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Characterization and comparison of key aroma compounds in traditional and rapid Yongchuan douchi by molecular sensory science
... For example, fermented soybeans at 37 • C enhance soybean flavor compared to those at 45 • C and 53 • C, while fermented soybeans at 45 • C and 53 • C enhance soy sauce-like flavor compared to those at 37 • C [5]. Although traditional soybean flavor products such as Douchi and Chi-flavor-type Baijiu are popular and accepted worldwide due to their prominent soybean flavor [6,7], there are only a few reports on the study of soybean flavor. It is speculated that the synergistic effects of multiple metabolic pathways and multiple genes may produce soybean flavor [5]. ...
... Furthermore, Mathatheeranan et al. identified the dominant aroma compounds of thua nao (indigenous Thai fermented soybeans) fermented by commercial B. subtilis under controlled conditions including 2-methylbutyric acid, phenylethyl alcohol, benzaldehyde, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, and 2-methoxyphenol, which contribute to the fermented/sour, floral, almond-like, and nutty aromas of fermented soybeans [13]. More recently, GC-O-MS combined with relative odor activity values (ROAV) were applied to examine the aroma compounds of sufu [14], Yongchuan Douchi [6], typical fermented soy foods [15], and so on. In these studies, e-nose analysis and quantitative description sensory analysis (QDA) were used to analyze the aroma profiles of different fermented soy products. ...
Soybean flavor is considered to be essential for the aroma quality of fermented soybeans (FS) with Bacillus subtilis BJ3-2 (BJ3-2) at 37 °C. However, the key aroma compounds of the soybean flavor must be further elucidated. In this study, two candidate genes (sdaAA and katX) of BJ3-2 involved in the control of soybean flavor production were screened using prior multi-omics data. FS samples with BJ3-2, BJ3-2ΔsdaAA, BJ3-2ΔkatX, and BJ3-2ΔsdaAAΔkatX were analyzed by quantitative descriptive sensory analysis (QDA), gas chromatography–olfactometry–mass spectrometry (GC-O-MS), relative odor activity values (ROAV), and aroma addition experiments. The QDA revealed that the aroma profile of the soybean flavor in FS consisted of “sweaty”, “smoky”, “beany”, “roasted”, and “sweet” attributes. A total of 20 aroma-active compounds were detected, and 13 of them with ROAV > 1 were identified as key aroma compounds. Moreover, aroma addition experiments were conducted to further confirm the key aroma compounds of soybean flavor. Among them, 2-methylbutyric acid, 2,3,5-trimethylpyrazine, and guaiacol contributed higher aroma intensity values and ROAV, resulting in “sweaty”, “roasted”, and “smoky” attributes of soybean flavor in FS, respectively, while 1-octen-3-ol was associated with the “beany” attribute. These findings provide novel insights into the aroma attributes of soybean flavor in FS and a new strategy for revealing the key aroma compounds in fermented foods.
A novel Chinese-style sausage with Chinese traditional fermented condiments used as additional ingredients is produced in this study. The aim of this study was to investigate the microbial community’s structure, the volatile flavor substances and their potential correlation in the novel Chinese sausage. High-throughput sequencing (HTS) and solid-phase microextraction-gas chromatography-mass spectrometry (GC-MS) were, respectively, used to analyze the microbial diversity and volatile flavor substances of the novel Chinese-style sausage during storage. The results showed that Firmicutes, Proteobacteria and Actinobacteria were the predominant bacterial genera, and Hyphopichia and Candida were the predominant fungal genera. A total of 88 volatile flavor substances were identified through GC-MS, among which 18 differential flavor compounds were screened (VIP > 1), which could be used as potential biomarkers to distinguish the novel sausages stored for different periods. Lactobacillus exhibited a significant negative correlation with 2,3-epoxy-4,4-dimethylpentane and acetoin and a significant positive correlation with 2-phenyl-2-butenal. Hyphopichia significantly positively correlated with ester. Leuconostoc significantly positively correlated with ethyl caprate, ethyl palmate, ethyl tetradecanoate and ethyl oleate while it negatively correlated with hexanal. This study provides a theoretical basis for revealing the flavor formation mechanisms and the screening of functional strains for improving the flavor quality of the novel Chinese-style sausage.
Yongchuan douchi is a traditional fermented soya bean product which is popular in Chinese dishes due to its unique flavor. In this study, the key aroma-active compounds of Yongchuan douchi were characterized by the combined gas chromatography–olfactometry (GC–O) and gas chromatography−mass spectrometry (GC–MS) with sensory evaluation. In total, 49 aroma compounds were sniffed and identified, and 20 of them with high flavor dilution factors (FD) and odor activity values (OAVs) greater than one were screened by applied aroma extract dilution analysis (AEDA) and quantitated analysis. Finally, aroma recombination and omission experiments were performed and 10 aroma-active compounds were thought to have contributed significantly including 2,3-butanedione (butter, cheese), dimethyl trisulfide (garlic-like), acetic acid (pungent sour), acetylpyrazine (popcorn-like), 3-methylvaleric acid (sweaty), 4-methylvaleric acid (sweaty), 2-mehoxyphenol (smoky), maltol (caramel), γ-nonanolactone (coconut-like), eugenol (woody) and phenylacetic acid (flora). In addition, sensory evaluation showed that the flavor profile of Yongchuan douchi mainly consisted of sauce-like, sour, nutty, smoky, caramel and fruity notes.
Aim:
To identify core bacterial communities and volatile compounds and to investigate their relationships in Doubanjiang, a Chinese traditional red pepper paste.
Methods and results:
Two main culture-independent methods, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and MiSeq sequencing technique, were used to investigate bacterial composition. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to isolate and identify volatile organic compounds. Partial least squares (PLS) regression and correlation coefficients analyses were used for elucidating the relationship between core bacterial community and volatile compounds.
Conclusions:
Lactic acid bacteria (LAB) and family Enterobacteriaceae were identified primarily by the PCR-DGGE fingerprinting. Furthermore, the core microbiome (>1% average relative abundance) were indentified by Miseq sequencing technique, which mainly assigned to Proteobacteria, Cyanobacteria and Firmicutes phyla. For volatile profile, a total of 29 volatile compounds were identified by HP-SPME-GC-MS, mainly alcohols, esters, aldehydes, ketones and phenols. PLS regression and pearson's correlation coefficients analyses revealed highly covariable relationships between volatile compounds and bacterial taxa. Notably, Pseudomonas most highly significantly associated with 3-methyl butanal, 2-methyl butanal, benzeneacetaldehyde and 2-acetylpyrrole (P < 0.001), and significantly correlated with 5-methylfurfural and 5-methyl-2-phenyl-2-hexenal (P < 0.01).
Significance and impact of the study:
Core bacterial communities were identified and the relationship between bacterial taxa and flavor compounds was revealed, these results could be beneficial for improving the quality of Doubanjiang. This article is protected by copyright. All rights reserved.
Aroma extract dilution analysis (AEDA) is widely used for the screening of aroma-active compounds in gas chromatography-olfactometry (GC-O). In this study, three aroma dilution methods, (I) using different test sample volumes, (II) diluting samples, and (III) adjusting the GC injector split ratio, were compared for the analysis of volatiles by using HS-SPME-AEDA. Results showed that adjusting the GC injector split ratio (III) was the most desirable approach, based on the linearity relationships between Ln (normalised peak area) and Ln (normalised flavour dilution factors). Thereafter this dilution method was applied in the analysis of aroma-active compounds in Japanese soy sauce and 36 key odorants were found in this study. The most intense aroma-active components in Japanese soy sauce were: ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl 4-methylpentanoate, 3-(methylthio)propanal, 1-octen-3-ol, 2-methoxyphenol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-vinylphenol, 2-phenylethanol, and 4-hydroxy-5-ethyl-2-methyl-3(2H)-furanone.
Copyright © 2015. Published by Elsevier Ltd.
To characterize the key odorants of floral aroma green tea (FAGT) and reveal its dynamic evolution during processing, the volatile metabolites in FAGT during the whole processing were analyzed by integrated volatolomics techniques, relative odor activity value (rOAV), aroma recombination, and multivariate statistical analysis. The volatile profiles undergone significant changes during processing, especially in the withering and fixation stages. A total of 184 volatile compounds were identified (∼53.26% by GC-MS). Among them, 7 volatiles with rOAV > 1 were identified as characteristic odorants of FAGT, and most of these compounds reached the highest in withering stage. According to the formation pathways, these key odorants could be divided into four categories: fatty acid-derived volatiles, glycoside-derived volatiles, amino acid-derived volatiles, and carotenoid-derived volatiles. Our study provides a comprehensive strategy to elucidate changes in volatile profiles during processing and lays a theoretical foundation for the targeted processing of high-quality green tea.
The volatile fraction was isolated from the premium and common grade of Lu'an Guapian green tea infusion by solvent-assisted flavor evaporation distillation. With the application of aroma extract dilution analysis, a total of 52 aroma-active compounds were revealed in the flavor dilution (FD) factor area of 32-8192. Besides, five additional odorants with higher volatility were identified using solid-phase microextraction. The aroma profiles, FD factors, and quantitative data of premium Guapian (PGP) and common Guapian (CGP) showed apparent differences. The intensity of the flowery attribute was significantly higher in PGP than in CGP, while cooked vegetable-like was the most outstanding odor note in CGP. The recombination experiment and the omission test of PGP clarified that dimethyl sulfide, (E,E)-2,4-heptadienal, (E)-β-ionone, (E,Z)-2,6-nonadienal, 2-methylbutanal, indole, 6-methyl-5-hepten-2-one, hexanal, 3-methylbutanal, γ-hexalactone, methyl epijasmonate, linalool, geraniol, and (Z)-3-hexen-1-ol were the key odorants of PGP tea infusion. The omission and addition tests of flowery odorants manifested that (E)-β-ionone, geraniol, and (E,E)-2,4-heptadienal, with higher odor activity values in PGP than in CGP, contributed to the flowery attribute most. The difference in the concentration of the abovementioned odorants with flowery odor notes could be one of the main factors which led to the difference in aroma quality between the two grades of Lu'an Guapian.
Most previous studies on volatile compounds in soy sauce were performed by gas chromatography-mass spectrometry (GC-MS). In this study, the volatile compounds of high-salt liquid-state fermentation soy sauce (HLFSS) were analyzed qualitatively and quantitatively by GC-MS and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). One hundred and seventy-four substances were detected using the two instruments, 87 by HS-GC-IMS and 127 by GC-MS. Aldehydes (26), ketones (28), esters (29), and alcohols (26) were the main compounds in HLFSS. In addition, ethyl pyruvate, (E)-2-pentenal and diethyl propanedioate were detected by HS-GC-IMS, which were previously not detected in HLFSS. Forty-eight aromatics including 34 key ones were identified by gas chromatography-olfactometry. Phenylacetaldehyde, methional, 2-methylbutanal, 1-octen-3-ol, ethyl acetate, 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 4-ethyl guaiacol were identified as the main aroma compounds in HLFSS by aroma recombination and omission test. This study laid foundation for developing flavor assessment standards for soy sauce.
Mucor racemosus is the predominant fungal in the zhiqu stage of the fermentation of Yongchuan Douchi (Mucor-type), which plays an important role in the fermentation process of Yongchuan Douchi. However, there is a lack of information on the genetic analysis of M. racemosus. In this study, we isolated and identified M. racemosus C (accession no JAPEHQ000000000) from Yongchuan Douchi and analyzed the physiological indicators, then genomic information of the strain to perform a comprehensive analysis of its fermentation capacity and safety. M. racemosus C had neutral protease activity up to 68.051 U/mL at 30 °C and alkaline protease activity up to 57.367 U/mL at 25 °C. In addition, comparing the genomic data with the COGs database (NCBI), it was predicted that M. racemosus C undergoes extensive amino acid metabolism, making C suitable for the production of fermented foods (e.g., Douchi, Syoyu, and sufu). Finally, we performed virulence genes and resistance genes analysis, hemolysis experiment, aflatoxins assay, antibiotic resistance assay to evaluate the safety of M. racemosus C, and the results showed that M. racemosus C was safe, non-toxin-producing and non-hemolytic.
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.
To comprehensively analyse flavour substance formation in Congou black tea, dynamic changes in non-volatile and volatile compositions and enzymatic activity were analysed. In total, 107 non-volatile and 222 volatile compositions were identified via ultra-high performance liquid chromatography coupled with quadrupole-exactive mass spectrometry (UHPLC-Q-Exactive/MS) and stir bar sorptive extraction-gas chromatography-mass spectrometry (SBSE-GC-MS), and eight metabolic pathways were explored during tea processing. Significant variations in metabolites were observed during processing (P < 0.05), especially in the fermentation stage, including high accumulation of taste and colour substances due to decreased flavonoid synthase activity and elevated oxidase activity. Correlation analysis clarified that the mutual transformation between non-volatile and volatile substances occurs in certain types of processing, including amino acids, amino acid-derived volatiles (AADVs), glycosidically bound volatiles (GBVs), and volatile terpenoids (VTs). Our study provides a detailed overview of the dynamic changes of in flavour substrates and key enzyme activities during Congou black tea processing.
Aroma extract dilution analysis was performed on volatile fractions extracted from a freshly prepared Dahongpao (DHP) tea infusion using solvent-assisted flavor evaporation, yielding 65 odor-active domains with flavor dilution factors ranging between 32 and 32,768. In addition, six aromatic substances were captured by headspace analysis. Quantitation of 54 compounds by an internal standard method and stable isotope dilution assays revealed that the concentrations of 32 odorants exceeded their respective orthonasal odor threshold values in tea infusion. The results of odor activity values (OAVs) suggested that 2-metylbutanal (malty) and γ-hexalactone (coconut-like) had the highest OAVs (248 and 154). Eight odorants including γ-hexalactone (OAV 154), methyl 2-methylbutanoate (59), phenylacetic acid (7.2), acetylpyrazine (5.7), 2-methoxyphenol (3.4), p-cresol (2.7), 2,6-diethylpyrazine (2.7), and vanillin (1.8) were newly identified as key odorants in DHP tea infusion. An aroma recombination model in a non-volatile matrix extracted from tea infusion satisfactorily mimicked the overall aroma of DHP tea infusion, thereby confirming the identification and quantitative experiments. Omission experiments verified the obvious significance of 6-methyl-5-hepten-2-one (OAV 91), 2-ethyl-3,5-dimethylpyrazine (19), 4-hydroxy-2,5-dimethylfuran-3(2H)-one (13), and acetylpyrazine (5.7) as key odorants for the special roasty and caramel-like aroma of DHP tea.
The warmed-over flavor (WOF) in surimi gels was characterized by gas chromatography-ion mobility spectrometry, aroma extract dilution analysis, aroma recombination, and omission studies. Surimi gels with different WOF levels were prepared by different gelling temperatures, and surimi gels heated at 90, 100, and 121 °C were considered as the samples with light, strong, and medium WOF, respectively. Based on the quantification and odor activity values, 14 aldehydes, 2 ketones, 3 alcohols, 2 benzene-containing compounds, 2 N-containing compounds, 3 S-containing compounds, 3 lactones, undecanoic acid, and 4-methylphenol were recombined to build a spiked model for surimi gels with the strongest WOF, which showed the highest similarity with the original sample. Finally, a triangle test involving omission of the aroma compounds from the spiked model proved that the WOF in surimi gels was attributed to (E,E)-2,4-decadienal, heptanal, octanal, nonanal, decanal, (E)-2-nonenal, (E)-2-octenal, (E)-2-decenal, (E,E)-2,4-heptadienal, 2,3-pentanedione, 2,6-dimethylpyrazine, 2-propylpyridine, benzothiazole, 2-methoxybenzenethiol, and 2-furfurylthiol.
Chinese indigenous pigs are favored for their rich flavor, which is generated through complex reactions involving lipid-oxidation-related flavor precursors. In this research, we characterized the aroma compounds and fatty acids of representative Chinese pig breeds by gas chromatography–olfactometry–mass spectrometry (GC–O–MS) and GC–ion mobility spectrometry (GC–IMS) with multivariate analysis. A total of 79 volatile compounds were identified, among which 15 compounds were selected as odorants in pork. According to multivariate statistical analysis, some odorants, including hexanal, 1-octen-3-ol, 2,3-octanedione, (E, E)-2,4-decadienal and dodecanal could be discriminative compounds explaining breed-originated differences in flavor profiles. As confirmed by partial least squares regression (PLS-R), some fatty acids, including C18:1n9c, C22:6n3 and C18:3n3, were major precursors for the formation of rich flavor in indigenous pig breeds. These results revealed that fatty acids and volatile compounds were breed-dependent, and the differences in flavor were related to the variance in the fatty acid content.
Dianhong tea (DHT) is popular for its pleasant caramel-like aroma. In this study, the aroma profile of high-grade DHT have been studied using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) combined with headspace solid phase microextraction (HS-SPME). A total of 52 aroma-active compounds were identified by GC-O coupled with aroma extract dilution analysis (AEDA) and odor specific magnitude estimation (Osme). Among them, quantification of 21 aroma-active compounds indicated that the content of linalool (5928 µg/kg) was the highest in high-grade DHT, followed by phenylethanol (3923 µg/kg) and phenylacetaldehyde (1801 µg/kg). Sensory-directed aroma recombination and omission tests further verified that phenylacetaldehyde, linalool, geraniol and 3-ethyl-2,5-dimethylpyrazine were important contributors to the overall sensory characteristics of high-grade DHT which dominated mainly by floral, sweet and caramel-like odors. This work will provide a theoretical reference for comprehensively understanding the aroma characteristic of DHT.
This was the first study to compare the key aroma-active compounds that contributed to the different aroma profiles between roasted and cold-pressed sesame oils. Aroma compounds were extracted by headspace solid-phase micro-extraction (HS-SPME) and simultaneous distillation extraction (SDE) and were analysed using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA). The numbers of aroma-active compounds with the flavour dilution (FD) factors between 1 and 2048 were 57 and 16 in the roasted and cold-pressed sesame oils, respectively. A total of 28 volatile compounds were identified as aroma-active compounds in sesame oils for the first time. Important aroma compounds (FD≥8) were quantified by the external standard method, and their odour activity values (OAV) were calculated as the ratio of their concentrations to odour thresholds in oil. The numbers of key aroma-active compounds defined by OAVs≥1 were 23 (OAVs= 1-385) and 8 (OAVs= 1-42), respectively, in the roasted and cold-pressed sesame oils. 2-Methoxy-4-vinylphenol (smoked, 1924 µg/kg, OAV=385), 2-methoxyphenol (smoked, 1488 µg/kg, OAV=114) and pyrazines (roasted and nutty, 578-22750 µg/kg, OAV=1-67) were the most important aroma-active compounds in the roasted sesame oil, whereas hexanal (green and fruity, 3094 µg/kg, OAV=42) was the most important aroma-active compound in the cold-pressed sesame oil, followed by (E,E)-2,4-decadienal (earthy, 4170 µg/kg, OAV=31), dimethyl sulfone (sulphur-like, 406 µg/kg, OAV=20) and octanal (green and fruity, 901 µg/kg, OAV=16). This study provides valuable information for manufacturers to achieve precise flavour control of sesame oil products.
Liquid–liquid microextraction (LLME) combined with gas chromatography–olfactometry–mass spectrometry (GC–O–MS) was used to detect the variations in volatile compounds during the distillation process (head, heart, and tail) of raw Baijiu produced by different layers of fermented grains; 47 aroma compounds were sniffed and identified. Moreover, temperature-programmed headspace gas chromatography–ion mobility spectrometry (TP-HS–GC–IMS) was applied to characterize the Baijiu distillation process for the first time. The 3D fingerprint spectrum clearly showed a variation in volatile compounds from different distillation stages, and most compounds showed a downward trend. In addition, multivariate statistical analysis, including principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), etc., confirmed ten aroma active markers related to classification, indicating that these markers had a great influence on the flavor of raw Baijiu.
Black soybean sauce’s (BSS) aroma was scarcely investigated, which seriously affected BSS’s quality and consumers’ preference. Thus the aroma compounds in BSS were characterized using gas chromatography-mass spectrometry/gas chromatography-olfactometry coupling with recombination and omission experiments. Sensory evaluation showed the fruity odor was increased by 63% and the malty, alcoholic, floral, smoky, caramel-like and sour odors were decreased by 24–35% when compared to the control soy sauce (SS, p < 0.05). Totally, 126 volatile compounds, 44 aroma-active compounds and 22 vital aroma-active compounds were identified in BSS. Compared to SS, BSS exhibited a distinctive aroma characteristics which was caused by significantly higher odor activity values (OAVs) of 3-methylbutyl acetate (357%), ethyl propanoate (144%), ethyl 3-methylbutanoate (70%), ethyl 2-methylbutanoate (102%) and lower OAVs of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (52%), 4-hydroxy-2-ethyl-5-methyl-3(2H)-furan-3-one (50%), ethanol (48%), 4-vinylguaiacol (41%), 3-methylthiopropanal (37%), 3-methylbutanol (33%), 4-ethylguaiacol (28%). The results would contribute to BSS’s quality control and aroma improvement.
Chinese horse bean-chili-paste (CHCP), a fermented condiment in China, is traditionally manufactured through naturally spontaneous semi-solid fermentation procedures without intentionally inoculated microorganisms. The aim of this study was to investigate the effect on microbiota and quality variations during CHCP fermentation by inoculation of selected autochthonous microorganisms Bacillus amyloliquefaciens and Candida versatilis. The results showed that relative abundance of Bacillus in the samples inoculated with B. amyloliquefaciens were increased from about 0.6% to almost 25%, and the batches bio-augmented with C. versatilis exhibited clearly 0.7 Lg copies/g higher biomass than that of the other samples. By bio-augmentation, six enzyme activities, namely acid protease, leucine aminopeptidase, α-amylase, cellulose, β-glucosidase and esterase, were considerably enhanced. As a result, inoculation of these two strains exhibited significant effect on the volatile profiles of CHCP. B. amyloliquefaciens herein was found to contribute mainly to the accumulation of acids, sulfur-containing compounds and pyrazines, whereas C. versatilis was considerably associated with the formation of alcohols, esters and phenols. This study proved that combination of B. amyloliquefaciens and C. versatilis could obtain more extensive aroma profiles, especially for the enrichment of miso-like and fruity flavors, which could provide a guideline for the tailored control of CHCP fermentation process.
The aroma compounds and the microbial community of oil furu, a specific fermented soybean curd, during fermentation were investigated using HS-SPME-GC/MS and high-throughput sequencing, respectively, and their correlations and the predicted functional roles of the microbiota in oil furu were analyzed. Twenty two volatile flavor compounds (relative odor activity value ≥1) were identified that contributed to the aroma profile, which were mainly associated with the aroma attributes. Lactobacillales, Trichosporon and Mucor racemosus were the predominant genera during pre-fermentation, while Candida and Tetragenococcus were predominant during ripening. Correlation analysis showed significant correlation between the microbiota and aroma profiles, and Candida, Empedobacter, Lactobacillus, Pseudomonas, Stenotrophomonas, Trichosporon and Mucor racemosus were significantly and strongly correlated with the characteristic volatile aroma compounds of oil furu (P <0.05, r >0.6). Functional analysis showed that metabolic pathways showed higher activity in oil furu, which mainly included amino acid, lipid and carbohydrate metabolism. The results allowed identification of the important aroma compounds and understanding the contribution of the microbiota, and would be useful for designing starter cultures to produce oil furu with desirable aroma properties and understanding its aroma formation pathways.
Fruity notes are important to the flavor of Baijiu (Chinese Liquor) and are considered to originate from ester compounds; however, little is known about the other chemicals that contribute to the fruity aroma. In this study, the sensory impacts of two tropical fruit aroma thiols, 3-mercaptohexanol (3MH) and 4-methyl-4-mercapto-2-pentanone (4MP), in Chinese Light-, Strong- and Soy sauce flavor type Baijiu were systemically subjected to a sensory evaluation, qualitative and quantitative analysis, and multivariate statistical analyses. The flavor dilution factors of 3MH and 4MP were 9-729. The contents of 3MH and 4MP were the highest (p<0.001) in Strong- and Soy sauce aroma-type Baijiu, respectively. According to their odor activity values (OAVs), 3MH (OAV: 1-22) and 4MP (OAV: 1-9) are important to the aroma of Baijiu. Notably, 4MP was identified for the first time in Baijiu, and the multivariate statistical analysis demonstrated that 3MH and 4MP could be used to differentiate Baijiu.
Characterization of volatile off-odor compounds in thermal duck egg gels was investigated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS), odor activity values (OAVs) and aroma recombination. The results demonstrated that the off-odor of thermal duck egg mainly came from egg yolk (EY), and content of aldehydes was the highest in EY. Anaerobic treatment in nitrogen contributed to decreased off-odor sensory scores and volatile components of the heated egg gels. Aerobic EY gels (treated in air) were determined to contain eight volatile compounds with OAVs greater than 1, such as hexanal, nonanal, benzaldehyde, (E)-2-octenal, (E)-2-nonenal, (E, E)-2,4-decadienal, 1-octen-3-ol and 2-pentylfuran. However, three key volatile components (nonanal, benzaldehyde and (E)-2-nonenal) with OAVs greater than 1 were found in anaerobic EY gels. Moreover, on the basis of results of recombination and omission experiments, hexanal, (E)-2-octenal, (E, E)-2,4-decadienal, 1-octen-3-ol and 2-pentylfuran were identified as key off-odor components in thermal EY gels. Sensory evaluation of the recombination model with five aroma compounds scored 4.38 out of 5 points. The major aroma profile of the off-flavor from egg EY gels included strong fatty, nutty, and mushroom aromas.
Camellia oil is a popular edible oil in China as a result of its nutritional properties. However, the key odorants of camellia oil remain unclear. In this study, the volatiles of virgin camellia oil (VCO) were extracted by solvent-assisted and non-solvent-assisted methods. A total of 66 volatile compounds were identified using gas chromatography-mass spectrometry-olfactometry, with flavor dilution factors ranging from 1 to 729 via aroma extraction dilution analysis. Among them, 10 odorants were identified for the first time in VCO. Moreover, 41 volatiles were confirmed as aroma-active compounds with odor activity values greater than 1. Aroma recombination and omission studies demonstrated that aldehydes, esters, acids, and heterocyclic compounds significantly contribute to the aroma profiles of VCO. Hexanal, octanal, (E,E)-2,4-heptadienal, (E,E)-2,4-nonadienal, decyl acetate, ethyl benzoate, ethyl 2-methylbutanoate, 2-methylbutyl (Z)-2-methyl-2-butenoate, 2-methylbutanoic acid, hexanoic acid, 2-pentylfuran, and 2-methyl-3-furanthiol could impart roasted-like, nut-like, fat-like, fruit-like, grass-like, and sweat-like odors and were the key odorants in VCO. The lipoxygenase pathway was possibly responsible for the formation of key odorants in VCO. This work provides an extract aroma consistent for virgin camellia oil.
Yongchuan douchi is a traditional fermented food in China. This study investigated the microbial community of two major types (Natural and artificial) of Yongchuan douchi, and their influences on quality. The results found that natural-type douchi had significantly better quality in its physicochemical properties such as higher amino nitrogen, darker color, and higher umami amino acids after post-fermentation (p < 0.05). A total of 58 volatile components were found in natural-type douchi compared to artificial-type with 42 identified. Microbial analysis found that natural-type douchi had the richness and diversity of the bacterial (fungus) community. However, artificial-type douchi was high in Candida genera may associated with its bitter after taste compared to natural-type. Following post-fermentation, natural-type douchi had higher abundance of Bacillus sp., Enterobacter sp., and Pseudomonas sp., while Bacillus sp., Weissella sp., and Aspergillus sp. compared to artificial-type douchi. Correlation analysis showed that physicochemical properties and sensory quality could be correlated positively or negatively with the microbial composition during the last stage of post-fermentation. In conclusion, the zhiqu process significantly affected the final quality of the two types of Yongchuan douchi as evidenced by the microbial composition in the post-fermentation process.
Fermentation with excellent aroma-producing yeasts can enhance the flavour of soy sauce. In this work, Millerozyma farinosa CS2.23, Zygosaccharomyces rouxii CS2.42, and Candida parapsilosis CS2.53 were added to the high-salt liquid-state moromi to promote soy sauce fermentation. All three yeasts improved the TE of soy sauce, the highest of which reached 1.03 g/L with added CS2.42. Other quality indexes of soy sauce, including RS, TA, and AN, were not greatly affected. The volatile esters of soy sauce added to the three yeasts increased by 108.85%, 166.71%, and 113.61% compared with the control through GC-MS analysis. Obviously, CS2.42 had an excellent ability to produce esters. Studying the biosynthesis pathway of esters, CS2.42 has the best esterification ability, while CS2.53 has the advantage of alcoholysis ability. The exploration of the biosynthetic pathway of acetate and ethyl esters has laid a foundation for regulating esters in soy sauce fermentation.
Aroma profiles and aroma-active compounds of Sichuan vinegar that is one of the four-famous vinegars in China were systemically analyzed by SAFE-GC-MS and GC-O. In addition, descriptive profile analysis, aroma reconstitution, and omission test were used to evaluate and compare the Sichuan modern vinegar (SMV) and Sichuan traditional vinegar (STV). A total of 99 volatile compounds were tentatively identified from the neutral and acidic fractions of both samples. Among them, 77 compounds were positively identified after comparison with their corresponding standards. Forty-two aroma-active compounds were characterized with flavor dilution (FD) factors from 1 to 6561 by AEDA-GC-O, with the highest for 2-hydroxy-3-butanone, butyrolactone, furan-2-carbaldehyde, acetic acid, and 3-oxobutan-2-yl acetate in both STV and SMV samples. Among them ten were identified for the first time in vinegar. Moreover, 40 aroma-active compounds were quantitatively determined, and 26 compounds exhibited their odor activity values (OAVs) larger than 1. The reconstituted solutions showed similar aroma profiles with the original samples in their characteristic aromas in terms of fruity, sweet, roasty, spicy, and woody notes, but in slight differences in nutty and herbal notes.
The odour-active compounds of feijoa (Acca sellowiana), were isolated by Solvent-Assisted Flavour Evaporation (SAFE). By application of GC-O and the aroma extract dilution analysis (AEDA), nineteen odorants were detected. Volatile compounds with highest flavour dilution (FD) factor were quantified by internal standard and relative response factor. On the basis of the quantitative data and odour thresholds in water, odour activity values (OAV) were calculated. High OAVs were determined for ethyl butanoate, Z-3-hexenal, linalool and methyl benzoate responsible for the fruity, green, flowery and medicinal notes. A recombination assay and omission tests, showed the relevance of Z-3-hexenal, linalool and methyl benzoate as odour active compounds in feijoa aroma. Headspace solid-phase microextraction (HS-SPME) was used in order to verified linalool enantiomeric distribution in two feijoa varieties. R-linalool was the major configuration in both varieties. Quimba variety showed an enantiomeric ratio 75:25 while for Mammoth variety, linalool enantiomeric ratio was 95:5 (R:S).
The aroma profile of Semnostachya menglaensis Tsui (S. menglaensis) was identified by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). A total of 29 odor-active compounds, which have aroma intensities ranging from 0.2 ± 0.5 to 10.0 ± 0.0 were detected by GC-O, whereas 14 compounds were detected as important odorants by quantitative analysis and odor activity values (OAVs). An aroma recombination model prepared by mixing 12 odor-active compounds with OAVs ≥ 1 in an "aroma-free" S. menglaensis matrix showed good similarity to the aroma of original S. menglaensis. Omission tests showed that in the overall aroma of S. menglaensis, 2-propionyl-3,4,5,6-tetrahydropyridine, 2-propionyl-1-pyrroline, 1-octen-3-ol, and linalool were the key odorants, and 2-acetyl-3,4,5,6-tetrahydropyridine, 2-propionylpyridine, and α-ionone were also important.
The dominant aroma compounds in the breast skin and breast muscle of Beijing roasted duck were investigated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS), odor activity values and aroma recombination. The results demonstrated that a total of 42 aroma compounds were identified in Beijing roasted duck, including aldehydes, ketones, alcohols, acids, phenols, sulfur-containing compounds and nitrogen-containing compounds. Among the 42 aroma compounds, 18 were identified as important odorants with odor activity values (OAVs) greater than 1. Aroma recombination, omission experiments and sensory evaluation demonstrated that 9 aroma compounds significantly contributed to the characteristic aroma of Beijing roasted duck. These 9 key aroma compounds were 2-furfurylthiol, dimethyl trisulfide, hexanal, heptanal, octanal, nonanal, methional, 1-octen-3-ol and (E, E)-2,4-decadienal. Among these, 2-furfurylthiol (3620≤OAV≤31606) and dimethyl trisulfide (2515≤OAV≤23470) significantly contributed to the aroma of roasted duck (p <0.01). Sensory evaluation of the recombination model with 9 aroma compounds scored 4.5 out of 5 points. The major aroma profile of Beijing roasted duck included strong fatty, roasty and meaty aromas. The key aroma compounds of Beijing roasted duck were concluded to be 2-furfurylthiol, dimethyl trisulfide, hexanal, heptanal, octanal, nonanal, methional, 1-octen-3-ol and (E, E)-2,4-decadienal.
Although soy sauce is a globally used seasoning, its sensory properties have not been fully revealed. Here, the sensory characteristics of 149 soy sauces were examined using descriptive analyses. Eighty‐eight attributes were identified and integrated them into a flavor wheel. Aroma was the sensory modality described most often, suggesting that soy sauce's aroma is likely important in characterizing its sensory quality. Nineteen out of 88 attributes were found in all soy sauces implying their importance in representing a soy sauce‐like quality. These 19 attributes allowed the discrimination of manufacturing methods and the successful generation of a comparison map. Other attributes appeared infrequently, indicating that all soy sauces are unique and that these attributes can be utilized to describe subtle differences in their characters.
Practical application
Since soy sauce has become a globally used seasoning, it is meaningful to define its attributes for sensory evaluation. Establishing the sensory attributes of soy sauce allows us to describe each soy sauce objectively and share sensory perceptions among consumers, producers, and researchers. A flavor wheel would facilitate people's systematical understanding of the sensory characteristics of soy sauce. Also sensory evaluation using a flavor wheel would be helpful in finding previously unrecognized attractive or non‐attractive characteristics in soy sauces, which ultimately affects purchase decisions. Defining the minimum attributes required for creating a soy sauce positioning map would save a great deal of time and money for product development. Finally, knowledge about the relationship between sensory qualities and the manufacturing process and/or production area would be helpful in regards to product development and purchasing decisions.
Sensory wheels provide standardized vocabularies for product categories and thus enable better communication among sensory scientists, product developers and their business partners. Recently, increased interest in spices prompted the development of an updated dried spice and herb aroma wheel, the original of which was created at McCormick and Company, Inc. (McCormick) during the mid-1990s. The new version of the McCormick Spice Wheel (MSW) was generated from lexicons developed at McCormick, a sample of which were validated to still be appropriate through cluster analysis, principal component analysis and correlations. The final spice- wheel was validated by a team of sensory scientists (n = 5) including panel leaders (n = 3) and a group of trained descriptive panelists (n = 9). The final MSW has 17 categories and 56 attributes.
Lexicons allow sensory scientists to evaluate a product or product category with an organized, established vocabulary. Wheels are visual representations of these lexicons and offer a standardized vocabulary for sensory scientists and their business associates, particularly those in product development. Wheels can be useful in teaching descriptive panelists which attributes are related to each other. This can be useful in panel discussions in which there is dissension about the definition of a particular attribute. If panelists understand that two or more attributes are related in a wider perspective, then consensus flows more naturally. Additionally, wheels are helpful in business presentations in which sensory scientists must explain a conceptual sensory space or during benchtop evaluations in which sensory scientists must assist product developers in understanding the sensory properties of a food product.
The generation of aroma compounds and the changes in sensory characteristics through the soy sauce koji fermentation were investigated to evaluate the crucial impact of the koji fermentation on soy sauce aroma. The sensory analysis showed a marked increase in ‘musty’ and ‘soy sauce-like’ odours, whereas the beany attribute decreased significantly during koji fermentation. Aldehydes and alcohols were the major volatile classes present in the koji samples. Gas chromatography–olfactometry was used to identify the aroma-active compounds in harvested koji, and the results showed that 1-octen-3-ol, 3-octanol, (E)-2-octenal, di-epi-α-cedrene, benzeneacetaldehyde and 3-(methylthio)-propanal exhibited the greatest aroma intensities in harvest koji. Moreover, relative contents of (E)-2-octenal, benzeneacetaldehyde, 3-(methylthio)-propanal and 2-phenylpropenal were found to be positively related to ‘musty’ and ‘soy sauce-like’ odours. Results from principal component analysis showed that the growth and sporulation of Aspergillus oryzae had the important impacts on the volatile evolution.
Abstract
Twenty soy sauce products were presented to two sensory panels, one in Thailand and one in the U.S.A. Both panels had extensive training conducting descriptive sensory studies. Neither group had tested soy sauce previously; however, they had different familiarity with soy sauce. Each group separately evaluated samples during the same time period, then met in Thailand to compare and discuss their generated lexicons. Most attributes listed by each group of panelists provided similar definitions and references. Although, a few attributes were not used by one or the other panel because that term either does not exist in both languages (e.g., “cured” is not a term for the Thai panel), represented an uncommon characteristic (e.g., “roaches” for the American panel), or were complex concepts (e.g., “brown”), the panelists used references to assist their understanding of unclear attributes. After discussion, both panels agreed on 59 attributes with definitions and references for a soy sauce lexicon. The article presents attributes in English and Thai.
Practical Applications
A universal lexicon developed by different groups of trained panelists could reduce confusion and make the lexicon more understandable. A universal lexicon would help researchers in other countries to understand product quality. Additionally, the developed lexicon allows researchers to conduct studies with the same standard method in different laboratories enabling comparable results.
An investigation using the Aroma Extract Dilution Analysis (AEDA) technique of the aroma concentrate from a raw Japanese soy sauce and the heated soy sauce revealed 40 key aroma compounds including 7 newly identified compounds. Among them, 5(or 2)-Ethyl-4-hydroxy-2(or 5)-methyl-3(2H)-furanone and 3-hydroxy-4,5-dimethyl-2(5H)-furanone exhibited the highest FD factor of 2048, followed by 3-(methylthio)propanal, 4-ethyl-2-methoxyphenol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone as having the FD factors from 128-512 in the raw soy sauce. Furthermore, comparative AEDAs, a quantitative analysis, and a sensory analysis demonstrated that whereas most of the key aroma compounds in the raw soy sauce were common in the heated soy sauce, some of the Strecker aldehydes and 4-vinylphenols contributed less to the raw soy sauce aroma. The model decarboxylation reactions of the phenolic acids during heating of the raw soy sauce revealed that although all reactions resulted in low yields, the hydroxycinnamic acid derivatives were much more reactive than the hydroxybenzoic acid derivatives due to the stable reaction intermediates. Besides the quantitative analyses of the soy sauces, the estimation of the reaction yields of the phenolic compounds in the heated soy sauce revealed that although only the 4-vinylphenols increased during heating of the raw soy sauce, they might not mainly be formed as decarboxylation products from the corresponding hydroxycinnamic acids, but from the other proposed precursors, such as lignin, shakuchirin, and esters with arabinoxylan.
Considering the important influence of longtime (150 day) moromi fermentation and heat treatment on the aroma formation of
traditional Chinese-type soy sauce (TCSS), volatile compounds in samples taken from different stages of moromi fermentation
and heat treatment were analyzed by solid phase microextraction coupled with gas chromatography-mass spectrometry. Results
showed that a total of 76 volatile compounds were identified in all the samples, and most of the volatile compounds were common.
During 150 day of moromi fermentation, relative contents of acids, alcohols, aldehydes and ketones, esters, and furan(one)s
along with all the sensory attributes of acidic, alcoholic, fruity, caramel-like, smoky, and malty changed greatly. Notably,
relative contents of alcohols, aldehydes and ketones along with the sensory intensities of alcoholic, caramel-like, and smoky
of heated sample (80°C/60 min) decreased markedly, whereas there were slight increases in relative contents of furan(one)s,
phenols, and sulfur-containing compounds of it. Long-time moromi fermentation and heat treatment have significant influence
on the formation and relative contents of volatile compounds in TCSS, whereas changes in volatile compounds and their relative
contents of the samples were responsible for the differences in sensory attributes.
Keywordsvolatile compound-traditional Chinese-type soy sauce-gas chromatography-mass spectrometry-moromi fermentation-heat treatment
Aroma compounds in Chinese "Wuliangye" liquor were identified by gas chromatography-olfactometry (GC-O) after fractionation. A total of 132 odorants were detected by GC-O in Wuliangye liquor on DB-wax and DB-5 columns. Of these, 126 aromas were identified by GC-mass spectrometry (MS). Aroma extract dilution analysis (AEDA) was further employed to identify the most important aroma compounds in "Wuliangye" and "Jiannanchun" liquors. The results showed that esters could be the most important class, especially ethyl esters. Various alcohols, aldehydes, acetals, alkylpyrazines, furan derivatives, lactones, and sulfur-containing and phenolic compounds were also found to be important. On the basis of flavor dilution (FD) values, the most important aroma compounds in Wuliangye and Jiannanchun liquors could be ethyl butanoate, ethyl pentanoate, ethyl hexanoate, ethyl octanoate, butyl hexanoate, ethyl 3-methylbutanoate, hexanoic acid, and 1,1-diethoxy-3-methylbutane (FD > or = 1024). These compounds contributed to fruity, floral, and apple- and pineapple-like aromas with the exception of hexanoic acid, which imparts a sweaty note. Several pyrazines, including 2,5-dimethyl-3-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2,6-dimethylpyrazine, 2,3,5-trimethylpyrazine, and 3,5-dimethyl-2-pentylpyrazine, were identified in these two liquors. Although further quantitative analysis is required, it seems that most of these pyrazine compounds had higher FD values in Wuliangye than in Jiannanchun liquor, thus imparting stronger nutty, baked, and roasted notes in Wuliangye liquor.
Application of aroma extract dilution analysis (AEDA) to the volatiles isolated from a commercial Japanese soy sauce revealed 30 odor-active compounds in the flavor dilution (FD) factor range of 8-4096, among which 2-phenylethanol showed the highest FD factor of 4096, followed by 3-(methylsulfanyl)propanal (methional), the tautomers 4-hydroxy-5-ethyl-2-methyl- and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone (4-HEMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF), and 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolone), all showing FD factors of 1024. Thirteen odorants were quantified by stable isotope dilution assays, and their odor activity values (OAVs) were calculated as ratio of their concentrations and odor thresholds in water. Among them, 3-methylbutanal (malty), sotolone (seasoning-like), 4-HEMF (caramel-like), 2-methylbutanal (malty), methional (cooked potato), ethanol (alcoholic), and ethyl 2-methylpropanoate (fruity) showed the highest OAVs (>200). An aqueous model aroma mixture containing 13 odorants, which had been identified with the highest OAVs, in concentrations that occur in the soy sauce showed a good similarity with the overall aroma of the soy sauce itself. Heat treatment of the soy sauce resulted in a clear change of the overall aroma. Quantitation of selected odorants revealed a significant decrease in sotolone and, in particular, increases in 2-acetyl-1-pyrroline, 4-HDMF, and 4-HEMF induced by heating.
PLSR analysis and sensory evaluation of GC-MS result of phenolic compounds contribution to smoked flavor in Chinese bacon
- Hongwei
Microbial community structure and dynamic succession in traditional fermentation of Mucor-type Yongchuan Douchi
- Li
Changes in Aroma Components of Yongchuan Douchi during the Fermentation Process
- Suo
Characteristic flavour of Mucor-type and Aspergillus-type Douchi
- He
Changes of basal components and biogenic amines in the preparation of Yongchuan Douchi koji
- Hu
Quantitative Description Analysis of Flavor Characteristics of Special Flavored Horsebeans
- Li
Changes in Basal Components and Protease Activity at Different Stages of the Traditional Processing of Yongchuan Douchi
- Suo
GC-MS Analysis of Volatile Components in Mucor-fermented Soybean and Aspergillus-fermented Soybean
- Tang
Research progress on the production pathway of 3-methylbutanal in fermented sausage
- Ma
Changes in Total Sugar and Amino Acids, and Formation of Taste Compounds in Yongchuan Douchi during Fermentation
- Suo
Application of Flash Profile method in sensory evaluation of Douchi
- Yang