Formation Of Flavor Compounds Research Articles

Dynamic changes in dissolved oxygen concentration, microbial communities, and volatile compounds during industrial oak-barrel fermentation of Sauvignon Blanc wine

Oak-barrel fermentation is used in white wine production to enhance aroma and flavor complexity. However, the dynamics of microbial communities and their impact on the formation of flavor compounds during barrel fermentation remain unclear. This study investigated the changes in dissolved oxygen concentrations, microbial communities, and volatile compounds during Sauvignon Blanc wine fermentation in various oak barrels (new and two-year-old Francois Freres and new Taransaud) and stainless-steel tanks. We found that oak barrels had higher dissolved oxygen levels than steel tanks, with new barrels exhibiting higher levels than the old ones during fermentation. The dominant bacterial genera across all the vessels during the fermentation included Ralstonia, Pantoea, Gluconobacter, and Mesorhizobium, whereas the dominant fungal genera were Saccharomyces, Aspergillus, Alternaria, and Aureobasidium. The fermentation environment altered the microbial composition as the fermentation progressed in various vessels. Compared with steel tanks, difference in microbial composition between oak barrels was less significant. The new oak barrels increased the levels of esters, alcohols, and acids in the wine, while only minor differences were observed between old barrels and steel tanks. Correlation analysis showed that Ralstonia, Gluconobacter, Mesorhizobium, and Saccharomyces were positively correlated with the production of wine volatiles. Structural equation modeling indicated the interactions between dissolved oxygen, microbial communities, and wine aromas. The impact of dissolved oxygen on fungal communities during fermentation differed significantly between new and old oak barrels, indirectly influencing aroma. Conversely, in stainless-steel tanks, dissolved oxygen weakly influenced the bacterial and fungal communities, with the influence on wine aroma primarily dependent on the fungal communities. These findings provide valuable insights for optimizing the Sauvignon Blanc wine fermentation in oak barrels

Comparing effects of tangerine-peel (Citrus reticulata Blanco) age and concentration on deep-fried rabbit meat: Impact on heterocyclic aromatic amines, amino acids, and flavor compound formation

Many nutritional experts recommend rabbit meat as a high-protein source. However, the high temperatures used to prepare deep-fried rabbit meat (DFRM) typically produce numerous heterocyclic aromatic amines (HAAs), a class of substances with carcinogenic risks. In this study, we chromatographically evaluate changes in the volatile compounds, amino acids, and HAAs in DFRM while employing tangerine peel (TP) as an additive. A total of 35 volatile organic compounds are detected in the TP, which increase the concentrations of sweet and umami amino acids in the DFRM. Remarkably, the TP substantially inhibits the IQ-type HAAs, particularly MeIQ, MeIQx, 4,8-DiMeIQx, and PhIP, which are produced during deep frying. Correlation analyses reveal that the histidine, aldehydes, and alcohols are strongly and positively correlated (P < 0.001) with the MeIQ, MeIQx, 4,8-DiMeIQx, and PhIP production. This study offers innovative and natural approaches for reducing HAA formation during the frying of rabbit meat.

Effects of different thermal processing methods on amino acid, fatty acid, and volatile flavor substance contents of Aohan millet (Golden seedling millet)

AbstractAohan millet has been cultivated for 8000 years and has rich nutritional value, such as high‐quality fatty acids and amino acids. Thermal processing is a conventional approach to food preparation. However, the effect of thermal processing on the formation of flavor substances in millet has not been clarified. Therefore, in this study, the effects of three different thermal processing techniques, namely, steaming, stir‐frying, and puffing, on the amino acids, fatty acids, and volatile flavor substances of Aohan millet were investigated using high‐speed automatic amino acid analyzer, headspace solid‐phase microextraction method, combined with gas chromatography–mass spectrometry (HS‐SPME/GC–MS) and gas chromatography (GC) with Aohan millet from Inner Mongolia as the raw material. All three thermal processing methods notably reduced the levels of protein, starch, polyphenols, and flavonoids in Aohan millet when compared to the raw millet (p &lt; .05). Amino acid and fatty acid contents demonstrated an increase in fried and puffed millet relative to steamed millet, with notable distinctions in amino acid and fatty acid contents between these two groups. Following the steaming process, there was a significant increase in the flavor compounds of Aohan millet, rising from 53 to 80, while this increase was not observed in the other two groups. The correlation analysis suggested that the formation of flavor compounds was predominantly influenced by the types and levels of amino acids. The study suggested that different heat treatments affected the amino acid, fatty acid, and more significantly flavor material content and composition of Aohan millet. In conclusion, steaming treatment could retain more nutrients and richer flavor substances; while puffing treatment would enhance amino acid and fatty acid content, which provides a fundamental basis for scientifically guided processing and rational culinary application of Aohan millet.

Metabolomics ravels flavor compound formation and metabolite transformation in rapid fermentation of salt-free fish sauce from catfish frames induced by mixed microbial cultures

This study demonstrates that the co-inoculation with Lactiplantibacillus plantarum, Pichia fermentans and Staphylococcus saprophyticus accelerates catfish frame fish sauce fermentation. Over a 3-day period, significant changes occurred in physicochemical properties, microbial profiles, flavor compounds, and metabolomic spectra. Notable increases in acidity coupled with decreases in glucose underscored the robust environmental adaptability of the employed microorganisms. A reduction in total amino acids, alongside a rise in umami amino acids, suggested flavor enhancement. GC–MS analysis identified 40 key volatile compounds, with esters and aldehydes crucial for aroma development. UPLC-QTOF-MS-based untargeted analysis identified 934 metabolites, with 377 differential metabolites being vital (VIP > 1.5, P < 0.05), including amino acids, peptides, organic acids, nucleic acids, and fatty acids. Metabolites linked to amino acid metabolism, particularly phenylalanine and arginine, were associated with fermentation duration. These findings offer a theoretical basis for optimizing flavor and quality in fish sauces from fish by-products through accelerated fermentation.

Foliar Co-Applications of Nitrogen and Iron on Vines at Different Developmental Stages Impacts Wine Grape (Vitis vinifera L.) Composition.

The co-application of N and Fe can improve wine grape composition and promote the formation of flavor compounds. To understand the effects of foliar co-application of N and Fe on wine grape quality and flavonoid content, urea and EDTA-FE were sprayed at three different developmental stages. Urea and EDTA-Fe were sprayed during the early stage of the expansion period, at the end of the early stage of the expansion period to the late stage of the veraison period, and during the late stage of the veraison period. The results demonstrated that the co-application of urea and EDTA-Fe, particularly N application during the late stage of the veraison period and Fe application during the early stage of the berry expansion period (N3Fe1), significantly improved grape quality. Specifically, the soluble solid content of berries increased by 2.78-19.13%, titratable acidity decreased by 6.67-18.84%, the sugar-acid ratio became more balanced, and yield increased by 13.08-40.71%. Further, there was a significant increase in the relative content of amino acids and flavonoids. In conclusion, the application of Fe and N fertilizers at the pre-expansion and late veraison stages of grapes can significantly improve the quality and yield of berries; ultimately, this establishes a foundation for future improvement in the nutritional value of grapes and wine.

Transcriptome Reveals the Key Genes Related to the Metabolism of Volatile Sulfur-Containing Compounds in Lentinula edodes Mycelium.

Lentinula edodes (L. edodes) is a globally popular edible mushroom because of its characteristic sulfur-containing flavor compounds. However, the formation of the volatile sulfur-containing compounds in the mycelium of L. edodes has not been studied. We found that there were also sulfur-containing aroma compounds in the mycelium of L. edodes, and the content and composition varied at different stages of mycelial growth and development. The γ-glutamyl-transpeptidase (GGT) and cysteine sulfoxide lyase (C-S lyase) related to the generation of sulfur compounds showed the highest activities in the 15-day sample. Candidate genes for the metabolism of volatile sulfur compounds in mycelium were screened using transcriptome analysis, including encoding the GGT enzyme, C-S lyase, fatty acid oxidase, HSP20, and P450 genes. The expression patterns of Leggt3 and Leccsl3 genes were consistent with the measured activities of GGT and C-S lyase during the cultivation of mycelium and molecular dynamics simulations showed that they could stably bind to the substrate. Our findings provide insights into the formation of sulfur-containing flavor compounds in L. edodes. The mycelium of L. edodes is suggested for use as material for the production of sulfur-containing flavor compounds.

Effect of different processing steps in the production of beer fish on volatile flavor profile and their precursors determined by HS-GC-IMS, HPLC, E-nose, and E-tongue

Beer fish is characterized by its distinctive spicy flavor and strong beer aroma. Currently, there is a lack of comprehensive research analyzing the changes in taste and volatile compounds that occur during the processing of beer fish. Thus, this study used HS-GC-IMS, electronic tongue, and electronic nose to investigate the changes in flavor components during various processing stages of beer fish. The obtained results were subsequently analyzed using multivariate statistical analysis. The results showed that the final beer fish product (SF) had the greatest amount of free amino acids (888.28 mg/100 g), with alanine, glutamic acid, and glycine contributing to the taste of SF. The inosine monophosphate (IMP) content of beer fish meat varied noticeably depending on processing stages, with deep-fried fish (FF) having the greatest IMP content (61.93 mg/100 g), followed by the final product (SF) and ultrasonic-cured fish (UF). A total of 67 volatiles were detected by GC-IMS, mainly consisting of aldehydes, ketones, and alcohols, of which aldehydes accounted for >37%, which had a great influence on the volatile flavor of beer fish. The flavor components' composition varied noticeably depending on the stage of processing. PLS-DA model screened 35 volatile flavor components (VIP > 1) as markers; the most significant differences were 1-propanethiol, isoamyl alcohol, ethanol, and eucalyptol. Ultrasonic processing, frying, and soaking sauce can significantly improve the formation of flavor compounds, resulting in a notable enhancement of the final beer fish's umami taste and overall flavor quality.

Effects of Salinity on Physicochemical Properties, Flavor Compounds, and Bacterial Communities in Broad Bean Paste-Meju Fermentation.

Broad bean paste (BBP) is a traditional fermented soy food, and its high salt content not only prolongs the fermentation time but also threatens human health. In this study, three BBP-meju with different salt concentrations were prepared, and the effects of varying salinity on fermentation were comprehensively compared. The results showed that salt-reduced fermentation contributed to the accumulation of amino acid nitrogen, reducing sugars, free amino acids, and organic acids. Alcohols, esters, aldehydes, and acids were the main volatile flavor compounds in BBP-meju, and the highest total volatile flavor compounds were found in medium-salt meju. Bacillus, Staphylococcus, Aspergillus, and Mortierella were the dominant microbial communities during fermentation, and there were also three opportunistic pathogens, Enterobacter, Pantoea, and Brevundimonas, respectively. According to Spearman correlation analysis, Wickerhamomyces, Bacillus, Staphylococcus, and Mortierella all showed highly significant positive correlations with ≥3 key flavor compounds, which may be the core functional flora. Furthermore, the dominant microbial genera worked synergistically to promote the formation of high-quality flavor compounds and inhibit the production of off-flavors during salt-reduced fermentation. This study provides a theoretical reference for the quality and safety control of low-salt fermented soy foods.

Integrated metabolomics and microbiome analysis reveal blended oil diet improves meat quality of broiler chickens by modulating flavor and gut microbiota

This study was to evaluate the effects of different dietary oils in chicken diets on meat quality, lipid metabolites, the composition of volatile compounds, and gut microbiota. Nine hundred female 817 crossbred broilers at one day old with an average body weight of 43.56 ± 0.03 g were randomly divided into five treatments, each consisting of 6 replicates of 30 birds. The control group received soybean oil (SO); other groups received diets supplemented with rice bran oil (RO), lard (LO), poultry fat (PO), and blended oil (BO), respectively. All diets were formulated as isoenergic and isonitrogenous. Compared with SO, RO decreased ADG and 42 d BW (P < 0.05). Compared with the RO, BO increased ADG and 42 d BW and decreased FCR (P < 0.05). Compared with SO, BO increased 24 h a* value and reduced the malondialdehyde (P < 0.05), and further improved drip loss of breast muscle. The proportions of C18:0 and saturated fatty acid were the highest in LO, and the proportions of C16:1, C18:1, and monounsaturated fatty acids were the highest in BO. The content of C18:2, C18:3, and polyunsaturated fatty acids were the highest in SO. The contents of glyceryl triglycerides and total esters in BO were significantly higher than those in the SO and LO group (P < 0.05). There was a substantial increment in the relative abundance of PPARα, ACOX1 and CPT1A transcripts in breast of chickens fed BO (P < 0.05). Further, dietary BO increased the relative cecal abundance of Firmicutes phylum, Ruminococcus_torques and Christensenellaceae_R-7 genera, and decreased that of Campylobacterota, Proteobacteria, and Phascolarctobacterium (P < 0.05). Genera g_Lactobacillus and Christensenellaceae_R-7 may mainly be involved in the formation of volatile flavor compounds in breast muscle. In conclusion, dietary BO improved the flavor of chickens by increasing the concentration of triglycerides and volatile flavor compounds, improving gut microbiota structure, and suppressing lipid oxidation. The potential positive effects of BO may be associated with the regulation of lipid metabolism.

Solid-state fermentation of corn to make Chinese liquor: Effect of corn variety and dynamic microbial community variation

This study aims to evaluate the impact of different corn varieties (Lancaster Sure Crop-LSC, Hickory King White-HKW, and Yellow Dent Corn-YDC) on baijiu fermentation especially focusing on ethanol yield and flavor compounds) and characteristics of dried distillers grains (DDG); and reveal the relationship between flavor compounds and the microbial community in baijiu fermentation. The results showed that LSC generated the highest ethanol (14.73%, v/v) and least methanol (6.6 g/L) concentrations in zaopei (fermented grains before distillation) among the three studied varieties. The DDG from the LSC variety had higher protein (21.14%) and fat (12.20%) contents (dry weight basis) compared to the other two varieties. The results of High-throughput sequencing indicated that both Bacillus and Weissella were dominant bacteria, while Saccharomyces, Saccharmycopsis, and Rhizopus were predominant fungi in all zaopei. In addition, 17 different flavor compounds were found in zaopei, including esters, alcohols, acids, and phenolics. Based on the Pearson correlation analysis, Bacillus, Pediococcus, Leuconostoc, Enterococcus, Weissella, and Pseudomonas, along with Saccharomyces, Saccharmycopsis, Rhizopus, and Mucor fungi, played significant roles in the formation of flavor compounds. These findings deepen our understanding of the microbial contribution to flavor compounds and will help improve baijiu quality.

Understanding the correlation between formation of flavor compounds and dominant bacteria during Luoyang mung bean sour fermentation

To understand the change of the overall flavor component, including volatile compounds and free amino acid, Luoyang mung bean sour (LMBS) was investigated by gas chromatography-mass spectrometry (GC-MS) and automatic amino acid analyzer. The results showed that the beany flavor compounds, including hexanal, 2-hexenal, hexanol, and 1-octene-3-ol, significantly decreased or even disappeared. The concentration of esters and acids, represented by caproic acid and hexyl acetate, increased during LMBS fermentation. By detecting the free amino acids, it was found that the umami taste of glutamic acid (Glu) and aspartic acid (Asp) were the dominant amino acids. Among the 7 metabolites tested, lactic acid exhibited the highest concentration and continued to accumulate during fermentation. Leuconostoc, Enterobacter, Lactobacillus, Citrobacter Pediococcus, and Lactococcus were identified as the dominant bacterial groups that exhibited fluctuations during LMBS fermentation. Ultimately, Lactobacillus emerged as the dominant species. The network of Spearman correlation analysis was employed to uncover the relationship between bacterial community and flavor compounds during the fermentation of LMBS. For the dominant bacteria, Leuconostoc, Pediococcus, and Lactobacillus were positively correlated with acetic acid, lactic acid, citric acid, alcohol, sweet and umami amino acids, while negatively correlated with ketones alcohols and bitter amino acids.

Comparative profiling of microbial communities and volatile organic compounds in fermented wrapper, binder, and filler cigar tobaccos

BackgroundEconomic benefits for tobacco growers are closely linked to the quality of fermented cigar tobacco leaves (CTLs). This research focused on an in-depth examination of the microbial community and flavor compounds within CTLs, specifically analyzing the wrapper, binder, and filler components of a cigar. The primary objective was to unravel the complex relationship between the microbial composition and the resultant flavor profiles, thereby providing insights that could enhance the economic value of CTLs.ResultsThe study revealed distinct variations in flavor chemicals and microbiota across different sections of CTLs. Prominent species identified in the fermented CTLs included Corynebacterium, Pseudomonas, Staphylococcus, Aspergillus, and Cladosporium. Bidirectional orthogonal partial least squares (O2PLS) analysis pinpointed five bacterial and four fungal species as key contributors to flavor compound formation. Additionally, an analysis considering Within-module and Among-module connectivity highlighted two bacterial and thirteen fungal genera as keystone species. The insights from Partial Least Squares Structural Equation Modeling (PLS-SEM) further underscored the influential role of fungal microorganisms in defining CTLs' flavor profile.ConclusionsThe research findings illuminate the intricate interplay between flavor chemicals and microbes in the traditional fermentation process of CTLs.Graphical

Dynamic changes and correlation of organic acids, physicochemical properties, and microbial communities during fermentation of Sichuan bran vinegar

Organic acids are essential constituents of bran vinegar, significantly influencing its sensory quality and functional characteristics. However, until now, little has been known about organic acid synthesis in bran vinegar. This study investigated the main physicochemical properties, organic acid composition, and changes in microbial diversity throughout the fermentation of Sichuan bran vinegar. Additionally, the functional microorganisms related to organic acid synthesis were analyzed. The results showed the presence of eight organic acids in bran vinegar. Amino acid nitrogen, reducing sugars, and alcohol content were identified as the main physicochemical factors contributing to organic acid formation. The dominant microorganisms associated with organic acids during fermentation included Lactobacillus, Acetobacter, Bacillus, Alternaria, Pichia, and Candida. Microbial communities related to specific organic acids during the fermentation of vinegar grains were identified using the two-way orthogonal partial least squares (O2PLS) model. Bacterial communities showed stronger correlations with the principal organic acids. These findings provided the basis for analyzing the formation of flavor compounds in the bran vinegar fermentation process.

Quantitative Proteomics Reveals the Relationship between Protein Changes and Volatile Flavor Formation in Hunan Bacon during Low-Temperature Smoking.

This study aimed to investigate the changes in proteins and volatile flavor compounds that occur in bacon during low-temperature smoking (LTS) and identify potential correlations between these changes. To achieve this, a combination of gas chromatography-mass spectrometry and proteomics was employed. A total of 42 volatile flavor compounds were identified in the bacon samples, and, during LTS, 11 key volatile flavor compounds with variable importance were found at a projection value of >1, including 2',4'-dihydroxyacetophenone, 4-methyl-2H-furan-5-one, Nonanal, etc. In total, 2017 proteins were quantified at different stages of LTS; correlation coefficients and KEGG analyses identified 27 down-regulated flavor-related proteins. Of these, seven were involved in the tricarboxylic acid (TCA) cycle, metabolic pathways, or amino acid metabolism, and they may be associated with the process of flavor formation. Furthermore, correlation coefficient analysis indicated that certain chemical parameters, such as the contents of free amino acids, carbonyl compounds, and TCA cycle components, were closely and positively correlated with the formation of key volatile flavor compounds. Combined with bioinformatic analysis, the results of this study provide insights into the proteins present in bacon at various stages of LTS. This study demonstrates the changes in proteins and the formation of volatile flavor compounds in bacon during LTS, along with their potential correlations, providing a theoretical basis for the development of green processing methods for Hunan bacon.

Effect of Different Salt Additions on the Flavor Profile of Fermented Ciba Pepper

Salt is a key ingredient that can both enhance the taste and extend the shelf life of fermented vegetables. However, it is important to note that excessive salt levels can have adverse effects on consumer health. This study aimed to investigate the impact of various salt additions (2%, 4%, 6%, 8%, and 10% wt/wt) on the flavor profile of fermented ciba pepper, a traditional Chinese fermented chili sauce, using gas chromatography–ion mobility spectrometry (GC-IMS) in combination with an electronic nose (E-nose). Fermented ciba pepper samples were prepared with different salt additions: 2% (LJA), 4% (LJB), 6% (LJC), 8% (LJD), and 10% (LJE) (wt/wt). The physicochemical and sensory properties of the fermented ciba pepper samples were evaluated. Sensory evaluation indicated that LJC and LJD received higher scores compared to the other groups. The total acid and amino acid nitrogen contents displayed contrasting trends with the salt additions (p &lt; 0.05). The E-nose analysis successfully differentiated the flavor profiles of the ciba pepper samples fermented with varying salt additions. Additionally, the GC-IMS analysis identified a total of 72 volatile compounds, including 14 alcohols, 21 esters, nine aldehydes, four acids, eight ketones, three terpenes, and eight other substances. Notably, the ciba pepper samples with lower salt additions exhibited higher levels of alcohols, aldehydes, and esters. In conclusion, the addition of salt during the fermentation process significantly influenced the formation of flavor compounds in ciba pepper. This study provides valuable insights into ciba pepper fermentation with different salt additions and offers prospects for the development of low-salt fermented ciba pepper products.

Effects of Stewing Modes on Physicochemical Quality and Formation of Flavour Compounds of Chinese Dagu Chicken Soup

Effects of Stewing Modes on Physicochemical Quality and Formation of Flavour Compounds of Chinese Dagu Chicken Soup

Effect of lipase and lipoxygenase on lipid metabolism and the formation of main volatile flavour compounds in fermented fish products: a review

SummaryLipid metabolism due to lipid hydrolysis and oxidation considerably contributes to the final product quality of fermented fish products and especially impacts its flavour. Lipase and lipoxygenase (LOX) are key enzymes involved in lipid metabolism. Endogenous lipases (lipase from fish muscle and adipose tissue) and/or exogenous lipases (lipase from microorganisms, the added lipase) catalyse the hydrolysis of lipids, producing numerous free fatty acids. LOX in fish gills and skin tissues plays an important role in lipid oxidation. During the catalysis by LOX, polyunsaturated fatty acids having cis, cis‐1,4‐pentadiene structure are oxidised, finally leading to the generation of flavour precursors or compounds such as alcohols, aldehydes, ketones, esters and acids. The addition of lipase effectively enhances the content of acidic components. Simultaneously, fermented fish products with a start culture capable of producing both lipase and LOX exhibit higher levels of flavour and aroma. In this process, the collaborative action of lipase and LOX generates a rich array of volatile flavour components. This review offers a comprehensive overview of the distinct functions and effects of both endogenous and exogenous lipase, along with LOX, in fermented fish products, as well as their roles in lipid metabolism. The study also explores their effects on the main volatile flavour compounds of fermented fish products. Moreover, the article discusses the prospects of applying lipase and LOX in fermented fish products, highlighting some limitations in current research and offering recommendations for future studies.

Effect of indigenous Saccharomyces cerevisiae strains on microbial community successions and volatile compounds changes during Longyan wine fermentation

In Longyan grape, as a unique white wine variety in China, the connection between starters and wine flavor is poorly understood. Thus, this study compared the effects of commercial yeast VL2 and three selected native Saccharomyces cerevisiae strains on the microbial community and volatile compounds during alcohol fermentation of Longyan wine. Results showed that the indigenous yeast strain FMS can initiate fermentation faster than other strains. A total of 60 aromatic compounds were identified in all fermentation samples, and the concentration of volatile compounds in wines inoculated with FMS (9619.61 ± 500.18 μg/L) was significantly higher than in VL2 wines (8358.91 ± 131.48 μg/L). Moreover, the microbial diversity differed among the four strains, with the FMS fermentation samples having the highest microbial genus of 470. The core microorganisms of VL2 (13), JCT (15), FMS (18), and FML (12) wines were identified using OPLS analysis and Spearman's correlation analysis, respectively. Among them, Lactobacillus, Paenibacillus, and Pichia were the unique microorganisms in FMS wines, which performed a crucial part in the synthesis of aromatic compounds such as hexyl acetate, ethyl butanoate, ethyl octanoate, and ethyl 9-decenoate. Therefore, FMS wines has effectively improved the quality of the wines and diversified the organoleptic quality of Longyan wines from Huaizhuo Basin. This study provided useful references for understanding the role of brewing yeast in the formation of flavor compounds during the fermentation process of Longyan dry white wine, as well as the application of indigenous brewing yeast in the wine industry.

Integrated metatranscriptomics and metabolomics reveal microbial succession and flavor formation mechanisms during the spontaneous fermentation of Laotan Suancai

Laotan Suancai, a Chinese traditional fermented vegetable, possesses a unique flavor that depends on the fermentative microbiota. However, the drivers of microbial succession and the correlation between flavor and active microbiota remain unclear. A total of 21 characteristic flavor metabolites were identified in Laotan Suancai by metabolomics, including 8 sulfides, 6 terpenes, 3 organic acids, 2 isothiocyanates, 1 ester, and 1 pyrazine. Metatranscriptome analysis revealed variations in the active microbiota at different stages of fermentation, and further analysis indicated that organic acids were the primary drivers of microbial succession. Additionally, we reconstructed the metabolic network responsible for the formation of characteristic flavor compounds and identified Companilactobacillus alimentarius, Weissella cibaria, Lactiplantibacillus plantarum, and Loigolactobacillus coryniformis as the core functional microbes involved in flavor development. This study contributed to profoundly understanding the relationship between the active microbiota and flavor quality formation, as well as the targeted selection of starters with flavor regulation abilities.

Lipidomics and GC-MS analyses of key lipids for volatile compound formation in crayfish meat under different thermal processing treatments

The changes of lipids and volatile compounds in crayfish meat under different thermal processing treatments including boiling (BO), air frying (AF), and BO-AF were analyzed by UPLC-Q-TOF-MS/MS and gas chromatography-mass spectrometry (GC-MS). The results found that a total of 596 lipids were identified from the crayfish meat. Among them, lysophosphatidylcholine (LPC) 18:1 and lysophosphatidylethanolamine (LPE) 18:1 may be the major aroma retainer for air-fried crayfish meat, while triacylglycerol (TG) 16:0_18:1_18:2 for boiled crayfish meat. Statistical analysis showed that a total of 78 lipid molecules contributed significantly to crayfish meat, of which LPE20:5, LPE22:6, LPE18:3, LPE18:0, LPE18:1, and LPE18:2 may be potential markers that distinguish air-fried crayfish meat from other thermally processed one. In addition, 14 volatile compounds were identified as characteristic aroma compounds of crayfish meat, with aldehydes and heterocyclic compounds contributing significantly to air-fried crayfish meat. LPE and diacylglycerol (DG) as key substrates for flavor compound formation during thermal processing of crayfish meat.