Main Flavor Research Articles

Development of a flavor-oriented synthetic microbial community for pour-over rice wine: A comprehensive microbial community analysis

Huangjiu, a traditional Chinese alcoholic beverage, varies widely in quality and consistency when brewed using the traditional pour-over rice wine technique, largely due to the variability in its microbial community in an open fermentation environment. This study streamlined the microbial complexity using amplicon sequencing and culture-dependent methods, leading to the identification of a set of core microbial species instrumental in flavor development. A synthetic microbial community was crafted from these key species and employed in fermentation experiments. In this study, we demonstrated that the synthetic microbial community not only replicated the major flavor profiles of traditional pour-over rice wine but also it is further proved that the core species directly determines the main flavor of pour-over rice wine, these findings are supported by our quantitative analysis of volatile compounds and sensory evaluation data. This research underscores the potential of synthetic microbial communities in standardizing production processes and improving the sensory quality of traditional beverages like Huangjiu.

Comparison of Flavor Differences between the Juices and Wines of Four Strawberry Cultivars Using Two-Dimensional Gas Chromatography-Time-of-Flight Mass Spectrometry and Sensory Evaluation

Fruit wine production is a practical approach for extending the shelf life and enhancing the value of strawberries (Fragaria × ananassa). Fruit cultivars and juices are important sources of volatile organic compounds (VOCs) that determine fruit wine sensory quality. In this study, VOCs in the juices and wines of four strawberry cultivars were identified using two-dimensional gas chromatography-time-of-flight mass spectrometry, and a sensory analysis of the wines was performed. A total of 1028 VOCs were detected. PCA and OPLS-DA distinguished the four cultivars from which the juices and wines were made. Six VOCs with variable importance in projection values greater than one were the main aroma and flavor components of strawberry wines. ZJ wine had the highest sensory scores for coordination (9.0) and overall evaluation (8.9) among the 18 descriptors of strawberry wine evaluated. Overall, the ZJ wine had the highest alcohol content (13.25 ± 0.59%, v/v) and sensory evaluation score, indicating that the ZJ cultivar is more suitable for fermentation. This study reflects the differences between wines made from four strawberry cultivars and provides a reference for brewing fruit wines.

Generation of a synthetic autochthonous microbiota responsible for the essential flavors and brewing properties of Daqu

Based on the 26 strains of medium–high-temperature Daqu, seed microbial inocula and mature microbial inoculants were prepared and inoculated into crushed wheat to prepare cleaner medium–high-temperature Daqu (XQ). The physicochemical properties, flavor, and microbial profile of XQ were studied using traditional medium–high-temperature Daqu (CQ) or industry standards as controls. The results showed that the liquefaction ability, saccharification activity, esterification activity, and moisture content of XQ were better than those of Daqu industry standards. The results of GC–MS and E-nose analyses showed that the main flavor compounds in the two types of Daqu were esters, alcohols, acids, and aldehydes, which had similar flavor profiles. Microbial sequencing revealed that the most abundant fungi in XQ were Aspergillus subflavus, Wickerhamomyces anomalus, Rhizopus oryzae, and Candida tropicalis, whereas the most abundant bacteria were Lactobacillus curvatus, Weissella cibaria, and Bacillus subtilis. Both types of Daqu contained a high abundance of W. anomalus. In addition, the COG (Clusters of Orthologous Groups of Proteins) analyses displayed that the two types of Daqu had their dominant functions and generally had the pathways and functional characteristics of organism growth and metabolism. This study laid some experimental research bases for the preparation of cleaner Daqu and could provide insights for producing safer microbial fermented foods.

Combined analysis of transcriptome and metabolome reveals the effects of novel aroma-producing Naumovozyma castellii on Feng-flavor Baijiu

Feng-flavor Baijiu has an elegant and pleasant aroma and is one of the four traditional famous liquors in China. A strain of Naumovozyma castellii XF0241 with excellent fermentation performance and rich aroma compounds was isolated and screened from the Feng-flavor fermented grains. Metabolomic analysis showed that the main flavor compounds of XF0241 are esters, terpenes, and heterocyclic compounds, which are important aroma and flavor compounds in Feng-flavor Baijiu. Compared with the model strain N. castellii CBS4309, the yeast's ester, terpenes and heterocyclic compounds were up-regulated by 168.99±45.31 %, 103.54±28.45% and 108.46±36.78% respectively. After adding additional XF0241 to the Feng-flavor fermented grains, the flavor compounds became more abundant, among which the ester showed the highest increase, followed by terpenoids and heterocyclic compounds. Transcriptomic analysis showed that 1134 genes were differentially expressed. The combined analysis of transcriptome and metabolome revealed that 10 enzymes related to ester production and 3 enzymes related to terpenoid biosynthesis, and 1 enzyme related to heterocyclic formation were significantly upregulated. We believe that XF0241 is one of the core yeasts of Feng-flavor Baijiu. Its production of rich aroma compounds plays an important role in the formation of the special aroma of liquor.

The dynamic changes and correlations between biochemical properties, flavor and microbial community during fermentation of asparagus by-products

Asparagus by-products are the promising resource that urgently need to be re-valorized. This study investigated the dynamic changes in physicochemical properties, organic acids, free amino acids, volatile flavor compounds, microbial succession, and their correlations during 7-day spontaneous fermentation of asparagus by-products. Dominant organic acids (lactic acid and acetic acid) and free amino acids (Ser, Glu, and Ala) increased with fermentation time, with lactic acid reaching 7.73 ± 0.05 mg/mL and Ser increasing 56-fold after 7 days. A total of 58 volatile flavor compounds were identified using headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPEM/GC–MS), with esters, alcohols and acids as the main volatile flavor compounds. Fourteen volatile flavor compounds had odor activity value >1. High-throughput sequencing showed Firmicutes and Proteobacteria as the main bacterial phyla, dominated by lactic acid bacteria (Levilactobacillus, Lactiplantibacillus, Weissella). Correlation analysis revealed that five bacterial genera (Levilactobacillus, Lactiplantibacillus, Enterobacter, Pediococcus and Acetobacter) were highly correlated with organic acids, free amino acids, and volatile flavor compounds, indicating their pivotal role in forming the characteristic flavor of fermented asparagus by-products (FAPS). This study provides new insights into the flavor and microbial profile of FAPS, offering a strategy for value-added processing and industrial production.

UPLC-MS/MS and HS-SPME-GC–MS reveal the flavor profiles of two geographical indications woody vegetables: Staphylea bumalda and Staphylea holocarpa

Staphylea bumalda (SHC) and Staphylea holocarpa (PGG) were recognized as geographical indication agricultural products due to unique flavor. 1218 differential non-volatile compounds and 536 differential volatile compounds were detected and identified through UPLC-MS/MS and HS-SPME-GC–MS methods. In SHC samples, catechins, epicatechins, proanthocyanidins, quinic acid derivatives, and kaempferol glycoside derivatives were the main flavor compounds, with bitter and harsh taste. L-tartaric acid, citraconic acid and citric acid were contributed to increase acidity. 4-Hexen-1-ol acetate, butanoic acid butyl ester, 3-Hexen-1-ol acetate, (E)-, and 3-Hexen-1-ol acetate, (Z)- were identified as characteristic odor compounds with strong floral, fruity and sweet odor. In PGG samples, epicatechin gallate, quercetin glycoside derivatives, L-histidine, and L-tyrosine were the leading contributors to bitter and harsh taste. The spicy, herbal, and bad smell odor were mainly brought by 2-octanol, and 3-Octen-1-ol, (Z)-. Our results offered comprehensive insights into the flavor and quality characteristics differences between PGG and SHC.

Exploring the differences in sauce‐flavour Daqu from different regions and its contribution to Baijiu brewing based on microbial communities and flavours

SummaryDaqu is an essential saccharification and fermentation agent in Baijiu brewing, and its characteristics affect the yield, quality, and flavour of Baijiu. The fundamental reason is that Daqu can provide rich microbial resources, complex enzyme systems, and raw materials for the Baijiu brewing process. In this study, three sauce‐flavour Daqu from two production areas, Beijing and Guizhou, were selected to focus on discussing and analysing the main contributions of sauce‐flavour Daqu itself to Baijiu brewing without interference from the external environment. The differences in the flavour composition and microbial communities of three Daqu were analysed. Microbial biomarkers were analysed by Lefse multilevel discriminant analysis for three Daqu. We found that different regions have their own biomarkers. Citrobacter, Rhodococcus, and Pseudomonas, were biomarkers of HD Daqu. Oceanobacillus, Aspergillus and Pichia were biomarkers of MT Daqu. Bacillus, Pediococcus and Fusarium were biomarkers of WM Daqu. A solid‐state simulation fermentation experiment was carried out to analyse changes in the flavour composition and microbial communities of fermented grains after 35 days of fermentation. The results showed that the microbial communities and the flavour composition in the Daqu and fermented samples differed significantly. The dominant microorganism genus evolved from Citrobacter, Rhodococcus, and Thermomyces to Lactobacillus, Pediococcus, and Pichia HD sample. The dominant microorganism genus in WM sample changed from Virgibacillus, Oceanobacillus, and Thermomyces to Lactobacillus, Pediococcus, and Pichia. Whereas in MT sample, the dominant microorganism genus evolved from Virgibacillus, Kroppenstedtia, and Thermomyces to Lactobacillus, Pediococcus, and Pichia. Additionally, the main flavour composition also changed after fermentation, which in the late fermentation period were phenylethyl alcohol, ethyl palmitate, tetramethylpyrazine, and 3‐methylbutanoic acid. These findings can provide support to explain the importance and contribution of sauce‐flavour Daqu in Baijiu brewing scientifically.

Analysis of the microbial community structure and characteristic flavor of traditional fermented bean paste.

Bean paste is a traditional Chinese fermented condiment, which is loved by consumers for its pleasant flavor and nutritional properties. However, the microbial communities and related flavor compounds in bean paste remain unclear. We studied the correlation between the core functional microorganisms and flavor compounds in bean paste samples at different fermentation stages. Bacterial and fungal communities changed significantly during fermentation. The results indicated that the dominant bacterial genera were Staphylococcus, Lactococcus, and Bacillus. The dominant fungi were Aspergillus and Lichtheimia. During the early and late stages of bean paste fermentation, alcohols, hydrocarbons, esters, and phenols were the main flavor compounds detected. The types and proportions of alcohols and esters in the bean pastes fermented for different durations were similar, whereas the relative contents of phenols and hydrocarbons were higher in the later stages of fermentation. Correlation analysis revealed that core functional microorganisms played a key role in the fermentation process, and the potential correlation between bacterial genera and flavors was stronger than that of fungal genera. Staphylococcus abundance was significantly correlated with the flavor levels of ethyl oleate, ç-pinene, diallyl disulfide, á-myrcene, D-limonene, and tetradecanoic acid, ethyl ester. The abundance of Aspergillus and Lichtheimia was significantly correlated with the flavor levels of á-myrcene, ç-pinene, and DL-3-phenyllactic acid. This study explored the relationship between microorganisms and flavor compounds in bean paste to deepen our understanding of the mechanism of flavor formation for bean paste.

Study on the Changes and Correlation of Microorganisms and Flavor in Different Processing Stages of Mianning Ham.

(1) Background: Mianning ham is a dry-cured ham from Southwest China, known for its distinct regional characteristics and delicious taste. It is particularly favored by consumers due to its safety, as no artificial nitrites are added during processing. The microbial changes during its different processing stages significantly influence the final product's flavor. This study aims to investigate the changes in microbial communities and flavor compounds across the nine stages of Mianning ham production, from raw material preparation to salting, drying, fermentation, and maturation, using 16S and ITS sequencing, as well as solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The goal is to explore the correlation between these changes and provide a basis for process improvement from the initial raw material preparation. (2) Results: The microbiota of Mianning ham across different processing stages mainly consisted of Proteobacteria, Firmicutes, and Ascomycota. A total of 324 volatile compounds were identified, of which 27 were key contributors to the ham's flavor. Aldehydes contributed the most to flavor, with octanal, trans-2-nonenal, and trans, trans-2,4-decadienal being the most significant contributors at various stages. Mature Mianning ham, fermented for 1-3 years, exhibited fresh grass and earthy aromas, buttery and fatty flavors, and a distinctive roasted potato note. Correlation analysis revealed that Cobetia was the primary bacterial contributor to the main flavor compounds, especially prominent in the second year of fermentation. Among fungi, Yamadazyma and Aspergillus positively influenced several key aldehyde flavor compounds throughout the processing stages, significantly contributing to the flavor profile of Mianning ham. (3) Conclusions: Correlation analysis showed that the Mianning ham that matured for two years had the richest and most characteristic flavor. The positive and consistent impact of fungi on the ham's flavor suggests that they may warrant further research and application in Mianning ham production. This provides a theoretical basis for improving the flavor quality and enhancing the market competitiveness of Mianning ham. One of the key features of Mianning ham is its substantial accumulation of hydrocarbons, which surpasses that of hams from other regions in China. A notable characteristic of Mianning ham processing is the absence of artificially added nitrites as antioxidants and color fixatives. Whether this absence is a contributing factor to the significant accumulation of hydrocarbons warrants further investigation.

Dynamic changes in volatile profiles and bacterial communities during natural fermentation of Mei yu, traditional Chinese fermented fish pieces

Microbial metabolism is important for the unique flavor formation of Mei yu, a kind of traditional Chinese fermented fish pieces. However, the interactive relationship between microorganisms and flavor components during fermentation is still unclear. In this study, electronic nose and headspace-solid-phase microextraction-gas chromatography-mass spectrometry analysis were performed to identify flavor components in Mei yu during the fermentation, and the absolute microbial quantification was conducted to identify the diversity and succession of microbial communities. During fermentation, there was an increase in the types of volatile compounds. Alcohols, aldehydes, aromatics and esters were the main flavor compounds and significantly increased in Mei yu, while hydrocarbon and aldehydes significantly decreased. The absolute abundances of Lactobacillus, Lactococcus and Weissella increased significantly after 3 days’ fermentation, which were closely associated with the productions of 1-nonanol, 2-methoxy-4-vinylphenol, guaiacol, ethyl palmitate and ethyl caprylate that might though pathways related to fatty acid biosynthesis and amino acid metabolism. However, these genera were negatively correlated with the production of indole. Additionally, the total volatile basic nitrogen (TVB-N) levels of Mei yu fermented during 3 days were within the limits of 25 mg TVB-N/100 g fish, with the contents of free amino acids and lipoxygenase activities were significant lower than that of 4 days’ fermentation. In view of food safety and flavor, it suggested that the natural fermented Mei yu at room temperature should be controlled within 3 days. This study highlights the application of absolute quantification to microbiome analysis in traditional fermented Mei yu and provides new insights into the roles of microorganisms in flavor formation during fermentation.

Investigation of the quality of rapeseed oil derived from different varieties and growth periods based on GC-IMS technique

Rapeseed oil is consumed worldwide, and its quality is closely related to the raw rapeseed material. In this work, the quality and flavor differences of rapeseed oil from twelve varieties with two growth periods were studied. The results showed that different varieties responded differently to changes in growth periods, with the GXY1 variety having the greatest combined effect. Shortening the growth period may reduce the moisture and protein content and increase the oil content of rapeseed. It may also enhance the oleic acid content and decrease the linoleic acid content. A total of 62 aroma compounds were identified by gas chromatography-ion migration spectrometry (GC-IMS), with aldehydes being the main flavor compounds. The flavor fingerprint of rapeseed oil derived from different varieties was effectively constructed. Seven key aroma compounds with relative odor activity value (ROAV) > 1 were identified, which significantly influenced the flavor of rapeseed oil. This work may provide new insights for selecting favorable rapeseed varieties for industrial production of high-quality rapeseed oil.

Flavoromics Analysis of Passion Fruit-Roasted Chicken.

Currently, research on the flavor components and their dynamic changes in roasted chicken with a special flavor is rare. In this study, a passion fruit-roasted chicken was prepared, its characteristic flavor components were profiled by flavoromics, and their evolution patterns and precursors were determined. The results showed that the characteristic flavor component with the highest contribution rate was ethyl butyrate (50.44%). In particular, some unique flavor compounds were identified compared with other roasted chicken products available. The main volatile flavor components in all stages of processing were alcohols, esters, and hydrocarbons, 15 to 30 min of roasting is an important stage for establishing the aroma system, and at the end, hydrocarbons were the main volatile compounds. During the 30-day storage period, the characteristic flavor components included ethyl butyrate, ethyl maltol, β-caryophyllene, and guaiacene. In conclusion, passion fruit-roasted chicken contained many characteristic flavor components, which were mainly formed within 15 to 30 min of roasting and were basically stable during the 30-day storage period. In a word, this work prepared a novel roasted chicken and revealed its mechanism of flavor formation at different baking stages and storage periods, which provided references for industrial production.

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.

Multiple analyses of main flavor components in reconstituted tobacco and transfer behavior of their key substances during heating.

Reconstituted tobacco (RT) is a product made by reprocessing tobacco waste, experiencing a growing demand for heat-not-burn products. The purpose of this study is to analyze the main flavor ingredients in RT aerosol, as well as the transfer behavior of key flavor substances from substrates to aerosol and the concentrations of these compounds in the substrate after heating. First, we demonstrated that the odor of four RT aerosol samples could be distinguished using an electronic nose. Through non-targeted analysis, 93 volatile compounds were detected by gas chromatography-mass spectrometry, and 286 non/semi-volatile compounds were identified by ultra-high-performance liquid electrophoresis chromatography-mass spectrometry in aerosol. Furthermore, we found that the formation of RT aerosol involves primarily evaporation and distillation, however, the total content delivered from unheated RT samples to aerosol remains relatively low due to compound volatility and cigarette filtration. Thermal reactions during heating indicated the pyrolysis of chlorogenic acid to generate catechol and resorcinol, while Maillard reactions involving glucose and proline produced 2,3-dihydro-3,5-dihydroxy-6-methyl-4h-pyran-4-one. The study highlighted that heating RTat approximately 300°C could mitigate the production of harmful substances while still providing a familiar sensory experience with combusted tobacco.

Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines.

Coffee pulp wines were produced through the mixed fermentation of Saccharomyces cerevisiae, and the flavor and sensory characteristics were comparatively evaluated. A total of 87 volatile components were identified from five coffee pulp wines, of which 68 were present in all samples, accounting for over 99% of the total concentration. The sample fermented contained significantly higher levels of volatile metabolites (56.80 mg/g). Alcohols (22 species) and esters (26 species) were the main flavor components, with the contents accounting for 56.45 ± 3.93% and 31.18 ± 4.24%, respectively, of the total. Furthermore, 14 characteristic components were identified as potential odor-active compounds, contributing to sweet and floral apple brandy flavor. Although the characteristic components are similar, the difference in the content makes the overall sensory evaluation of the samples different. The samples formed by fermentation of four strains, which obtained the highest score (86.46 ± 0.36) in sensory evaluation, were further interpreted and demonstrated through the Mantel test. The results of the component analysis were effectively distinguished by OPLS-DA and PCA, and this validation was supported by sensory evaluation. The research results provided a technical reference for the production of coffee pulp wines.

Effects of Foliar Ca and Mg Nutrients on the Respiration of ‘Feizixiao’ Litchi Pulp and Identification of Differential Expression Genes Associated with Respiration

The ‘Feizixiao’ litchi cultivar, predominantly grown in Hainan Province, faces the issue of “sugar receding” during fruit ripening. The application of mixed foliar nutrients containing calcium and magnesium (Ca+Mg) during the fruit pericarp’s full coloring stage was investigated to overcome this issue. Experimental trials unveiled significant alterations in litchi pulp physiochemical properties, including the main nutrient and flavor quality, the total respiration rates of the main respiratory pathways, and the activities of some important enzymes associated with Embden–Meyerhof–Parnas (EMP), the tricarboxylic acid cycle (TCA) and the pentose phosphate pathway (PPP). The Ca+Mg treatment showed higher sugar levels than the control (CK) during ripening. Notably, the application of Ca+Mg in litchi pulp inhibited respiration rates through the EMP, TCA, and PPP pathways, resulting in a strong effect. RNA sequencing analysis revealed the impact of Ca+Mg treatment on respiratory pathways, revealing differentially expressed genes (DEGs) such as pyruvate PK1, PK2 (pyruvate kinase), and PDC (pyruvate dehydrogenase complex), validated through qRT-PCR with a significant correlation to RNA-seq results. In general, Ca+Mg treatment during litchi fruit ripening overcame “sugar receding” by inhibiting the expression of respiration key metabolic pathway genes. These findings provide insights for enhancing cultivation management strategies.

Characterization of flavour components and identification of lipid flavour precursors in different cuts of pork by phospholipidomics

The lipids and volatile compounds in pork from different parts, including the loin, belly, shoulder and hind leg were analyzed by triple quadrupole tandem time-of-flight mass spectrometer (Q-TOF/MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS), respectively. Partial least squares regression (PLSR) and Pearson correlation analysis were utilized to establish the relationship between the lipids and volatile compounds. A total of 8 main flavour substances, 38 main phospholipids, and 32 main fatty acids were identified. The results showed that the key flavour compounds were mainly derived from unsaturated fatty acids and phospholipids containing unsaturated fatty acids, including oleic acid (C18:2n6c), α-Linolenic acid (C18:3n3), arachidonic acid (C20:4n6), PE O (18:1/20:4), PE O (18:2/20:4), and PE O (18:2/18:2), etc. Understanding the relationship between flavour compounds and lipids of pork will be helpful to control the quality of pork.

The difference analysis of physicochemical indexes and volatile flavor compounds of chili oil prepared from different varieties of chili pepper

Because of its peculiar flavor, chili oil is widely used in all kinds of food and is welcomed by people. Chili pepper is an important raw material affecting its quality, and commercial chili oil needs to meet various production needs, so it needs to be made with different chili peppers. However, the current compounding method mainly relies on the experience of professionals and lacks the basis of objective numerical analysis. In this study, the chroma and capsaicinoids of different chili oils were analyzed, and then the volatile components were determined by gas chromatography-mass spectrometry (GC–MS) and gas chromatography-ion migration spectrometer (GC-IMS) and electronic nose (E-nose). The results showed that Zidantou chili oil had the highest L*, b*, and color intensity (ΔE) (52.76 ± 0.52, 88.72 ± 0.89, and 118.84 ± 1.14), but the color was tended to be greenyellow. Xinyidai chili oil had the highest a* (65.04 ± 0.2). But its b* and L* were relatively low (76.17 ± 0.29 and 45.41 ± 0.16), and the oil was dark red. For capsaicinoids, Xiaomila chili oil had the highest content of capsaicinoids was 2.68 ± 0.07 g/kg, Tianjiao chili oil had the lowest content of capsaicinoids was 0.0044 ± 0.0044 g/kg. Besides, 96 and 54 volatile flavor substances were identified by GC–MS and GC-IMS respectively. And the main volatile flavor substances of chili oil were aldehydes, alcohols, ketones, and esters. A total of 11 key flavor compounds were screened by the relative odor activity value (ROAV). Moguijiao chili oil and Zidantou chili oil had a prominent grass aroma because of hexanal, while Shizhuhong chili oil, Denglongjiao chili oil, Erjingtiao chili oil, and Zhoujiao chili oil had a prominent floral aroma because of 2, 3-butanediol. Chili oils could be well divided into 3 groups by the partial least squares discriminant analysis (PLS-DA). According to the above results, the 10 kinds of chili oil had their own characteristics in color, capsaicinoids and flavor. Based on quantitative physicochemical indicators and flavor substances, the theoretical basis for the compounding of chili oil could be provided to meet the production demand more scientifically and accurately.

Succession of microbial community structure in fermented grains during the fermentation of strong-flavor Baijiu and its impact on the metabolism of acids, alcohols, and esters.

The study clarified the succession of microbial community structures in fermented grains (FG) and their association with flavor compounds, along with their potential metabolic functions. The community diversity, functional genera and metabolites in FG were investigated by polyphasic detecting approaches. There are 13 dominant microorganisms in FG (relative abundance > 1%). Moisture and acidity are the key indicators driving the succession of microbial communities in FG. Eight kinds of microorganisms were involved in the metabolism of acid, higher alcohols and ethanol in FG and the abundance of pyruvate dehydrogenase and lactate dehydrogenase were significantly higher than other enzymes (P < 0.05). The results showed that 23 main flavor compounds were the results of the interaction of dominant microorganisms in FG. This study provides a basis for the formation of flavor substances in strong-flavor Baijiu.

Effects of the Lactiplantibacillus plantarum YB-106 and Leuconostoc mesenteroides YB-23 strains on the quality and microbial diversity of spicy cabbage

Spicy cabbage is a popular fermented vegetable food. The study aimed to determine the physicochemical properties, volatile flavor components, sensory evaluation, and microbial diversity of spicy cabbage prepared using different methods. Three methods were used: single-bacteria fermentation with Lactiplantibacillus plantarum YB-106 and Leuconostoc mesenteroides YB-23, mixed fermentation (LMP) using both strains, and natural fermentation as the blank control (CON). The LMP group has the best quality of spicy cabbage and the highest sensory score. Esters and alkenes were the main volatile flavor components of the spicy cabbage by GC–MS. The fermentation time of LMP group was shorter, and the nitrite degradation rate was >60 %, which was significantly higher than that of other groups (p < 0.05). From the perspective of microbial diversity, the dominant bacteria genera in each group were Lactobacillus, Pantoea, Enterococcus and Pseudomonas. However, mixed fermentation decreased the abundance of pathogenic bacteria, of which the abundance of Serratia was <0.1 %. In conclusion, mixed fermentation can significantly improve the quality of spicy cabbage and shorten the fermentation time. These findings laid the theoretical foundation for the industrial production of high-quality spicy cabbage.