Aroma Recombination Experiments Research Articles

Difference comparison of characteristic aroma compounds between braised pork cooked by traditional open-fire and induction cooker and the potential formation cause under electromagnetic cooking

The characteristic aroma compounds of braised pork were identified through molecular sensory science and PLSR analysis, and the difference between two cooking methods, traditional open-fire (BPF) and induction cooker (BPC), was compared. Seventeen aroma compounds with odor activity values (OAVs) > 1 were identified in both samples. BPF revealed higher OAVs for most of the aroma compounds compared to BPC, and the higher aroma quality. Aroma recombination and omission experiments confirmed that twelve aroma compounds significantly contributed to the characteristic aroma of braised pork, and eight compounds such as hexanal, (E)-2-octenal, and methanethiol were further confirmed as important contributors by PLSR analysis. Furthermore, PLSR analysis clarified the role of aldehydes such as hexanal, (E)-2-octenal, and (E,E)-2,4-decadienal in contributing to fatty attribute, whereas methanethiol was responsible for the meaty aroma. These characteristic aroma compounds mainly derived from lean meat due to its high content of phospholipids, and the exogenous seasonings contributed to the balanced characteristic aroma profile of braised pork by altering the distribution of these characteristic aroma compounds. Variations in heating parameters affected the formation of lipid oxidation and Strecker degradation products, which might explain aroma discrepancy between braised pork cooked by two methods with different heat transfer efficiencies.

Identification of key aroma‐active compounds in long shelf‐life yoghurt and milk produced by different pre‐sterilisation processes of raw milk using SBSE‐GC × GC–O–MS

SummaryAroma is a vital attribute of dairy products. This study employed a combination of human sensory evaluation and instrumental analysis to study the effect of two different pre‐sterilisation processes (A and B) on the odour characteristics of milk and long shelf‐life yoghurt. The results from the sensory evaluation and electronic nose analysis indicated that the pre‐sterilisation process significantly influences the aroma profile and compounds of the samples. Stir bar sorptive extraction coupled with comprehensive two‐dimensional gas chromatography−olfactometry−mass spectrometry (SBSE‐GC × GC−O−MS) was applied to identify the aroma‐active compounds present. Aldehydes and ketones emerged as the most abundant aroma‐active compounds. Quantitative analysis showed variations in the concentrations of aroma‐active compounds. For example, higher concentrations of hexanal, butanoic acid and hexanoic acid were observed in long shelf‐life yoghurt and milk produced by process B than process A, while higher concentrations of nonanal, 2,3‐butanedione and 3‐hydroxy‐2‐butanone were detected in products from process A than process B. Initial odour activity values provided insight into the contribution of aroma‐active compounds to the overall odour perception. Based on the results of aroma recombination, omission and spiking experiments, 13 and 11 key aroma‐active compounds were identified in long shelf‐life yoghurt and milk, respectively. These compounds, including 2,3‐butanedione, 2,3‐pentanedione, 2‐heptanone, 2‐undecanone, hexanal, octanal, nonanal, decanal, furfural, butanoic acid, hexanoic acid, 3‐hydroxy‐2‐butanone and styrene, can serve as potential indicators for determining odour differences between long shelf‐life yoghurt (milk) samples. Consequently, they offer a chemical basis for manufacturers to make informed decisions regarding production processes.

Variations in Key Aroma Compounds and Aroma Profiles in Yellow and White Cultivars of Flammulina filiformis Based on Gas Chromatography-Mass Spectrometry-Olfactometry, Aroma Recombination, and Omission Experiments Coupled with Odor Threshold Concentrations.

Flammulina filiformis (F. filiformis) is called the 'benefiting intelligence' mushroom. There is a notable difference between a yellow cultivar (with a robust aroma) and a white mutant cultivar (with a high yield) of F. filiformis. A thorough analysis of aroma differences is essential to improve the aroma of high-yield strains. This study employed a combination of gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and aroma extract dilution analysis (AEDA) to analyze the variations in aroma compounds. Then, the contribution of the odorants was determined using flavor dilution (FD) factors and odor activity values (OAVs). Aroma omission and recombination experiments were used to identify the key odorants. A total of 16 key aroma compounds were characterized in F. filiformis, along with four eight-carbon volatiles (3-octanone, 3-octanol, octanal, and 1-octen-3-ol). Finally, the dominant aroma characteristic was "sweet" for the yellow strain, while it was "green" for the white strain. More research is required to investigate the enzymes and corresponding genes that regulate the synthesis of aroma compounds in F. filiformis for future breeding programs.

Comparison of Aroma Compounds and Sensory Characteristics between Two Different Types of Rice-Based Baijiu.

Rice-based Baijiu has gained popularity in the Chinese market. Qingya-flavored Baijiu, a variant of Xiaoqu-fermented Baijiu, employs rice as its primary raw material, with an improved production process compared to traditional rice-flavored Baijiu. We comprehensively characterized and compared the aroma profiles of these two rice-based Baijiu types using static sensory experiments (QDA, quantitative descriptive analysis) and dynamic sensory experiments (TDS, temporal dominance of sensations). Qingya-flavored Baijiu exhibited pronounced plant, oily, and roasted aromas, while traditional rice-flavored Baijiu displayed more prominent fruity, floral, and sour notes. Utilizing GC-O-MS (gas chromatography-olfactometry-mass spectrometry) and multi-method quantification, we qualitatively and quantitatively analyzed 61 key aroma compounds, identifying 22 compounds with significant aroma contributions based on odor activity values (OAVs). Statistical analyses, combining sensory and chemical results, were conducted to predict important aroma compounds responsible for the aroma differences between the two Baijiu types. Aroma Recombination and Omission experiments showed that seven compounds play key roles in the aroma of Qingya-flavored Baijiu, including (2E,4E)-Deca-2,4-dienal, linalool, apricolin, ethyl acetate, ethyl isobutyrate, ethyl caprylate, and ethyl isovalerate.

Identification of the key aroma compounds in flaxseed milk using stir bar sorptive extraction, aroma recombination, and omission tests

Flaxseed milk is a plant-based dairy alternative that is rich in nutrients. Due to the low concentration of odor compounds in flaxseed milk, it cannot be completely extracted. This poses significant challenges for analysis. Therefore, this study developed a method suitable for extracting volatile compounds from flaxseed milk and compared it with three other extraction methods. It was found that Stir Bar Sorptive Extraction had the best extraction performance, identifying 39 odorants. Flavor dilution factors ranged from 1 to 512, with higher values observed for esters. 13 key odor compounds were identified (odor activity value > 1) using the external standard method for quantification; these included four aldehydes, three pyrazines, two alcohols, two esters, and two other compounds. Pyrazine compounds exhibited the highest concentrations. Aroma recombination and omission experiments showed that nine key odorants contributed significantly to the flavor profile of flaxseed milk, imparting aroma of cucumber, green, mushroom, fruity, sweet, and coconut.

Characterization of key aroma compounds in soy sauce flavor baijiu by molecular sensory science combined with aroma active compounds reverse verification method

The distinctive flavor profile of soy sauce flavor baijiu (SAB) is shaped by its unique aroma compounds. The characteristic aroma compounds in Langjiu soy sauce flavor baijiu (LSAB) were explored based on molecular sensory science. A total of 66 aroma active compounds were identified by gas chromatography–olfactometry (GC–O) combined with aroma extract dilution analysis (AEDA), and 6 important unknown sulfur compounds were identified using the aroma active compounds reverse verification method (ACRVW). A total of 39 key aroma compounds were determined to have odor activity values (OAVs) ≥ 1. The aroma contribution of aroma components was verified by aroma recombination and aroma omission experiments. 15 characteristic aroma compounds were identified in LSAB. Meanwhile, a simple and easy-to-understand sensory expression language was described to fully understand the style characteristics of LSAB. Overall, the present paper offers insights into research uncovering the key “sauce flavor” of soy sauce flavor baijiu.

Revealing the characteristic aroma and boundary compositions of five pig breeds based on HS-SPME/GC-O-MS, aroma recombination and omission experiments

To clarify the characteristic aroma compounds and flavor discrepancies of five Chinese typical pig species, headspace-solid phase microextraction gas chromatography–olfactometry-mass spectrometry (HS-SPME/GC-O-MS), electronic nose (E-nose), aroma recombination and omission experiments were used to analyze the characteristic aroma and boundary of five boiled pork. A total of 38 volatile compounds were identified, of which 14 were identified as important odorants with odor-activity values (OAVs) greater than 1. Aroma recombination and omission experiments revealed 8 key characteristic aroma compounds, which significantly contributed to the overall aroma. Sensory evaluation of the recombination model with the 8 aroma compounds scored 3.0 to 4.0 out of 5 points. 12 potential markers were identified to distinguish by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), including (E)-2-octenal, 3-ethyl-2-methyl-1,3-hexadiene, (E)-2-heptenal, 2-pentylfuran, cyclooctanol, 1-heptanol, sec-butylamine, D-limonene, N-vinylformamide, 2,3-octanedione, 2-ethylfuran and 3-pentanamine. Alongside benzaldehyde and pentanal, the combinations and fluctuations of these 14 aroma markers were proposed to constitute the aroma boundaries of different pork breeds. The aroma-active substances were able to effectively differentiate different breeds.

Sensomics-assisted key aroma molecules decoding of ginger-infused stewed beef

The utilization of ginger (Zingiber officinale Rosc.) is prevalent in beef cuisine for the purpose of flavor modification in China. The key aroma molecules in ginger-infused stewed beef were identified by sensomics methods. GC-MS (gas chromatography-mass spectrometry) identified 54 compounds. Nonanal, citral, β-bisabolene, α-terpineol, geraniol and endo-borneol were responsible for remarkable difference of stewed beef after ginger additions by orthogonal partial least squares-discriminant analysis (OPLS-DA). Seven aroma attributes were chosen for sensory analysis by check-all-that-apply (CATA) and free choice profiling method (FCP). Then, 23 compounds were perceived by gas chromatography-olfactometry (GC-O), and further quantified. Of these, 20 aroma-active compounds presented odor activity values (OAV) ≥ 1. Combined with aroma recombination and omission experiments, 19 compounds, including hexanal, β-myrcene, 2-acetylthiazole et al. were identified to be key contributors to characteristic aroma.

Characterization of key aroma compounds in Chinese smoked duck by SAFE-GC-O-MS and aroma-recombination experiments

Smoked duck is a popular meat product in China. The aroma profile and key aroma compounds in smoked ducks were elucidated using solvent-assisted flavor evaporation-gas chromatography–olfactometry-mass spectrometry (SAFE-GC-O-MS), odor activity values (OAVs), aroma recombination and omission experiments, and sensory evaluation. The results indicated that the predominant aroma profiles of rice-, tea oil- and sugarcane-smoked ducks all contained strong smoky, roasty, fatty, meaty, and grassy aromas. A total of 31 aroma compounds were identified as important odorants by OAVs, including 8 aldehydes, 6 pyrazines, 5 phenols, and 2 sulfur compounds. The aroma recombination and omission experiments confirmed that 13 odorants were key aroma compounds in smoked ducks. Of these odorants, 2-methoxyphenol, 4-methylphenol, 5-ethyl-2,3-dimethylpyrazine, methional, 2-methyl-3-furanthiol, (E, E)-2,4-decadienal, 1-octen-3-ol, and anethole significantly contributed to the aroma profile of smoked duck flavor (p < 0.01).

Characterization of the key odor-active compounds in different aroma types of Fu brick tea using HS-SPME/GC-MSO combined with sensory-directed flavor analysis.

Fu brick tea (FBT) is popular for its unique 'fungal flower' aroma, however, its key odor-active compounds are essentially unknown. In this study, the odor-active compounds of "stale-fungal" aroma (CJX), "fresh-fungal" aroma (QJX), and "fermentation-fungal" aroma (FJX) types FBT were extracted and examined by headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and gas chromatographyolfactometry (GC-O). A total of 43 volatile and 38 odor-active compounds were identified by these methods. Among them, the content of dihydroactindiolide (4596-13189µg/L), (E)-linalool oxide (2863-6627µg/L), and benzyl alcohol (4992-6859µg/L) were highest. Aroma recombination experiments further verified that these odor-active compounds could be simulated the overall aroma profile of FBT successfully. Furthermore, omission experiments confirmed that 15, 20, and 15 key odor-active compounds in CJX, QJX, and FJX FBT, respectively. This study will provide a theoretical basis for comprehensively understanding the formation of characteristic aromas in FBT.

Effect of shaking manners on floral aroma quality and identification of key floral-aroma-active compounds in Hunan black tea

Shaking is a key process effecting the floral aroma of Hunan black tea (HBT). In this study, the aroma composition of HBTs shaken in the early withering stage (ES1, ES1 + LS1, and ES2), shaken in the late withering stage (LS1), and not shaken (NS), and the identification of main floral aroma compounds were analyzed using sensory evaluation combined with gas chromatography-mass spectrometry (GC–MS), gas chromatography–olfactometry (GC-O), and aroma recombination experiments. Sensory evaluation results showed that the floral aroma of HBT shaken in the early withering stage was with high intensity, whereas HBT shaken in the late withering stage had low-intensity floral aroma. GC–MS identified a total number of 81 differential volatile compounds in HBT, including 30 esters, 18 aldehydes, 15 alcohols, 12 terpenes, 4 ketones, and 2 nitrogen-containing compounds. Further screening of important floral aroma differential compounds was performed using sensory-guided, odor activity value (OAV), and GC-O analysis, which identified three critical floral aroma differential compounds. Eventually, absolute quantification analysis and aroma recombination experiments confirmed that indole and methyl jasmonate were the most critical compounds of HBT determining floral aroma intensity. The findings of this study provide valuable guidance for the production of HBT with rich floral aroma attributes.

Effects of different over-fired drying methods on the aroma of Lu’an Guapian tea

Over-fired drying, a crucial process in the production of Lu’an Guapian (LAGP) tea, greatly enriches the tea’s aroma. In this study, the aroma compounds of LAGP tea processed through pulley charcoal drying (PCD), roller drying (RD), roller-conveyor drying (RCD), and hot air drying (HD) were analyzed using gas chromatography–mass spectrometry. A subsequent analysis of aroma extraction dilution analysis and odor activity values revealed that (E)-β-ionone, dimethyl sulfide, (E,E)-2,4-heptadienal, geraniol, linalool, benzeneacetaldehyde, coumarin, 2-ethyl-3,5-dimethyl-pyrazine, indole, hexanal, (Z)-jasmone, and (Z)-3-hexen-1-ol were the key contributors to the samples’ aroma variation. Moreover, a quantitative descriptive analysis and aroma recombination and omission experiments analysis revealed that (E)-β-ionone is the most critical contributor to the formation of floral aroma in tea processed using PCD, whereas (E,E)-2,4-heptadienal is responsible for the more pronounced fresh aroma in tea processed using HD. In addition, 2-ethyl-3,5-dimethyl-pyrazine contributes to the formation of a roasted aroma in tea processed using RD and RCD. The study results provide a theoretical basis for choosing the processing method, especially for drying, to obtain high-quality LAGP tea.

GC-O-MS Analysis of Aroma-Active Compounds of Chinese Almonds Obtained by Different Pretreatment Methods

Almonds (Prunus dulcis) are an ancient and commercially valuable crop from Asia. In this experiment, solid-phase microextraction (SPME), solvent-assisted flavor evaporation (SAFE), and simultaneous distillation extraction (SDE) were used to pretreat the almonds from China. The almond extract was then analyzed by aroma extract dilution analysis (AEDA) with gas chromatography-olfactory-mass spectrometer (GC-O-MS). SPME and SAFE were identified as the better extraction methods, and 52 aroma-active compounds of almonds, such as 1-nonanal, eugenol, and linalool, were identified based on odor activity values (OAVs). Aroma recombination and omission experiments showed that “sweet,” “fruity,” and “fatty” are the main aroma attributes of Chinese almonds, with a strong relationship with hexanal, heptaldehyde, 1-nonanal, etc. This experiment provides new insights into the sensory contribution of Chinese almond volatiles and helps Chinese almond producers characterize and market the aroma profile of Chinese almond varieties.

Characterization and modelling of odor-active compounds release behavior from Fu-brick tea during boiling-water extraction by molecular sensory science approach

The odor-active compounds in Fu-brick tea and their release behaviors during boiling-water were studied. Fifty-one odor-active compounds were identified, and their release behaviors were identified by continuously recovering 16 sections of condensed water combined with sensory, instrumental, and nonlinear curve fitting analysis. The odor intensities of condensed water and the concentrations of odor-active compounds could be significantly fitted (p < 0.01) to power-function type curves. Hydrocarbons showed the fastest release rate, while organic acids showed the slowest. The release rates had very little correlation with their concentrations, molecular weights, and boiling points. Most odor-active compounds (≥70 %) released need to evaporate more than 24 % of the added water during boiling-water extraction. Meanwhile, on the basis of odor activity value (OAV) calculation, the aroma recombination experiments were performed to explore the odor-active compounds that made major contributions to the formation of the aroma profile of each condensed water.

Sensory-directed establishment of sensory wheel and characterization of key aroma-active compounds for spicy tallow hot pot seasoning

The present study aimed to investigate the visual sensory profile of spicy tallow hot pot seasoning (STHPS) and characterize its aroma by the molecular sensory method. The flavor characteristics (numbing, pungent, umami, and fragrant) of STHPS were confirmed by visual sensory flavor analysis, and the sensory wheel of STHPS was mapped for the first time. A total of 85 aroma-active compounds were detected in STHPS by multiple extraction methods combined with comprehensive gas chromatography-olfactometry-mass spectrometry (GC × GC-O-MS). Of them, linalool (65.2-82.0 μg/g) and linalool acetate (15.4-37.5 μg/g) were the most abundant compounds in STHPS. Finally, 20 key aroma-active compounds were identified by aroma recombination and omission experiments, including linalool, (E)-2-decenal, etc. Aldehydes, nitrogen/sulfur compounds, and terpenes were responsible for intense fatty, meaty, roasted, sulfur/garlic-like, and spice-like aromas in STHPS.

Evaluation of key aroma compounds and protein secondary structure in the roasted Tan mutton during the traditional charcoal process.

The traditional charcoal technique was used to determine the changes in the key aroma compounds of Tan mutton during the roasting process. The results showed that the samples at the different roasting time were distinguished using GC-MS in combination with PLS-DA. A total of 26 volatile compounds were identified, among which 14 compounds, including (E)-2-octenal, 1-heptanol, hexanal, 1-hexanol, heptanal, 1-octen-3-ol, 1-pentanol, (E)-2-nonenal, octanal, 2-undecenal, nonanal, pentanal, 2-pentylfuran and 2-methypyrazine, were confirmed as key aroma compounds through the odor activity values (OAV) and aroma recombination experiments. The OAV and contribution rate of the 14 key aroma compounds were maintained at high levels, and nonanal had the highest OAV (322.34) and contribution rate (27.74%) in the samples after roasting for 10 min. The content of α-helix significantly decreased (P < 0.05), while the β-sheet content significantly increased (P < 0.05) during the roasting process. The content of random coils significantly increased in the samples roasted for 0-8 min (P < 0.05), and then no obvious change was observed. At the same time, β-turn content had no obvious change. Correlation analysis showed that the 14 key aroma compounds were all positively correlated with the content of α-helix and negatively correlated with the contents of β-sheet and random coil, and also positively correlated with the content of β-turn, except hexanal and 2-methypyrazine. The results are helpful to promoting the industrialization of roasted Tan mutton.

Variation in Volatile Compounds of Raw Pu-Erh Tea upon Steeping Process by Gas Chromatography-Ion Mobility Spectrometry and Characterization of the Aroma-Active Compounds in Tea Infusion Using Gas Chromatography-Olfactometry-Mass Spectrometry.

Steeping process is an important factor for aroma release of tea, which has rarely been investigated for the aroma changes of raw Pu-erh tea (RAPT). In addition, the comprehensive aroma characteristics identification of RAPT infusion is necessary. In this study, GC-IMS coupled with principal component analysis (PCA) was used to clarify the difference of volatile profiles during the steeping process of RAPT. Furthermore, the volatiles contained in the RAPT infusion were extracted by three pretreatment methods (HS-SPME, SBSE, and SAFE) and identified using GC-O-MS. According to the odor activity value, 28 of 66 compounds were categorized as aroma-active compounds. Aroma recombination and omission experiments showed that "fatty", "green", "fruity", and "floral" are considered to be the main aroma attributes of RAPT infusion with a strong relationship with 1-octen-3-one, 1-octen-3-ol, (E)-2-octenal, β-ionone, linalool, etc. This study will contribute a better understanding of the mechanism of the RAPT steeping process and volatile generation.

Characterization of volatile composition, aroma-active compounds and phenolic profile of Qingxin oolong tea with different roasting degrees

Due to the premium flavor, Qingxin oolong tea (QOT), which is grown and produced in Taiwan, is widely appreciated. Roasting is a crucial process for shaping its flavor. However, the effect of roasting on the aroma and taste of QOT was not fully understood. In this study, the volatile composition, aroma-active compounds and phenolic profile of QOT with different roasting degrees, including the unroasted (UR), the medium roasted (MR) and the heavy roasted (HR) were analyzed. As revealed by headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and multivariate statistical analyses, UR and MR demonstrated similar volatile profiles, while heavy roasting changed the volatile composition greatly. Multiple nitrogen-containing compounds, such as 3,5-diethyl-2-methylpyrazine and 2-ethyl-3,5-dimethylpyrazine, were uniquely found in heavy roasted samples, which can be ascribed to the extensive Maillard reaction. Moreover, eight compounds were identified and verified as key aroma-active compounds by using gas chromatography-olfactometry-mass spectrometry (GC-O-MS), aroma recombination and omission experiments. The aldehydes and alcohols, such as linalool, benzeneacetaldehyde and α-farnesene, with a floral scent were the dominant aroma-active compounds in UR and MR, while 2-ethyl-3,5-dimethylpyrazine and 3,5-diethyl-2-methylpyrazine with a roasted scent were the main aroma-active compounds in HR. Furthermore, as revealed by ultra-high performance liquid chromatography and Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap-MS), flavanols and phenolic acids were significantly lower in abundance in UR and MR as compared to those in HR, whereas flavonols were less affected by roasting. These findings provide useful information for understanding the flavor characteristics of this popular oolong tea for the first time.

Characterization of key aroma compounds in traditional beef soup

This study aimed to identify the characteristic aroma compounds of beef soup and analyze the differences between their aroma. Seven beef soup samples were analyzed by sensory evaluation combined with gas chromatography−mass spectrometry (GC–MS) and electronic nose (E-nose). A total of 80 volatile compounds were identified, and seven key aroma compounds in beef soup samples were determined by odor activity value, sensory evaluation, aroma recombination and omission experiments. They were linalool, (E)-3,7-dimethyl-2,6-octadien-1-ol, nonanal, (E)-2-octenal, 3,7-dimethyl-2,6-octadienal, 2-acetylthiazole and estragole. The panelists described the organoleptic characteristics of beef soup as beef meaty, spice, fatty, caramel, and roasted. GC–MS and E-nose combined with principal component analysis showed different aroma profiles among beef soup samples. A total of 30 potential differential markers were screened by partial least squares discriminant analysis. The difference between samples was mainly caused by the type and content of compounds.

Characterization of key aroma compounds in low-salt fermented sour fish by gas chromatography-mass spectrometry, odor activity values, aroma recombination and omission experiments

In this study, key aroma compounds of low-salt fermented sour fish were characterized using headspace solid-phase micro extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC–MS), odor activity values (OAV) and aroma recombination and omission experiments. Eighty-eight volatile compounds, including esters, aldehydes, alcohols, acids, furans and pyrazines, were identified by HS-SPME-GC–MS. Eighteen aroma-active compounds were quantified by employing calculation of OAV greater than 1. A recombination aroma model prepared using aroma-active compounds based on the odorless fish matrix sensorially matched the aroma of fermented sour fish with a score of 4.5 out of 5. The omission experiment showed that 7 out of 18 compounds had a significant contribution to the overall aroma (P < 0.05). The key aroma compounds of fermented sour fish were concluded to be ethyl acetate (OAV = 189), ethyl hexanoate (OAV = 66), isoamyl acetate (OAV = 424), ethyl butyrate (OAV = 26), hexanal (OAV = 49), 1-hexadecanal (OAV = 14) and 2-pentylfuran (OAV = 13).