Fragrance Research Articles

Mechanistic insights into soy sauce flavor enhancement via Co-culture of Limosilactobacillus fermentum and Zygosaccharomyces rouxii

For years, the intricate interactions between microorganisms in fermented food have played a key role in enhancing flavor. Our previous study highlighted that co-culture of Limosilactobacillus fermentum (L. fermentum) and Zygosaccharomyces rouxii (Z. rouxii) could enhance the flavor improvement capability of Z. rouxii in soy sauce fermentation, but the mechanism has been understudied. In this study, gas chromatography-mass spectrometry (GC-MS), GC-MS combined with derivatization (Der-GC-MS) and metabolite addition experiments were employed to elucidate their interaction. The first reason for the enhanced flavor of co-culture was that L. fermentum itself could produce the caramel-like compounds, such as HDMF and 2-furanmethanol. Another important reason was the commensality interaction between L. fermentum and Z. rouxii, where L. fermentum not only grew vigorously, but also significantly promoted the growth of Z. rouxii, mitigating the inhibitory effects of acetic acid on Z. rouxii. Further validation revealed that the metabolites of L. fermentum could stimulate the reproduction of Z. rouxii and increase the synthesis of aroma compounds such as phenylethyl acetate and ethyl acetate. Notably, glycerin and lactic acid emerged as pivotal metabolites facilitating enhanced aroma production. This study offers valuable insights for advancing flavor regulation techniques in soy sauce production.

Comparison of Different Deodorizing Treatments on the Flavor of Paddy Field Carp, Analyzed by the E-Nose, E-Tongue and Gas Chromatography-Ion Mobility Spectrometry.

Changes in the flavor and taste profiles of Paddy Field Carp after deodorization with perilla juice (PJ), cooking wine (CW) and a mixture of the two (PJ-CW) were analyzed using the E-nose, E-tongue, gas chromatography-ion mobility spectrometry (GC-IMS), free amino acid analysis and taste nucleotide analysis. The E-nose and E-tongue revealed that deodorization reduced the content of sulfur-containing compounds, enhanced umami, bitterness, sourness and astringency, and decreased saltiness. PCA and OPLS-DA analysis successfully distinguished between the effects of the treatments. Free amino acids increased from 8777.67 to 11,125.98 mg/100 g and umami amino acids increased from 128.24 to 150.37 mg/100 g after PJ-CW deodorization (p < 0.05). Equivalent umami concentration (EUC) comparisons showed that PJ-CW treatment produced the greatest synergistic umami enhancement (to 3.15 g MSG equiv./100 g). GC-IMS detected 52 aroma compounds; PJ treatment produced the greatest diversity of aldehydes, including heptanal, nonanal, hexanal, 3-methylbutanal, (E)-2-heptenal and (E,E)-2,4-heptadienal. The total content of volatile flavor compounds was the highest after PJ-CW treatment, and the content of many characteristic flavor substances (3-hydroxy-2-butanone, benzaldehyde, 5-methyl-2(3H)-furanone) increased. These findings provided a theoretical basis for the further development of deodorization methods for Paddy Field Carp.

Mechanism of the interaction between olfactory receptors and characteristic aroma compounds in sweet orange juice

The aroma compounds of three varieties of orange juice were extracted using solvent-assisted flavor evaporation (SAFE) and stir bar sorptive extraction (SBSE). A total of 41 aroma compounds were identified by gas chromatography-olfactometry (GC-O), among which 10 aroma compounds had an aroma intensity (AI) > 4.5. There were 53 aroma compounds identified by gas chromatography-mass spectrometry (GC-MS), 29 of which had an odor activity value (OAV) higher than 1. The findings indicated that (+)-limonene, linalool, hexanal, citral and myrcene were closely associated with the five characteristic aromas of orange juice. Furthermore, molecular docking was used to analyze the binding energies and interactions between these compounds and olfactory receptors (OR1A1, OR1D2, OR2W1, OR5AC2, OR1A2, and OR5M3). The average binding energies for these compounds at the six receptors were −6.2 kcal/mol, −6.0 kcal/mol, −5.8 kcal/mol, −5.1 kcal/mol, −6.3 kcal/mol and −4.7 kcal/mol, respectively. Hydrophobic interaction was a significant driving force in this process. Key residues such as Leu199 (OR1D2), Ala108 (OR1A2), Gly108 (OR2W1), Pro181 (OR5M3), Tyr261 (OR5AC2), and Val203 (OR1A1) played key roles in binding with characteristic aroma compounds. The formation mechanism of orange juice aroma was revealed, which provides theoretical guidance for the regulation of sweet orange aroma and flavor.

Comparison and identification of aroma components in 21 kinds of frankincense with variety and region based on the odor intensity characteristic spectrum constructed by HS–SPME–GC–MS combined with E-nose

Frankincense is an important seasoning and spice known for its distinctive and intricate flavor profile. Considering the considerable variation in the aromatic quality of frankincense due to geographical origin, species diversity and cultivation conditions, frankincense from major global origins was characterized holistically for the first time. The electronic nose (E-nose) with headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) and sensory evaluation were implemented to characterize the aroma components of 21 commercial varieties of frankincense from around the world. The results showed that a total of 149 volatile organic compounds (VOCs) of 10 categories were identified in frankincense, among which the numbers of alcohols, terpenes and esters compounds accounted for 22.15 %, 18.79 % and 15.44 % of the total VOCs of frankincense, respectively. The PLS-DA model effectively distinguished frankincense from Oman/Somalia and other origins. Furthermore, the study identified two differential VOCs with VIP > 1 in three Asian countries and five in six African countries. The total VOCs content and sensory characteristic score of “Lemon/Citrus” in Oman frankincense is significantly higher than other regions. The OAV results showed that 61 substances (e.g., Diacety, alpha-Pinene, Camphene, Myrcene) as key aroma compounds and OICS model indicated that p-Cymenol was found to contribute significantly to the citrus aroma in frankincense. This study identified the fundamental components of frankincense flavor and revealed different flavor descriptors of frankincense, which are crucial for reconstructing frankincense flavor and improving flavor quality.

Effects of Different Fermentation Methods on Flavor Quality of Liupao Tea Using GC-Q-TOF-MS and Electronic Nose Analyses.

To further develop Liupao tea products and enhance their flavor, this study investigated the effects of different fermentation methods on the aroma quality of Liupao tea. The aroma quality of Liupao tea was comprehensively analyzed using HS-SPME in combination with GC-Q-TOF-MS, electronic nose, and sensory evaluations. Electronic nose detection showed that the aroma fingerprints of Liupao tea samples with different fermentation methods were different. Sulfides, alcohols, ketones, and methyls were the main aroma categories affecting the aroma of the four groups of Liupao tea samples. GC-Q-TOF-MS analysis revealed significant differences in the composition of aroma components among the four fermentation methods of Liupao tea (p < 0.05). Furthermore, the total amount of aroma compounds was found to be highest in the group subjected to hot fermentation combined with the inoculation of Monascus purpureus (DMl group). Based on the OPLS-DA model, candidate differential aroma components with VIP > 1 were identified, and characteristic aroma compounds were selected based on OAV > 10. The key characteristic aroma compounds shared by the four groups of samples were 1,2,3-Trimethoxybenzene with a stale aroma and nonanal with floral and fruity aromas. The best sensory evaluation results were obtained for the DMl group, and its key characteristic aroma compounds mainly included 1,2,3-Trimethoxybenzene, nonanal, and cedrol. The results of this study can guide the development of Liupao tea products and process optimization.

Advantages of UHT in retaining coconut milk aroma and insights into thermal changes of aroma compounds

Coconut milk products are susceptible to bacterial damage, necessitating sterilization methods that often compromise nutrient and aroma integrity. This study investigates the effects of different thermal sterilisation methods on coconut milk aroma using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). We assessed the impact of pasteurisation (PAS, 70 °C, 25 min), high-temperature sterilisation (HTS, 121.1 °C, 15 min), and ultra-high temperature sterilisation (UHT, 130 °C, 5 s) through clustered heat maps and correlation analyses. Significant differences were observed (p < 0.05), with 37 and 52 substances detected by HS-GC-IMS and HS-SPME-GC-MS, respectively, identifying 12 key aroma compounds. UHT treatment primarily reduced 8 acids, maintaining a compositional structure and sensory profile similar to raw coconut milk. PAS and HTS treatments decreased the sensory intensity of overall coconut milk aroma, creamy, and floral notes, correlating with the presence of 2-heptanol, nonanal, 4-methylvaleric acid, and 2-tridecanone. These methods increased cooked notes, associated with 5-methyl-3-heptanone, 3-butyn-1-ol, hydroxyacetone, and acetoin. Rancidity was linked to acids such as isobutyric acid, isovaleric acid, and heptanoic acid, with high temperatures effectively reducing these compounds. Prolonged temperature changes in PAS and HTS accelerated lipid oxidative degradation and the Maillard reaction, involving free fatty acids in the formation of alcohols, aldehydes, esters, and lactones. These findings provide a theoretical basis for studying coconut milk flavour deterioration.

Potential of Endophytic Microorganisms in Fermentative Processes Using Agro-Industrial Waste as Substrates

This study investigated the potential of endophytic microorganisms in fermentative processes using agro-industrial residues as substrates. The aim was to explore sustainable biotechnological methods for producing valuable compounds from waste. Endophytic microorganisms were isolated from strawberry, lychee, and tangerine and used in fermentative processes with passion fruit, guava, and pineapple residues. Key methods included isolating and screening potent aroma-producing microorganisms, identifying them using MALDI-TOF MS, and analyzing volatile compounds by GC-MS. The results identified 37 endophytic microorganisms, with Kloeckera apiculata presenting the greatest aromatic potential. Fermentation with agro-industrial residues produced significant volatile compounds, identifying 27, 23, and 22 compounds from passion fruit, pineapple, and guava residues, respectively. The main conclusions highlighted the high production of ethyl acetate and 2-phenylethyl acetate, which contributed to fruity and floral aromas. The novelty of this study lies in the use of endophytic microorganisms isolated from tropical fruits to biotransform agro-industrial waste into high-value aromatic compounds, offering economic and environmental benefits. This research is significant, as it proposes a sustainable approach to valorize waste and produce natural aroma compounds through biotechnological processes.

Innovative insights into the roasting-driven transformation of volatile compounds and quality markers in flaxseed (Linum usitatissimum L.) oil.

Roasting is essential for developing the characteristic aroma of flaxseed oil (FSO), yet its impact on oil quality remains underexplored. This study employed headspace-gas chromatography-mass spectrometry coupled with multivariate analysis to elucidate the dynamic changes in volatile compounds and quality characteristics of FSO subjected to varying roasting temperatures. Our findings revealed that seven key aroma compounds, identified through the variable importance in the projection scores of partial least square-discrimination analysis models and relative aroma activity value, served as molecular markers indicative of distinct roasting temperatures. These compounds included 2,5-dimethylpyrazine, 2-pentylfuran, (E)-2-pentenal, 2-ethyl-3,6-dimethylpyrazine, heptanal, octanal, and 2-hexenal. Notably, roasting at 200°C was found to enhance oil stability and antioxidant capacity, with phenolic compounds and Maillard reaction products playing synergistic roles in bolstering these qualities. Network analysis further uncovered significant correlations between these key aroma compounds and quality characteristics, offering novel perspectives for assessing FSO quality under diverse roasting conditions. This research not only enriched our understanding of the roasting process's impact on FSO but also provided valuable guidance for the optimization of industrial roasting practices. This study would provide important practical applications in aroma regulation and process optimization of flaxseed oil. .

Discriminative analysis of aroma profiles in diverse cigar products varieties through integrated sensory evaluation, GC-IMS and E-nose

Cigars, treasured for their rich aromatic profiles, occupy a notable segment in the global consumer market. The objective of this study was to characterize the volatile aroma compounds that shape the flavor profiles of six distinct varieties of Great Wall cigars, contributing to the understanding of cigar aroma analysis. Utilizing HS-GC-IMS and sensory evaluation, the study discerned the aroma profiles of GJ No. 6 (GJ), Animal from the Chinese zodiac (SX), Range Rover No. 3 Classic (JD), Miracle 132 (QJ), Sheng Shi No. 5 (SS), and Red 132 (HS) cigars. The analysis uncovered a spectrum of characteristic aromas, including tobacco, creaminess, cocoa, leather, baking, herbaceous, leathery, woodsy, and fruity notes. A total of 88 compounds were identified, categorized into 11 chemical classes, with their quantities varying among the cigars in a descending order of QJ, JD, GJ, SS, HS, and SX. 24 compounds, such as 2-heptanone, n-butanol, 2,6-dimethylpyrazine and 2-furfuryl methyl sulfide were considered as key differential components. The volatile components were effectively differentiated using principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and cluster analysis, revealing correlations between sensory attributes, key components, and electronic nose (E-nose). This research introduces a novel method for analyzing volatile aroma components in cigars, offering insights to enhance cigar quality and to foster the development of new products with unique aroma profiles.

Characterization of the key differential aroma compounds in five dark teas from different geographical regions integrating GC–MS, ROAV and chemometrics approaches

Dark tea (DT) holds a rich cultural history in China and has gained sizeable consumers due to its unique flavor and potential health benefits. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS), relative odor activity value (ROAV), and chemometrics approaches were used to detect and analyze aroma compounds differences among five dark teas from different geographical regions. The results revealed that the five DTs from different geographical regions differed in types, quantities, and relative concentrations of volatile compounds. A total of 1372 volatile compounds of were identified in the 56 DT samples by HS-SPME-GC–MS. Using ROAV and chemometrics approaches, based on ROAV>1 and VIP>1. Eighteen key aroma compounds can be used as potential indicators for DT classification, including dihydroactinidiolide, linalool, 1,2,3-trimethoxybenzene, geranyl acetone, 1,2,4-trimethoxybenzene, cedrol, 3,7-dimethyl-1,5,7-octatrien-3-ol, β-ionone, 4-ethyl-1,2-dimethoxybenzene, methyl salicylate, α-ionone, geraniol, linalool oxide I, linalool oxide II, 6-methyl-5-hepten-2-one, α-terpineol, 1,2,3-trimethoxy-5-methylbenzene, and 1,2-dimethoxybenzene. These compounds provide a certain theoretical basis for distinguishing the differences in five DTs from different geographical regions. This study provides a potential method for identifying the volatile substances in DTs and elucidating the differences in key aroma compounds.Abbreviations: DT, dark tea; FZT, Fuzhuan tea; LPT, Guangxi Liupao tea; QZT, Hubei Qingzhuan tea; TBT, Sichuan Tibetan tea; PET, Yunnan Pu-erh tea; ROAV, Relative odor activity value; OT, Odor threshold; HS-SPME, Headspace solid-phase microextraction; GC–MS, Gas chromatography-mass spectrometry; PCA, Principal components analysis; PLS-DA, Partial least squares-discriminant analysis; HCA, Hierarchical clustering analysis.

Unraveling the mechanism of aroma loss during prolonged hot air drying of non-smoked bacon: Insights into aroma compounds generation and retention

In this study, the potential mechanism of aroma loss in non-smoked bacon due to excessive hot air drying (beyond 24 h) was investigated, focusing on protein conformational changes and the inhibition of heme protein-mediated lipid oxidation by oleic acid. The results showed that prolonged hot-air drying caused a stretching of the myofibrillar protein (MP) conformation in bacon before 36 h, leading to an increase in reactive sulfhydryl groups, surface hydrophobicity, and the exposure of additional hydrophobic sites. Consequently, the binding ability of MP to the eight key aroma compounds (hexanal, 1-octen-3-ol, (E)-2-nonenal, 3-methyl-butanoic acid, 2-undecenal, (E, E)-2,4-decadienal, 2,3-octanedione, and dihydro-5-pentyl-2(3H)-furanone) was enhanced, resulting in their retention. On the other hand, a sustained increase in oleic acid levels has been demonstrated to effectively inhibit heme protein-mediated lipid oxidation and the formation of these key aroma compounds. Using lipidomic techniques, 30 lipid molecules were identified as potential precursors of oleic acid during the bacon drying process. Among these precursors, triglycerides (16:0/18:0/18:1) may be the most significant.

Yeast extracts weakened warmed-over flavor in surimi gels made from silver carp due to the masking effect by high concentrations of pyrazines and esters.

Warmed-over flavor (WOF) is an off-flavor in surimi gels. Yeast extract (YE) could improve the aroma properties of food. However, the effect of YE on the WOF in surimi gels and its mechanism was still unclear. In this study, aroma profiles, the composition of aroma compounds and aroma precursors, concentrations of WOF compounds, and thiobarbituric acid reactive substances (TBARS) of surimi gels with different amounts of YE were investigated by molecular sensory science and chromatographic techniques. Moreover, the effect of pyrazines and esters introduced by YE on WOF was also tested by sensory analysis. The addition of no less than 1% YE to surimi gels significantly weakened WOF. However, YE did not decrease the concentrations of WOF compounds and did not change the fatty acid composition and TBARS in surimi gels. Conversely, the addition of YE significantly increased the contents of free amino acids, N-containing compounds, and esters in surimi gels. The contents of total free amino acids, 2,6-dimethylpyrazine, and ethyl acetate in surimi gels with 2.5% YE were 1.5, 21, and 2.1 times higher than those in the control, respectively. Additionally, the sensory results of the spiked aroma models containing WOF compounds, 2,6-dimethylpyrazine, and esters showed that more than 9.4µg/kg of 2,6-dimethylpyrazine with a baked-potato note and more than 6.1µg/kg of ethyl acetate and 11.2µg/kg of butyl acetate with a fruity note could significantly mask WOF. In conclusion, WOF in surimi gels could be masked by YE due to the high concentrations of pyrazines and esters. Practical Application: Yeast extracts could decrease the warmed-over flavor (WOF) due to the high concentrations of pyrazines (baked-potato note) and esters (fruity note). This finding extends the application of yeast extracts in the food industry. On the other hand, this study presents a reasonable solution for the reduction of WOF in surimi products.

Variation in the Aroma Composition of Jasmine Tea with Storage Duration.

This study investigated the changes in the aroma of jasmine tea during storage. Solid-phase micro-extraction (SPME)-gas chromatography (GC)-mass spectrometry (MS) and stir bar sorptive extraction (SBSE)-GC-MS were combined to detect all volatile compounds. GC-olfactometry (GC-O), odor activity value (OAV), and p-value were employed to analyze and identify the key aroma compounds in six jasmine tea samples stored for different durations. Nine key aroma compounds were discovered, namely (Z)-3-hexen-1-yl acetate, methyl anthranilate, methyl salicylate, trans-β-ionone, linalool, geraniol, (Z)-4-heptenal, benzoic acid methyl ester, and benzoic acid ethyl ester. The importance of these compounds was confirmed through the aroma addition experiment. Correlation analysis showed that (Z)-4-heptenal might be the main reason for the increase in the stale aroma of jasmine tea. Through sensory evaluation and specific experimental analysis, it can be concluded that jasmine tea had the best aroma after 3 years of storage, and too long a storage time may cause the overall aroma of the tea to weaken and produce an undesirable odor. The findings can provide a reference for the change in aroma during the storage of jasmine tea and provide the best storage time (3 years) in terms of jasmine tea aroma.

Identification of volatile and odor-active compounds in Maojian herbal tea (Dracocephalum rupestre Hance)

Maojian herbal tea originates from Xinzhou, Shanxi, China, and is renowned as one of the prominent northern Chinese herbal teas. However, the volatile and key odor-active compounds in Maojian herbal tea have not been reported. Using headspace-solid-phase microextraction coupled with gas chromatography–mass spectrometry, a total of 87 volatile compounds were identified. Thirteen aroma compounds were distinguished as the key odor-active compounds of Maojian herbal tea based on gas chromatography–olfactometry analysis, and odor activity values, including trans-β-ionone, cis-jasmone, β-caryophyllene, humulene, hexanal, nonanal, linalool, alloocimene B, β-cyclocitral, β-bourbonene, ylangene, δ-cadinene and indole. The results of partial least squares regression analysis demonstrate strong correlations between the odor-active compounds and odor properties. β-Caryophyllene is the main contributor to the woody aroma of Maojian herbal tea. The results of the present study offer a scientific insight into the aroma profile of Maojian herbal tea.

Identification of characteristic compounds of sweet orange oil and their sweetening effects on the sucrose solution with sweetness meter, sensory analysis, electronic tongue, and molecular dynamics simulation

The characteristic aroma compounds of five-fold sweet orange oil were analyzed using gas chromatography–mass spectrometry combined with the odor aroma value (OAV) method. The results indicated that limonene, linalool, dodecanol, (E,E)-2,4-decadienal, (E)-citral, linalool, (E)-2-decenal, and geraniol are important contributors. The sweetening effects of key compounds on sucrose solutions were experimentally investigated. The results showed that the sweetness effects of five compounds (limonene, citronellal, geraniol, β-sinensal and β-caryophyllene) were better than those of (E)-citral, linalool and octanal. Molecular dynamics implied that the hydrogen bonding residues of the T1R2/T1R3-sucrose system were converted from LYS65, GLU302, ASP278, and SER144 to ASP278, SER144, ASP142, and ASP213 after the addition of limonene. Meanwhile, the hydrophobic interaction forces of the system are significantly enhanced. The total energy of the T1R2/T1R3-sucrose system decreased from −32.08 kcal/mol to −63.57 kcal/mol. The synergistic sweetening mechanism of characteristic aroma compounds of sweet orange oil on sucrose was revealed.

Metabolomic analysis of grapes and leaves from symptomatic and asymptomatic Vitis vinifera grapevines with Esca disease

Esca is a grapevine trunk disease spreading in vineyards worldwide, and of rising concern since no efficient treatment is available to mitigate its impact. Trunks, grapes and leaves from symptomatic and asymptomatic Aragonês vines were collected at harvest stage to characterise plant responses associated with this fungal disease. Presence of Esca associated fungi in the trunks was confirmed by molecular methods using ITS region. Metabolomics of grapes and leaves was analysed by Gas chromatography coupled to electron impact ionization time-of-flight mass spectrometry (GC-EI/TOF-MS) and GC coupled to an EI/quadrupole MS (GC-EI/QUAD-MS and showed that both organs from symptomatic plants exhibited a different metabolic reprogramming than those from asymptomatic. Symptomatic leaves present lesser content in tricarboxylic and polyhydroxy acids, and this metabolic adjustment may involve salicylic acid metabolism. On the other hand, symptomatic fruits accumulate long-chain fatty acids probably related with cuticle reinforcement to mitigate changes in water transport caused by trunk damage, and defence-related metabolites such as α-tocopherol. Symptomatic berries also presented alterations in volatile aroma compounds such as C6-volatiles, and acetic acid suggesting an impact on subsequent wine quality. Altogether this study, identified putative metabolic markers associated with Esca disease in plants with different symptomatology and contributed to a physiological understanding of this fungal disease that could help in the development of mitigation strategies for its spread.

ABIOTIC STRESS GENE 1 mediates aroma volatiles accumulation by activating MdLOX1a in apple.

Fruit aroma is an important organoleptic quality, which influences consumer preference and market competitiveness. Aroma compound synthesis pathways in plants have been widely identified, among the lipoxygenase pathway is crucial for fatty acid catabolism to form esters in apple. However, the regulatory mechanism of this pathway remains elusive. In this study, linear regression analysis and transgene verification revealed that the lipoxygenase MdLOX1a is involved in ester biosynthesis. Yeast one-hybrid library screening indicated that a protein, MdASG1 (ABIOTIC STRESS GENE 1), was a positive regulator of MdLOX1a and ester production based on yeast one-hybrid and dual-luciferase assays, as well as correlation analysis among eight different apple cultivars. Overexpression of MdASG1 in apple and tomato stimulated the lipoxygenase pathway and increased the fatty acid-derived volatile content, whereas the latter was decreased by MdASG1 silencing and CRISPR/Cas9 knockout. Furthermore, MdASG1 overexpression enhanced the salt-stress tolerance of tomato and apple 'Orin' calli accompanied by a higher content of fatty acid-derived volatiles compared to that of non-stressed transgenic tomato fruit, while MdASG1-Cas9 knockdown calli do not respond to salt stress and promote the biosynthesis of fatty acid-derived volatiles. Collectively, these findings indicate that MdASG1 activates MdLOX1a expression and participates in the lipoxygenase pathway, subsequently increasing the accumulation of aroma compounds, especially under moderate salt stress treatment. The results also provide insight into the theory for improving fruit aroma quality in adversity.

Effects of Wickerhamomyces anomalus Co-Fermented with Saccharomyces cerevisiae on Volatile Flavor Profiles during Steamed Bread Making Using Electronic Nose and HS-SPME-GC-MS.

Steamed bread is a traditional staple food in China, and it has gradually become loved by people all over the world because of its healthy production methods. With the improvement in people's living standards, the light flavor of steamed bread fermented by single yeast cannot meet people's needs. Multi-strain co-fermentation is a feasible way to improve the flavor of steamed bread. Here, the dynamic change profiles of volatile substances in steamed bread co-fermented by Saccharomyces cerevisiae SQJ20 and Wickerhamomyces anomalus GZJ2 were analyzed using the electronic nose (E-nose) and headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The five detectors of the E-nose rapidly detected the changes in volatile substances in different dough or steamed bread with the highest response value in co-fermented dough. A total of 236 volatile substances were detected in all the samples using HS-SPME-GC-MS, and alcohols were the most variable component, especially Phenylethyl alcohol. Significantly, more alcohols and esters were upregulated in co-fermented dough, and the addition of W. anomalus GZJ2 improved the key volatile aroma compounds of steamed bread using the relative odor activity value method (ROAV), especially the aldehydes and alcohols. Moreover, these key volatile aroma compounds can be quickly distinguished using the W2S detector of the E-nose, which can be used for the rapid detection of aroma components in steamed bread.

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

Analysis of aroma compounds in different grades of Luzhou Laojiao strong-aroma Baijiu by molecular sensory science

Strong-aroma Baijiu is a beloved drink in China because of its elegant cellar aroma, sweetness and mellow taste, and its sales account for more than half of the Baijiu production. In this study, three different grades of strong-aroma Baijiu were analyzed systematically using comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry coupled with molecular sensory science. A total of 342 aroma compounds were identified in the three samples, including 152 aroma-active compounds. Principal component analysis revealed that higher-grade Baijiu contained more terpenes, acetals, and esters. In contrast, lower-grade Baijiu contained fewer esters and many compounds likely generated by the Maillard reaction, such as 5-methylfurfural, 2-propanoylfuran, 2,6-dimethylpyrazine, and 5-ethyl-2(5H)-furanone. Most of the aroma attributes of Baijiu samples could be simulated through aroma recombination experiments, but there were still some slight differences in individual aromas. Finally, the key aroma compounds of the three different grades of Baijiu were revealed through omission experiments. This study provided a scientific basis for the classification of strong-aroma Baijiu quality grades, thereby contributing to the high-quality development of the Baijiu industry.