wuyi Rock tea (WRT). This study aimed to find indicators to instruct the roasting process scientifically trying to provide theoretical support for actual production. A total of 86 volatile compounds were detected by solid-phase microextraction (SPME) coupled with gas chromatography–olfactometry–mass spectrometry (GC–O–MS) and GC×GC–O–MS in three rough WRTs leaves (RL) Dahonpao, Shuixian, and Rougui and three roasting degrees, light fire (LF), moderate fire (MF), and high fire (HF). Among them, 45 key aroma-active compounds with r-OAV> 1. Significant differences existed between RL/LF and MF/HF. The Maillard reaction primarily strengthened the roasted attributes but eliminated the individual characteristics through 1-ethyl-1H-pyrrole, 2-ethyl-5-methylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-3-methylpyrazine, furfural, and 5-methyl-2-furancarboxaldehyde. If combined with the analysis of amino acids, sugars, and polyphenols, eight aroma-active compounds relating to the Maillard reaction, furfural, 5-methyl-2-furancarboxaldehyde, 1-ethyl-1H-pyrrole-2-carboxaldehyde, 2-ethyl-5-methylpyrazine, 2-ethyl-6-methylpyrazine, 2,5-dimethyl-3-ethylpyrazine, 1-ethyl-1H-pyrrole, and methylpyrazine, could be considered as indicators to monitor the roasting process. The novelty of this result was that it provides the practical knowledge for further deep investigation from the perspective of the Maillard reaction and makes it possible to industrialize WRT manufacturing, rather than only relying on empiricism.

Characterization of key odor-active compounds in pure chicken powder and the effect of yeast extract, using instrumental and sensory techniques

Pure chicken powder (PCP) is a reliable source of mellow chicken soup flavor in seasoning, but it has some unstable compounds and is prone to lipid oxidation, which leads to unpleasant odor. Adding yeast extract (YE) can reduce the off-odor intensity of PCP. Based on the results of gas chromatography–olfactometry–mass spectrometry (GC–O-MS), two-dimensional comprehensive gas chromatography–olfactometry–mass spectrometry (GC×GC–O–MS) and combined aroma extract dilution analysis (AEDA), 14 key odor-active compounds were identified. Internal standard curve method was used for quantitative analysis, and the odor activity value (OAV) was calculated. Octanal, 1-octen-3-ol and hexanal were found to be the most vital odor-active compounds in PCP. The odor-active compounds of YE were studied by the same method, and dimethyl trisulfide was identified as the most important odor-active compound of YE. Additionally, recombination and omission experiments were carried out with PCP. Finally, it was found that a low concentration of dimethyl trisulfide had masking effect on the odor of PCP.

Study of aroma generation pattern during boiling of hot pot seasoning

Hot pot is popular among consumers because it provides a rich and multi-level flavor experience during boiling. In this study, the aroma compounds of hot pot seasoning (HPS) during different boiling times were characterized by comprehensive two-dimensional gas chromatography–olfactometry–mass spectrometry. Twenty-four aroma-active compounds with high flavor dilution (FD) factors were selected by aroma extract dilution analysis. Based on the odor activity values (OAVs), 23 key aroma-active compounds were identified as characterizing the main aroma profile of HPS during boiling. Furthermore, multivariate statistical analysis was used to screen out 10 key differential aroma-active compounds, which were used to distinguish the difference in aromas for HPS during the different boiling times. Finally, kinetic fitting was used to reveal the generation regularity of these 10 compounds. The results showed significant changes in the content of acetophenone, (E)− 2-heptenal and phenylacetaldehyde, conforming to first-order kinetics during boiling. However, other compounds were not well-fitted into the classical reaction kinetics models.

Switchable GC/GC × GC–olfactometry–mass spectrometry system for the analysis of aroma components of infant formula milk-based on cow and goat milk

The study sought to characterize the composition of volatile compounds and key aroma-active compounds of infant formulas (IF), which derived from cow's milk and goat's milk. The volatile aroma compounds were analyzed by the solid-phase microextraction (SPME) combined with a new switchable GC/GC × GC–olfactometry–mass spectrometry (SGC/GC2-O-MS) system, which can switch between one-dimensional and two-dimensional analysis modes and can realize the sniffing function under two-dimensional analysis conditions. The key aroma-active compounds were analyzed by the aroma extract dilution analysis (AEDA) and odor activity value (OAV). A total of 118 volatile compounds were identified in IF samples from 12 brands, of which 66 had aroma activity. These results revealed that hexanal had the highest FD factor but was not responsible for the difference between GS and CS. According to the results of OPLS-DA and VIP, it was helpful to screen for more important volatile compounds. (E)− 2-octenal, (E,E)− 3,5-octadien-2-one, (E,E)− 2,4-decadienal, 3-methylbutanal and 2-pentylfuran helped distinguish GS from CS.