Search Results (431)

Physalis pubescens L. is a seasonal fruit with high nutritional value but a short shelf life that limits its processing and utilization. This study integrated metagenomics and metabolomics to investigate the comparative effects of Lactiplantibacillus plantarum fermentation on volatile flavor metabolites and microbial community composition of P. pubescens by comparing initial (0 h) and post-fermentation (24 h) states. After 24 h of fermentation, 1316 volatile compounds were putatively identified by GC-MS, with 592 metabolites significantly changed and 501 upregulated and 91 downregulated. Key flavor compounds that impart citrus, floral, fruity, and rose notes including D-limonene, geraniol, D-carvone, and phenylethyl alcohol were markedly increased. Metagenomic analysis revealed that L. plantarum rapidly dominated the microbial community (relative abundance surged from <0.05% to ~72%) while effectively suppressing potential spoilage bacteria such as Escherichia coli. Functional gene annotation demonstrated significant enrichment of amino acid, carbohydrate, and fatty acid metabolism pathways, with key enzyme genes (L-lactate dehydrogenase, pyruvate oxidase, acetyl-CoA carboxylase) predominantly assigned to L. plantarum, suggesting their potential contribution to the generation of organic acids, ethanol, and esters. Spearman correlation analysis indicated that Lactobacillaceae genera were significantly positively correlated with terpenoids, phenols, alcohols, and aldehydes. This study provides the first metagenomics-metabolomics insight into the microbial and molecular mechanisms associated with flavor formation in LAB-fermented P. pubescens, offering a theoretical foundation for developing stable and controllable fermented fruit products. Full article

Pixian Doubanjiang (PXDB) is a traditional Chinese fermented condiment whose characteristic aroma and taste are strongly influenced by fermentation conditions. This study aimed to systematically compare the flavor profiles of PXDB produced via traditional open fermentation (TOF) and industrial closed fermentation (ICF), aiming to elucidate the chemical basis of sensory divergence and provide scientific support for industrial process optimization. In this study, PXDB samples were evaluated using sensory evaluation, GC-IMS, ¹H-NMR metabolomics, and multivariate statistical analysis. Sensory evaluation revealed that ICF exhibited a stronger soy sauce-like aroma, alcohol note, and umami intensity, whereas TOF and ICF showed comparable sweetness, sourness, chili-like aroma, and roasted aroma. GC-IMS putatively identified 126 volatile compounds, and multivariate analyses demonstrated a clear separation between the two fermentation modes. Based on combined criteria of VIP > 1, FDR-adjusted p < 0.05, and |fold change| > 2, 35 differential volatile compounds were identified. ICF was characterized by higher levels of esters, particularly ethyl esters, and selected ketones, while TOF showed enrichment of higher alcohols, terpenes, and sulfur compounds. ¹H-NMR analysis identified 54 non-volatile metabolites, of which 16 differed significantly between TOF and ICF, mainly involving amino acids, organic acids, and carbohydrates. Pathway analysis highlighted branched-chain amino acid and glutamate-related metabolism as key contributors to flavor divergence. Correlation analysis further revealed that soy sauce-like aroma and umami perception were strongly associated with amino acid-derived metabolites, esters, sulfur-containing compounds, and branched-chain aldehydes, highlighting the coordinated contribution of volatile and non-volatile compounds to flavor differentiation. Overall, fermentation mode was found to reshape PXDB flavor through coordinated modulation of volatile and non-volatile metabolism, providing experimental insight for improving industrial fermentation quality. Full article

Yeasts and lactic acid bacteria, as the predominant microorganisms in Shanxi aged vinegar, play critical roles in shaping its characteristic flavor profile and sensory properties. In this study, we investigated the cooperative fermentation interactions between three yeast strains and two lactic acid bacteria strains isolated from the Shanxi aged vinegar fermentation process. The results showed that Lactiplantibacillus plantarum CPL56 and Pediococcus acidilactici CPL23 promoted the growth of Saccharomyces cerevisiae JLY421 and Candida artemisiae JLY1608, while exerting an inhibitory effect on Saccharomyces cerevisiae JLQ39. Strains JLY421 and JLY1608 also promoted the growth of CPL56 and CPL23, while JLQ39 and CPL23 enhanced the growth of CPL56. Co-cultivation of strains JLY421 and CPL56 at a 1:1 ratio (v/v) resulted in significantly higher total acid and organic acid contents compared to all other combinations. Total organic acid content increased by 200.83% and 81.29% relative to the pure cultures of JLY421 and CPL56, respectively, with lactic acid and acetic acid concentrations reaching 0.3278 g/100 g and 0.0970 g/100 g, respectively. Additionally, the total ester content in this co-culture was also significantly higher than in other combinations, representing a 24.48% increase compared to the JLY421 monoculture. Co-cultivation of JLY421 and CPL56 markedly enhanced both the diversity and content of key volatile organic compounds, including isoamyl acetate, isoamyl alcohol, isobutyl acetate, ethanol, amyl butyrate, p-xylene, acetic acid, 3-hydroxy-2-butanone, and 2,3,5,6-tetramethylpyrazine, relative to their respective monocultures. This study provides foundational insight into yeasts and lactic acid bacteria composite starters in a solid sorghum medium, and may offer a useful reference for future efforts to improve the quality and efficiency of Shanxi aged vinegar production in more complete, multi-stage industrial processes. Full article

Hawthorn (Crataegus pinnatifida) pulp is characterized by high levels of organic acids and polyphenols, yet its strong acidity limits sensory acceptance. In this study, Streptococcus thermophilus 540, Lactobacillus brevis 647, and their mixed culture (1:1) were applied to ferment hawthorn pulp. Changes in organic acids, individual phenolics, free amino acids, volatile compounds, antioxidant capacity, and global metabolic profiles were systematically investigated using targeted analysis combined with untargeted metabolomics. Fermentation markedly reshaped the metabolic composition of hawthorn pulp, with mixed fermentation exhibiting the most pronounced metabolic reprogramming. Co-fermentation significantly enhanced phenolic derivatives and aromatic amino acid-related metabolites, while promoting a more balanced distribution of organic acids and esters, contributing to improved antioxidant potential and flavor coordination. Multivariate analyses confirmed that mixed fermentation formed a distinct metabolic pattern rather than a simple additive effect of single strains, characterized by expanded metabolic diversity and pathway complementarity. These findings provide mechanistic insight into strain-dependent and synergistic metabolic modulation during fruit fermentation and support mixed lactic acid bacteria fermentation as a promising strategy for improving the functional and sensory quality of hawthorn-based products. Full article

Stir-frying is an important process for terminating fermentation and improving the flavor of sour shrimp paste. This study investigated the flavor characteristics, volatile profiles, and post-storage microbial community of stir-fried sour shrimp paste. Sensory evaluation demonstrated that it exhibits a well-balanced flavor profile, characterized by fruity, soy sauce, spicy, and salty notes. Based on HS-SPME-GC-MS analysis, a total of 68 volatile compounds were identified, of which 26 made notable contributions to the aroma. Among them, esters were the most diverse group, with ethyl butyrate, ethyl acetate, and ethyl 2-methylbutyrate serving as the main contributors to the fruity aroma. Acids such as butanoic acid, acetic acid, and 2-methylbutanoic acid far exceeded their thresholds, linking to sour and spicy notes. Microbial community analysis revealed that low-abundance fermentative bacteria, such as Vagococcus and Levilactobacillus, remained detectable after storage, whereas Pseudomonas and Acinetobacter were identified as the most probable spoilage organisms. These findings provide a systematic understanding of the unique flavor of stir-fried sour shrimp paste and its potential microbial risks during storage, providing a basis for the application of stir-frying technology. Full article

The effects of ambient storage (A), cold storage (C), and frozen storage (F) on the quality, metabolomic characteristics, and sulfur-related aroma of red onion ‘Kewei Red 10’ (R10) and yellow onion ‘Kewei Yellow 14’ (Y14) were investigated using integrated non-targeted and volatile metabolomics. Ambient storage accelerated shrinkage, firmness loss, and sensory deterioration in both cultivars, whereas low-temperature storage effectively delayed quality decline. R10 exhibited better tolerance to frozen storage, while Y14 performed better under cold storage. Metabolomic analysis revealed that amino acids and lipid-related metabolites were closely associated with onion senescence in both cultivars. In contrast, flavonoids were enriched in preservation-associated subclasses in R10, whereas organic acids and their derivatives were more strongly associated with delayed senescence in Y14. Volatile metabolomic analysis identified sulfur compounds and heterocyclic sulfur compounds as the major contributors to onion aroma. Sulfur-related volatiles showed distinct cultivar-dependent accumulation patterns, with many sulfur compounds accumulating prominently in ambient-stored R10-A, whereas cold-stored Y14-C maintained relatively higher levels of characteristic onion-like aroma compounds. These findings demonstrate distinct metabolic adaptation strategies between red and yellow onions during storage and suggest that cultivar-specific storage conditions are required to optimize both shelf life and flavor quality. Full article

Blanching is a critical postharvest step that influences broccoli color, texture, flavor, and nutritional quality, and may affect the formation of warmed-over flavor (WOF) related volatile compounds under thermal processing. This study compares hot water blanching (HWB, 98 ± 1 °C, 30 to 150 s) and steam blanching (SB, 100 °C, 30 to 150 s) by analyzing color, texture, peroxidase activity, electronic nose, volatile compounds, sulforaphane content, and scanning electron microscopy (SEM) to determine how blanching conditions influence physicochemical attributes, cellular organization, and WOF-related volatile profiles in broccoli. Overall quality retention was superior with SB, particularly at 60 s, as evidenced by lower residual enzyme activity, improved firmness retention, better maintained cellular structure as observed microscopically, and higher sulforaphane retention relative to HWB. Multivariate analysis identified nine key volatile markers (variable importance in projection (VIP) > 1 and relative odor activity value (ROAV) > 1), including the WOF-associated aldehyde pentanal. Broccoli treated by SB for 60 s exhibited markedly lower levels of these aldehydes than samples subjected to HWB. Correlation analysis revealed a positive correlation between sulforaphane and sulfur-containing volatile compounds, including dimethyl disulfide and dimethyl trisulfide. This correlation mainly derived from the superimposed degradation of different precursor pools under thermal action: at high temperatures, dimethyl disulfide is one of the main volatile products generated from the thermal degradation of sulforaphane; meanwhile, during heating, intermediates derived from S-methyl-l-cysteine sulfoxide undergo thermal reactions to form dimethyl disulfide and dimethyl trisulfide. Collectively, these results support SB as an effective strategy to mitigate WOF while maintaining the nutritional quality of broccoli and potentially other cruciferous vegetables. Full article

Blueberry fruit quality is characterized by multi-dimensional traits such as color, sugar-acid flavor, and volatile aroma. However, variations in progeny metabolites during seedling selection need further study. This research used the blueberry variety ‘Baldwin’ (BW) and its seedling offspring (BWSO) to compare fruit appearance, as well as sugar and acid components, anthocyanin monomers, and volatile metabolites. High-performance liquid chromatography was used to analyze anthocyanins, sugars, and acids, and gas chromatography–mass spectrometry was used to analyze volatile compounds. The results showed that, compared with BW, BWSO had a blacker skin and a lower L* value. Its total anthocyanin content increased by 35.90%, with delphinidin increasing the most (52.70%); component ratios were reconstructed. The main organic acids in BWSO decreased; titratable acid dropped by 29.82%, and the total soluble solids–acid ratio rose by 37.49%, indicating a good low-acid, high-sugar flavor. Forty-three differential volatile metabolites were found, and BWSO differed from BW in its green, fruity, and floral flavors. Notably, BWSO’s vitamin C (Vc) content decreased by 70.45% compared to BW, and Vc was negatively correlated with anthocyanin components. In conclusion, BWSO exhibits a black phenotype due to elevated total anthocyanins and restructured component ratios. Its low-acid trait yields better taste, but the antagonism between anthocyanin and Vc means balanced nutritional quality selection is crucial in dark-blueberry breeding. These findings offer new insights into the mechanism of color variation and provide a reference for balanced quality trait selection in seedling selection. Full article

Fruity natural flavors are widely used in food, cosmetics, and tobacco products, and their flavor profiles directly affect the sensory quality of the final products. However, the volatile organic compound systems in these flavors are highly complex, and severe co-elution among volatile components makes effective component resolution a persistent analytical challenge. In this study, comprehensive two-dimensional gas chromatography–olfactometry–time-of-flight mass spectrometry (GC×GC-O-TOF-MS) was employed to separate and identify volatile odor compounds in three natural fruit flavor extracts: plum, jujube, and grape. A total of 113, 103, and 85 volatile odor compounds were identified from the plum, jujube, and grape extracts, respectively. By progressively adjusting the split ratio, aroma extract dilution analysis was performed, leading to the screening of 14, 11, and 32 aroma-active compounds from the three extracts, respectively. Compounds with high flavor dilution factors were subjected to quantitative analysis, and their odor activity values were calculated. Subsequently, omission and recombination experiments were conducted to confirm the key aroma-active compounds in each extract. The results showed that octanal was a key aroma compound shared by the plum and jujube extracts, while ethyl cinnamate was common to both the plum and grape extracts. Through a molecular sensory science approach and utilizing GC×GC-O-TOF-MS chromatographic separation technology, this study provides a reliable analytical platform for aroma characterization in complex samples. It also establishes a critical theoretical and data foundation for precisely identifying key aroma-active components and implementing targeted aroma modulation to enhance the natural flavor quality of fruits. Full article

Koji production is a critical process that determines the flavor and quality of the final soy sauce product. However, the complex mechanisms underlying microbial metabolism and the evolution of the physicochemical environment still require further analysis. This study focuses on three parallel koji rooms in an industrialized koji fermentation process. This work tracked the dynamics of physicochemical indices, volatile flavor compounds, and microbial communities over a full 40 h cycle. Data integration and correlation analysis elucidated the close linkage between the microbial community, the fermentation environment, and flavor formation. Koji moisture declined gradually, with faster losses at later fermentation stages. This physiological dehydration arose from microbial metabolic heat, forced aeration and structural loosening of koji, not simple physical evaporation. System pH displayed a typical U-shaped trend across fermentation. Values dropped early, most likely driven by accumulating organic acids, before rising from mid to late fermentation. This pH rebound was tentatively attributed to ammonia release from proteolytic breakdown, which may neutralize acidic compounds. These observations cast doubt on the conventional assumption that organic acid levels may be reliably estimated solely from pH measurements. Physicochemical analysis showed continuous accumulation of amino acid nitrogen (0.6–0.9 g/100 g) and total acidity throughout fermentation. By contrast, reducing sugar concentrations differed across individual koji rooms, presumably owing to divergent microbial adaptation in early fermentation. A total of 77 common compounds were identified, among which 13 key odor-active compounds with OAV ≥ 1, such as 4-vinylguaiacol and 3-methylbutyraldehyde, constitute the characteristic flavor profile of soy sauce starter culture. High-throughput sequencing uncovered a distinct ecological pattern: eukaryotic communities, dominated by Aspergillus oryzae, converged under controlled regulation. While prokaryotic communities differentiated dynamically, driven by spatial heterogeneity in the semi-open fermentation environment. Spearman correlation analysis further indicated potential functional partitioning: high-abundance taxa (e.g., Aspergillus oryzae, Weissella) were predominantly associated with macromolecular substrate degradation, whereas rare low-abundance taxa (e.g., Alternaria) displayed significant correlations with the biosynthesis of key characteristic flavor compounds. This study clarifies the synergistic regulatory mechanisms linking physicochemical conditions, microbial metabolism, and flavor precursor formation during industrial koji production. The findings establish a scientific foundation for optimizing process parameters and achieving standardized quality control in soy sauce manufacturing. Full article

Gas-assisted steam explosion (GASE) disrupts raw material structures and promotes active release, but its effects on the nutritional quality and flavor of edible fungi remain unclear. Therefore, this study assessed the influence of GASE on the nutritional quality and flavor characteristics of Pleurotus eryngii. Using the sample as the raw material, we selected the GASE process parameters through single-factor experiments combined with response surface methodology and confirmation experiments. Subsequently, changes in nutrient contents and volatile/non-volatile flavor profiles were quantitatively characterized under these processing conditions. The results indicated that the selected parameters effectively disrupted the cell wall structure of the sample, resulting in a loose and porous microstructure. Consequently, the levels of protein, polysaccharides, amino acids and vitamins were significantly altered. In terms of flavor, this process modified the relative odor activity values of key aroma compounds, including volatile aldehydes and pyrazines, while also affecting the distribution of non-volatile metabolites. This led to the enrichment of flavor compounds such as nucleotides and their derivatives, and organic acids. This study confirmed that GASE technology can effectively enhance the nutritional quality and flavor characteristics of the mushroom by regulating its microstructure and metabolite composition. Full article

Citri Reticulatae Pericarpium (CRP), a traditional functional food with various cultivars, is widely used in spices and food additives. However, systematic comparisons of flavor and chemical profiles across mainstream cultivars remain lacking. This study systematically analyzed the flavor characteristics, volatile/non-volatile metabolic profiles, and antioxidant activity of six mainstream CRP cultivars. A total of 455 volatile organic compounds (VOCs) were identified, among which terpenoids showed distinct cultivar-specific accumulation and strongly affected aroma; 35 key VOCs were screened as pivotal contributors to distinct aroma profiles. Untargeted metabolomics identified 1289 non-volatile metabolites, among which polymethoxyflavones and flavonoid glycosides exhibited significant cultivar-specific accumulation. The six CRP cultivars showed five distinct metabolic accumulation patterns, which significantly affected the differences in bioactive compound accumulation and flavor formation among different cultivars. This study reveals the aroma formation basis and metabolic features of mainstream CRP cultivars, offering insights into CRP functional food development and genetic breeding. Full article

Objectives: To evaluate the effects of replacing soybean meal (SBM) with rapeseed meal (RSM) or cottonseed meal (CSM) in finishing lamb diets on meat, untargeted metabolomics were used to explore underlying mechanisms of metabolites related to Volatile Organic Compounds (VOCs) between raw and cooked meat. Methods: Twenty-four lambs were fed isocaloric and isonitrogenous diets for 90 days and longissimus thoracic (LT) meat was sampled for quality evaluation. Results: Results showed that growth performance and most traits of meat were unaffected, including feed intake, average daily growth, pH, cooking loss, shear force, most color values, and fatty acids. However, the yellowness (b*) in RSM and CSM meat, as well as Met and Tyr in CSM meat, were increased. Muscle metabolomics identified five different metabolite-associated flavor precursors that varied, including galactose, L-pyrdosine, and 13-octadecenoic acid. In total, 223 VOCs detected in cooked meat showed no major differences among diets. Key flavor compounds, including 1-octen-3-ol and lipid-derived aldehydes, were consistent across treatments. Conclusions: In conclusion, RSM and CSM are viable SBM alternatives, changes in raw meat metabolites do not alter the volatile compounds of cooked meat. Full article

This study investigated the effects of Lactiplantibacillus plantarum SJ-4 inoculation, partial replacement of sodium chloride (NaCl) with potassium chloride (KCl) and calcium ascorbate (CaA), and their combined treatment on the fermentation quality of fermented pork sour meat. Microbial community and metabolomic analyses were further integrated to explore the potential mechanisms related to flavor formation and quality changes. The combined treatment (LP + K-Ca group) improved the flavor profile, increased the contents of volatile compounds and free amino acids, reduced several undesirable flavor-related compounds, and contributed to better fermentation quality. Compared with the control group (C), total free amino acids and essential amino acids in the LP + K-Ca group increased by 4.95% and 22.71%, respectively, while the contents of undesirable compounds such as 2-nonenal, hypoxanthine, and ketones decreased by 73.65%, 73.40%, and 9.58%, respectively. Key flavor-related microorganisms included Macrococcus, Staphylococcus, and Lactiplantibacillus. These microorganisms are intricately linked to metabolic products such as amino acids, fatty acids, and organic acids, which may provide important precursors for volatile flavor formation. Overall, the combined treatment of 40% NaCl replacement with 24% KCl and 16% CaA, together with 2% L. plantarum SJ-4 inoculation, showed potential for improving flavor formation and fermentation quality in salt-reduced sour meat based on partial NaCl replacement. Full article

The flavor profile of Longmen rice vinegar directly influences consumer purchase intention, and understanding its variation during fermentation is crucial for final product quality control. In this study, the flavor dynamics during the fermentation of Longmen rice vinegar were systematically investigated. Sensory evaluation indicated that acidity increased significantly during the acetic acid fermentation stage, while alcoholic and fermented odors decreased continuously. Instrumental analysis identified 129 volatile compounds, predominantly esters, alcohols, and acids. Based on relative odor activity value (r-OAV) analysis, acetic acid, 3-methylbutyl acetate, 2,3-butanedione, benzeneacetaldehyde, phenethyl alcohol, ethyl acetate, 2-phenylethyl acetate, ethyl 4-methyl-pentanoate, 3-methyl-1-butanol, and 3-methylbutanal were determined to be the major contributors to the overall aroma. Orthogonal partial least-squares discriminant analysis (OPLS-DA) further screened 21 key differential compounds. Significant variations in organic acid and amino acid contents during fermentation were also observed. Correlation analysis revealed relationships between key aroma compounds and organic, as well as amino, acids. These findings establish a foundation for monitoring flavor dynamics during the fermentation of Longmen rice vinegar. Full article