Flavor Formation Research Articles

Flavor formation mechanisms based on phospholipid fermentation simulation system in oyster juice co-fermented by Lactiplantibacillus plantarum and Saccharomyces cerevisiae.

Oyster juice was co-fermented with Lactiplantibacillus plantarum 3-B and Saccharomyces cerevisiae 7-C, and the quality of the oyster juice and the relationships between phospholipids and flavor formation were investigated. The olfactory odor intensities of (E,E)-2,4-heptadienal and (E,Z)-2,6-nonadienal, which impart off-flavors, were reduced in the co-fermented oyster juice in comparison with the unfermented juice. Co-fermentation resulted in an increase of 5.34% in docosahexaenoic acid and 20.22% in eicosapentaenoic acid. The flavor formation mechanisms were explored using a phospholipid-based fermentation simulation system. The levels of the differential phospholipids lysophosphatidylcholine 15:0, lysophosphatidylcholine 16:0, and phosphatidylethanolamine 20:0/16:0 in the co-fermented system decreased by 25.13μg/mL, 6.87μg/mL, and 0.30μg/mL, respectively. Hexanal, (E,E)-2,4-heptadienal, and (E)-2-octenal were not detected in the co-fermented system. This study provides a novel approach to the processing of oyster juice and examines the phospholipid-related pathways involved in flavor formation.

The processing of shaking and standing improves the taste quality of summer black tea.

Shaking and standing (SS) enhances the aroma intensity and quality of black tea (BT). However, its contribution to the taste remains unknown, and the interaction mechanism between the aroma and taste perception of black tea is also undisclosed. Here, the metabolomics and sensory evaluation-assisted flavor analysis were employed to investigate the changes in non-volatiles induced by SS, and the interaction mechanism between aroma and taste perception. SSBT exhibited considerable reduced bitterness and astringency intensities compared to BT. Notably, the concentrations of contributing compounds such as catechins, proanthocyanidins, theaflavins, anthocyanins, and flavonol glycosides were decreased in SSBT. Sensory experiments further revealed that nine floral and sweet odorants in SSBT exhibited odor-enhancing interactions. Molecular docking validated the binding affinity and interaction forces between mono/di-ligands and OR1G1/OR52D1. Furthermore, the presence of the nine odorants exerted inhibitory effects on the bitterness and astringency of SSBT. These findings provide a novel perspective on the formation of flavor in SSBT.

Lipid nutritional variances in thermal-treated egg yolks and their influence on flavor formation

Lipid nutritional variances in thermal-treated egg yolks and their influence on flavor formation

Effect of microbial community on the formation of flavor components in cigar tobacco leaves during air-curing

BackgroundThe air-curing process of cigar tobacco leaves is typically conducted in an open environment, involving the participation of various microorganisms. However, the effect of microbial communities during air-curing process on the formation of flavor components remains unclear. Therefore, this study aims to reveal the dynamics of flavor components and microbial community changes, and explore the potential role of microbial communities in flavor formation during the cigar tobacco air-curing process.ResultsHigh-throughput sequencing analysis showed that Pantoea, Sphingomonas and Pseudomonas were the dominant bacterial genera during air-curing process, while Aspergillus was the dominant fungal genus. Subsequently, volatile flavor analysis shows that alkaloids were the most important volatile compounds in cigar leaves, followed by esters, alcohols and aldehydes. Furthermore, 38 characteristic volatile flavor compounds at different periods of air-curing were identified based on PLS-DA in different periods of air-curing. The correlation analysis between microorganisms and flavor components showed that Pantoea and Staphylococcus might promote the flavor formation from browning to post-air-curing and were positively correlated with specific flavor components like phenylacetaldehyde and acetophenone. Phoma, Mycosphaerella, Wallemia, and Cladosporium were identified as key fungal genera influencing flavor formation, as they showed positive correlations with multiple flavor components. These information enrich our understanding of the flavor formation of cigar tobacco during air curing.ConclusionsThere is a complex correlation between the microbial community and the flavor components, which may have a great influence on the flavor formation during the air-curing process of cigar leaves. Bacterial communities have higher species diversity and richness during air-curing, and have more complex correlation characteristics with volatile flavor, which may play more roles in the flavor formation. This study revealed the potential role of microbial community on flavor formation in cigar tobacco air-curing process, and provided guidance for subsequent screening of specific functional microorganisms to improve and stabilize cigar tobacco flavor.

Analysis and Comparison of Lipids in Monascus-Fermented Cheese from Different Ripening Periods Based on UHPLC-QTRAP MS Quantitative Lipidomics.

Monascus-fermented cheese (MC) is a new cheese product that undergoes a multistrain fermentation process, which results in unique flavor qualities. Lipid metabolism plays an important role in the flavor formation of MC. To clarify the lipid composition of MC and the changes in lipid composition at four ripening periods, this study resolved the lipid profiles of MC by using UHPLC-QTRAP MS. The results identified 21 lipid classes and 748 lipid species, 72 of which were significantly different (VIP > 1, p < 0.01, |log 2FC| > 1). Additionally, 83 relevant metabolic pathways were enriched. Based on the enriched metabolic pathways and lipid changes, the pathways of differential lipid formation in MC were mapped. The results of this study comprehensively characterize the changes in lipids during the ripening process of MC, which can be used in the future to deeply analyze the mechanism of flavor formation in MC.

Unlocking the chemical basis of fermented golden pompano (Trachinotus ovatus) inoculated with indigenous Bacillus subtilis: Focus on the role of lipid oxidation on volatile flavor formation.

Fermented golden pompano is a traditional food valued for its distinctive flavor profile, largely influenced by lipid oxidation. This study evaluated the role of local Bacillus subtilis SCSMX-2 strain in regulating lipid oxidation and improving the flavor profile of the fermented golden pompano. Untargeted metabolomics was used to identify 206 differential metabolites, predominantly lipids, amino acids, and peptides. Enrichment analysis revealed glycerophospholipid metabolism as a key lipid pathway. SCSMX-2 induced moderate lipid oxidation, significantly increasing free fatty acid content, especially omega-3 polyunsaturates. Characterization of 148 volatile compounds revealed a notable increase in lipid oxidation-derived flavor compounds, with 11, including seven lipid derivatives, emerging as distinctive. Correlation analysis showed that secondary lipid oxidation products, such as sn-glycero-3-phosphoethanolamine and lysophosphatidylcholine, are precursors to key flavor compounds. These findings provide a scientific basis for the targeted regulation of flavors in traditional fermented fish.

Microbial community of Nongxiangxing daqu during storage: microbial succession, assembly mechanisms and metabolic functions.

The storage process of Nongxiangxing daqu is closely related to the quality of the daqu. The role of storage in daqu manufacture remains unclear, and most actual production relies on previous production experience. With the extension of daqu storage over a period of time, saccharifying activity, liquefying activity, fermenting activity, and esterifying activity reached a peak when stored for 3 to 4 months. Analysis of the flavor compounds showed that 87 flavor components were detected in daqu, and esters and alcohols were the main flavor compounds found. Microbial community analysis suggested that Weissella was the dominant bacterial genus with relative abundance increasing during storage, while Thermomyces was dominant fungal genus with abundance decreasing during storage. Analysis of assembly processes revealed that bacterial assembly was primarily influenced by stochastic processes during storage, whereas fungal assembly was predominantly shaped by deterministic processes. The interactions among microbiota, flavor compounds, and physicochemical parameters were elucidated, suggesting that saccharifying activity was positively correlated with Weissella, Lactobacillus, Kodamaea and Wickerhamomyces, and most of esters were positively correlated with Pediococcus and Clavispora. Microbial community functions were also predicted, highlighting enzymes involved in carbohydrate degradation, flavor formation, and ethanol fermentation. Finally, simulated baijiu fermentation was performed by adding daqu stored for different times, and the results showed that daqu stored for 3 to 4 months was appropriate for baijiu brewing. The results presented in this study may enhance understanding of the impact of storage on daqu quality and, consequently, help to improve it. © 2025 Society of Chemical Industry.

Technological aspects of lactic acid bacteria originated from artisanal cheeses

Well-characterized, genetically stable starter cultures are used to produce safe fermented dairy products of consistent quality. Lactic acid bacteria play several roles in cheese production. The lactic acid produced influences the firmness of the curd, the yield, and the rheological properties of the cheese. Starter cultures contribute to the formation of flavour and aroma compounds in the product. The aim of the research is to select and determine the technological aspects of lactic acid bacteria isolated from fresh traditional cheese varieties, which could potentially be used as cheese starter. The 13 strains of the more than 50 lactic acid bacteria studied showed different proteolytic activities and moderate acidifier capacity, contributed to the suppression of pathogenic or spoilage bacteria, and, with cell autolysis, accelerated cheese ripening through the release of enzyme. There are species that convert non-carbohydrate compounds into aroma compounds such as diacetyl. The identified bacteria are Lactiplantibacillus pentosus Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Lactiplantibacillus argentoratensis. Based on the results, we can confirm that some of the lactic acid bacteria isolated from fresh cow and goat milk cheese can be potentially applied as starter cultures in cheese production such as Lacticaseibacillus paracasei L13C, Lactiplantibacillus pentosus L10G, Lactiplantibacillus plantarum L7C, and Lactiplantibacillus argentoratensis L2C.

Enhancing fermented vegetable flavor with Lactobacillus plantarum and Rhodotorula mucilaginosa

The formation of flavor in fermented vegetables is directly associated with the interactions among the resident microbial strains. This study explored the cooperative dynamics between Lactobacillus plantarum and Rhodotorula mucilaginosa in a simulated cabbage juice system. The obtained results indicated that the co-cultivation of these strains accelerated fermentation kinetics and enhanced lactic acid production. The strains achieved a balanced consumption of substrates within the co-fermentation system through the exchange of metabolites. Additionally, co-fermentation facilitated the synthesis of characteristic flavor compounds while reducing the levels of undesirable flavors. Growth monitoring and transcriptomic analysis revealed that L. plantarum, as the dominant strain, perceived the surrounding environment through quorum sensing signals and upregulated genes related to the synthesizing of key compounds, enhancing product yields and forming biofilms to adapt to the symbiotic environment. Conversely, R. mucilaginosa responded to the stress induced by L. plantarum via upregulating transporters of metabolites, genes related to antioxidant stress, and longevity regulating, ultimately achieving coexistence with L. plantarum. This research provides a comprehensive understanding of the interplay between microbial strains in modulating fermentation processes and flavor profiles in vegetable fermentation.

Accelerating maturation of Chinese rice wine by using a 20 L scale multi-sweeping-frequency mode ultrasonic reactor and its mechanism exploration.

The formation of flavor in traditional Chinese rice wine requires a long aging process. To accelerate the maturation of rice wine, a 20 L scale multi-sweeping- frequency mode ultrasonic reactor was employed in this study to explore the promoting effects. Rice wines were subjected under 10 combined types of sonication treatments with 20/28/40 kHz in single/double/triple frequencies, and in fixed or sweeping modes, respectively. Then samples were aged in room temperature for up to 180days. A 7.3% increase of total esters content was observed in rice wine sample after treated by a fixed 40kHz ultrasonication with 50W/L intensity at 30°C for 15min, compared with the untreated sample. After sonication and stored for six months, 286.78% increase of the volatile esters was found, compared to rice wine without ultrasoinc treatment and stored at same condition for same time. And the total volatile alcohol substances and total volatile aldehydes in rice wine decreased by 12.95% and 67.46%, while the total volatile acids increased by 17.11%, respectively. The research results also demonstrated that ultrasonic induced free radicals accounted for the variations of rice wine properties. And the correlation between the acoustic cavitation and the flavor formation was also observed.

Effects of interactions between microorganisms and lipids on inferior volatile compound production during cold storage of grouper (Epinephelus coioides).

The interaction between microorganisms, proteins, and lipids plays a critical role in the odor production of fish. To explore the specific impact of the interaction between lipids and microorganisms on the overall odor of grouper, this study excluded the influence of proteins and assessed lipid (POV and TBARS) and microbial characteristics (biofilm mass and ATP content) in lipid solutions. The Results showed that microbial growth and lipid oxidation mutually promote each other. Lipidomics analysis identified 44 differential lipids, and microbial diversity analysis pinpointed five key microorganisms (Carnobacterium, Pseudomonas, Gluconacetobacter, Vagococcus, and Shewanella). Furthermore, 20 key volatile compounds (VOCs) related to odor changes in the grouper lipid solution were identified using HS-SPME-GC-MS. Correlation network analysis revealed potential microbial and lipid contributions to VOC categories, including alcohols, aldehydes, ketones, and nitrogen- and sulfur-containing compounds. This study provides new insights into the roles of microorganisms and lipids in flavor formation, offering valuable knowledge for improving seafood quality control.

Unraveling the microbial community and succession during the maturation of Chinese cereal vinegar Daqu and their relationships with flavor formation

Unraveling the microbial community and succession during the maturation of Chinese cereal vinegar Daqu and their relationships with flavor formation

A new insight into the formation of special flavor during the drying process of boletes based on FTIR joint HS-SPME-GC-MS

A new insight into the formation of special flavor during the drying process of boletes based on FTIR joint HS-SPME-GC-MS

Maillard reaction inducing amino acids degradation can adjust the flavour characteristic of black tea.

Drying is the step that is to be used to adjust and control the formation of flavour and quality in black tea processing. In the present work, the comprehensive two-dimensional gas chromatography with mass spectrometry (GC×GC-MS) and gas chromatography olfactometry with mass (GC-O-MS) were used to determine the dynamic change of the volatile compounds in black tea during drying at 90, 120, 150°C for 1h. Results showed that the ratio of esters and aldehydes largely declined when temperature was elevated from 90°C to 150°C, while the ratio of heterocycles was increased to 22.4% from 16.5%. A total of 15 key aroma activity volatiles were screened out in three temperature dried samples, therein 11 volatiles were connected with the Maillard reaction, meaning these volatiles were highly relevant to the degradation of amino acids during the drying process. We detected that 21 amino acids were decreased with enhanced temperature and extended the drying time, which promoted the Maillard-derived volatiles formation. Therefore, it was suggested that to control the degradation of amino acids adjust the flavour profiles of black tea by changing the drying temperature and time.

Initial abiotic factors as key drivers in core microbe assembly: Regulatory effects on flavor profiles in light-flavor baijiu

Instability in initial abiotic factors of open solid-state fermentation systems can significantly alter Baijiu's flavor profile, but the mechanisms governing microbial interactions and flavor formation remain unclear. This study comprehensively monitored changes in abiotic factors, microbial communities, and flavor profiles across two distinct fermentation processes in a Baijiu distillery, which differed significantly in their management of initial abiotic factors. Our results revealed significant differences in abiotic factors between the two groups, including moisture, ethanol, acidity, glucose, and organic acid levels. The assembly of microbial communities in fermented grains was primarily driven by deterministic processes. The moisture content in the fermentation grains positively affected the growth and metabolism of core microbiota. The rapid proliferation and metabolism of core microbes led to a rapid increase in the acidity of the fermented grains, alongside a significant accumulation of ethyl lactate. This study provides technical support and theoretical guidance for Baijiu production.

Relationship between physicochemical properties, non-volatile substances, and microbial diversity during the processing of dry-cured Spanish mackerel.

To meet the demand of consumers for high-quality dry-cured fish. This study investigates the relationship between microbial diversity and the changes in physicochemical properties and non-volatile flavor compounds of dry-cured Spanish mackerel (DCSM) throughout the curing process. Our findings demonstrate that moisture content significantly decreased during curing, while NaCl generally increased. The nitrite level of 1.52mg/kg, meeting national safety standards. Additionally, there was a significant increase in hardness and chewiness. The synergistic effect of glutamic acid (Glu), alanine (Ala), and histidine (His) with inosine monophosphate (IMP), adenosine monophosphate (AMP) and guanosine monophosphate (GMP) enhanced the umami taste. Proteobacteria and Photobacteria are the main microorganisms of DCSM at the phylum and genus levels. Proteobacteria and Photobacteria are the main microorganisms of DCSM at the phylum and genus levels. Photobacterium, Moritella, and Pseudomonas were positively correlated with AMP, GMP, Ala, and Glu. And negatively correlated with nitrite and TBARS. These findings suggest that specific microorganisms positively influence the quality of DCSM through their metabolic activities. This research enhances our understanding of flavor formation mechanisms and provides critical insights for optimizing DCSM processing and quality control.

Mechanism of pyrazines and thioethers formation promoted by high oxygen concentration in the methionine‐glucose Maillard reaction system

AbstractBACKGROUNDThe typical aroma compounds in methionine‐glucose Maillard products often undergo further degradation and polymerization during storage and thermal processing, leading to flavor dispersion and aroma distortion. It is crucial to identify measures that enhance typical aroma substances in such flavor matrices.RESULTSThe effect of oxygen on the flavor formation of methionine‐glucose thermal reaction system was explored by determining typical flavor substance contents and flavor differences. Compared with the oxygen concentration in the air (21%), a high oxygen concentration (30% and 40%) effectively promoted the formation of typical flavor substances. Pyrazines increased by 44% and thioethers increased by 13%. The reaction process and the content of key substances were both measured to explain the involvement of oxygen. It was found that high oxygen concentration increased the reaction efficiency of glucose and methionine and promoted the formation of α‐dicarbonyl compounds, including glyoxal, methylglyoxal and 3‐deoxyglucosinone. Moreover, a glyoxal‐methylglyoxal‐methionine model system was established to verify the effect of oxygen intervention on the formation of pyrazines and thioethers generating from α‐dicarbonyl compounds. It was confirmed that a high oxygen concentration promoted the consumption of glyoxal and methylglyoxal, which were more readily converted into pyrazines and thioethers without forming melanoidins.CONCLUSIONA high concentration of oxygen promoted the formation of pyrazines and thioethers during the Maillard reaction of methionine and glucose, and effectively inhibited the occurrence of browning. The present study provides a new concept for the typical flavor enhancement of methionine‐glucose Maillard reaction products. © 2024 Society of Chemical Industry.

Undesirable volatile compound analysis in infant formula based on nutritional analysis, GC-MS, and recombination/omission experiments methods

Infant formula (IF), rich in essential nutrients such as polyunsaturated fatty acids crucial for infant growth, is susceptible to quality deterioration due to fatty acid oxidation. This study aimed to analyze nutritional changes and off-flavors in commercially available one-stage IFs. Specifically, the study assessed the content of protein, lipid, and lactose. Headspace solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS) was then used to analyze volatile compounds. Using Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA), the four samples can be distinctly separated. Odor activity values (OAVs) and variable importance in projection (VIP) were calculated to identify key odorant components. Subsequent recombinant/omission experiments confirmed pentanal, (E,E)-2,4-decadienal, hexanal, (E)-2-nonenal, and 1-penten-3-one as key contributors to off-flavors in IF. These findings provide a scientific basis for preventing the formation of undesirable flavors and preserving the nutritional integrity of one-stage IF during commercialization.

Dynamics of microbial communities and metabolites during the fermentation of Ningxia goji berry wine: An integrated metagenomics and metabolomics approach.

Ningxia Goji Berry Wine (NGBW), a traditional Chinese fermented beverage, exhibits complex flavor quality changes during fermentation, the mechanisms of which remain insufficiently elucidated. This study aimed to elucidate the dynamic shifts in physicochemical properties, metabolites, and microbial communities throughout the controlled fermentation process of NGBW. Metabolomic analysis identified 8 key differential volatile metabolites (VOCs) and 406 differential non-volatile metabolites. The enrichment analysis of KEGG metabolic pathways revealed that, during the fermentation of NGBW, ten critical metabolic pathways-Purine metabolism, Glycine, Serine, and Threonine metabolism, Galactose metabolism, and the Citric Acid (TCA) Cycle-play essential roles. Amplicon sequencing indicated that 25 bacterial genera dominated the microbial ecosystem (relative abundance≥0.1%). Spearman correlation analysis revealed significant associations between 5 core microorganism and flavor compounds, and 25 core microbes with non-volatile metabolites, suggesting their pivotal roles in flavor formation. This study provides a theoretical basis for optimizing the fermentation process and enhancing the flavor quality of NGBW.

Mechanism of differentiated and targeted catalysis in complex lipid system under lipase and lipoxygenase mediation.

The regulation of reaction rate differentiation, catalytic precursor differentiation, and end-product differentiation during enzyme-mediated reactions within complex lipid systems is a key area of research in flavor regulation. A multilayer lipid oxidation model, utilizing Plaice bone oil (PBO), lipase, and lipoxygenase, was employed to investigate oxidation differences between various lipids and corresponding flavor formation patterns. Lipase treatment resulted in higher levels of non‑oxygenated volatile compounds and saturated aldehydes, whereas lipoxygenase treatment increased oxygenated compounds, particularly (E)-2-hexenal, 1-penten-3-one, and 2-pentylfuran. The hydrolysis of triglycerides by lipase significantly raised the concentration of monounsaturated fatty acids. Lipoxygenase catalyzed the formation of position-specific oxidation products at the ω-6 carbon position of PUFAs, such as 15-hydroperoxy-EPA and 17-hydroperoxy-DHA. These enzymatic treatments altered the lipid profile, leading to distinct flavor formation patterns. This study provides valuable insights into the mechanisms underlying enzyme-mediated volatile substance variations in food.