Flavor Development Research Articles

Characterization of the aroma and flavor profiles of guava fruit (Psidium guajava) during developing by HS-SPME-GC/MS and RNA sequencing

The flavor of guava, an important tropical fruit, is influenced by secondary metabolites. However, the mechanisms and processes underlying flavor formation in guava remain unclear. In this study, dynamic changes in volatile organic compounds (VOCs), sugars, and organic acids in guava peel and flesh across different developmental stages were investigated using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS) and high-performance liquid chromatography (HPLC). Here, we identified 90 VOCs, three sugars and eight organic acids. The dynamics of VOCs differ between the flesh and peel. The early developmental stages are more critical in influencing the variation of VOCs in the flesh, while VOC changes in peel occur more progressively across the developmental stages. By integrating transcriptomic and metabolomic analyses, we identified several key genes involved in VOC, sugar, and acid metabolism. This is the first study to describe the expression patterns of these genes throughout guava development, providing new insights into guava flavor development.

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.

Modulating fine flavor cocoa attributes: Impact of seed-to-bean transformation under controlled conditions on metabolite, volatile and sensory profiles

Fine-flavored chocolates are distinguished by their complex and distinct flavor profiles, which includes notes such as floral, fruity, nutty, and spicy. This study sought to modulate the flavor development of chocolates by establishing controlled processing conditions during the transformation from seed to bean in a laboratory setting, to produce superior quality chocolates. Our experimental setup comprised two varying temperature levels (30 °C and 45 °C) and three organic acids (OAs: acetic, lactic, and citric acids) at concentrations of 1–30 g/L to adjust the pH of the transformation system. Our study focused on how these conditions affect the development of distinct flavor profiles in chocolate bars, emphasizing the enhancement of fine-flavor notes. Flavor development was monitored through the untargeted metabolomics of cocoa beans and analyzing the volatile compounds and sensory profiles of the resultant chocolates. This study revealed that OA concentration markedly influenced metabolite formation, particularly affecting peptides, volatile organic compounds, and flavor notes. Chocolates derived from seeds processed with 30 g/L acid solutions demonstrated enhanced fruitiness and acidity, whereas those processed with 1 g/L acid solutions exhibited pronounced nuttiness and cocoa taste attributes but lower acidity. These findings underscore the significance of meticulously managing flavor development processes to produce fine-flavored chocolates with unique aromatic profiles. Crucially, variables in the controlling process, such as temperature and pH, are essential for fine-tuning flavor attributes, enabling the correlation and identification of key quality biomarkers to elucidate flavor development pathways.

Characteristics of volatile flavor development in aged longissimus lumborum post-ultrasound treatment: 4D proteomics combined with phosphoproteomics analysis

The present study aimed to evaluate the impact of ultrasonic treatment on the development of volatile flavor compounds in beef during postmortem aging and its potential mechanism. Results showed that ultrasound treatment may cause an increase in the total content of unsaturated fatty acids, which could lead to lipid oxidation and potentially result in changes in the flavor development. Additionally, it was also found that ultrasound exacerbated protein oxidation. A total of 141 volatile compounds were obtained by SPME–GC–MS analysis, and 18 differential aroma substances (P < 0.05, VIP > 1) were obtained by orthogonal partial least squares discrimination analysis (OPLS-DA). Five key volatile flavor compounds (hexanal, nonanal, octanal, pentanal, and 1-pentanol) originating from lipid oxidation were identified according to odor activity values (OAVs). The concentration of these compounds was significantly higher in the ultrasonic treatment group compared to the non-ultrasonic group that underwent a 3-day aging process. Nine common differentially expressed proteins (DEPs) were identified through the utilization of proteomics and phosphoproteomics analysis. KEGG pathways showed that selenocompound metabolism, tryptophan metabolism and cysteine and methionine metabolism led to flavor formation during wet aging of beef after ultrasound treatment. This study provided proteomic insights into the flavor of beef aged through sonication and suggested potential links between flavor development and biological processes.

The potential correlations between cell-free extracts from Rhodobacter sphaeroides grown under low-oxygen conditions and volatile organic compounds in Chinese-style sausage

Limited research has explored the use of Rhodobacter sphaeroides cell-free extracts (RCFE) in meat processing. To examine the potential application of RCFE in improving the flavor quality of Chinese-style sausage, in this study, we investigated the effects and mechanisms of RCFE grown under low-oxygen conditions on the flavor development of Chinese-style sausage, using GC–MS and 4D label-free proteomics. The GC–MS analysis detected 60 volatile organic compounds, with significant increases in acids, esters, and alcohols following the addition of RCFE (p < 0.01). Fifteen differential flavor compounds were identified as potential biomarkers to distinguish sausages. From a total of 2689 proteins, 364 differentially expressed proteins were identified (p < 0.05, |Log2FC| > 1, and VIP > 1,) in RCFE grown under low- and high-oxygen conditions. KEGG pathway analysis suggested that the RCFE grown under low-oxygen conditions may enhance alcohol and acid levels by upregulating the expression of related enzymes, which subsequently increases ester levels in the sausage.

Effects of Postharvest SO2 Treatment on Longan Aril Flavor and Glucosinolate Metabolites.

SO2 fumigation treatment (commonly known as sulfur treatment, ST) is a key method in the postharvest preservation of imported and exported fresh longan fruits, effectively reducing pericarp browning and enhancing color. Nonetheless, distinctive aromas, often referred to as "sulfur flavor", may develop in the aril during the extended preservation period. This study employed "Caopu" longan as the test material and patented SO2-releasing paper (ZL201610227848.7) as a treatment to perform a 35-day low-temperature (5 °C) storage of the fruit. The changes in glucosinolates (GSLs) and associated metabolites in the aril of treated fruit (ST) were examined utilizing ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection and widely targeted metabolomics technology. The findings indicated that following 35 days of storage, nearly all control (CK) fruit pericarp turned to brown, resulting in an edible fruit rate of 75.41% and a commercial fruit rate of 0%. In contrast, the treated (ST) fruit demonstrated an edible fruit rate and a commercial rate of 99.44%, while the pericarp color changed from dark yellow-brown to light earthy yellow. The sulfur-containing metabolites identified in longan fruit aril predominantly consist of amino acids and their derivatives (60.44%), followed by alkaloids (15.38%), nucleotides and their derivatives (1.10%), and other types (23.08%), which include GSLs. SO2 treatment significantly reduced the content of oxidized glutathione in fruit aril but increased the content of GSLs and related amino acids and their derivatives. Via screening, 19 differential sulfur-containing metabolites were obtained between ST and CK, including 11 GSLs. The identified differential metabolites of GSLs were all increased, primarily comprising aliphatic GSLs, such as 1-hydroxymethyl glucosinolate, 2-Propenyl glucosinolate (Sinigrin), and 4-Methylsulfinylbutyl glucosinolate (Glucoraphanin). Pathway analysis showed that these differential metabolites were mainly involved in coenzyme factor synthesis, cysteine and methionine metabolism, and amino acid synthesis, among other pathways. To the best of our knowledge, this is the first study to reveal the causes of the special flavor of longan aril after SO2 treatment, which is a great concern for longan consumers. Moreover, this study provides a scientific basis for exploring the reasons and mechanisms for the development of the sulfur flavor in the SO2-treated fruits during postharvest storage.

The role of physical chemistry in food and beverage

Physical chemistry is a fundamental science that underpins many critical processes in food and beverage production. This paper explores the influence of physico-chemical properties on basic reactions such as crystallization, enzyme kinetics in fermentation, and the Maillard reaction, all of which play a significant role in determining the flavor, texture, stability, and quality of food products. By examining the effects of factors like temperature, pH, solute concentration, and the presence of additives, we demonstrate physical chemistry principles guide the manipulation of these processes to optimize product characteristics. Understanding these interactions allows for greater control over food production techniques, leading to innovations in texture enhancement, flavor development, and preservation. This study highlights the importance of physical chemistry in advancing the food and beverage industry by providing insights into the molecular mechanisms that influence the sensory and functional properties of products.

Screening appropriate lactic acid bacteria as adjunct starter to enhance characteristic flavor and sensory profiles of Huangjiu (Chinese rice wine)

Lactic acid bacteria (LAB) are crucial for enhancing Huangjiu flavor, yet no standardized criteria exist for selecting LAB strains for this purpose. This study aimed to investigate the suitability of screening appropriate LAB strains as adjunct starters for Huangjiu fermentation. Twenty-five LAB strains were assessed for their stress resistance and fermentation characteristics. Co-fermentation with Saccharomyces cerevisiae was conducted to explore its role in flavor development, as this yeast greatly contribute to desirable flavor profiles. Notably, Lactiplantibacillus plantarum AR1018, AR1026 and Weissella confusa AR1038 significantly reduced 3-methyl-1-butanol production while increasing levels of ethyl hexanoate and ethyl octanoate. These strains were selected for further analysis of their impact on the physicochemical properties, volatile organic compounds, and sensory attributes of Huangjiu. The LAB starters enhanced total acidity, sugar and protein utilization and ester synthesis, while reducing ethanol and alcohol levels. AR1018 achieved a 16.51% reduction in 3-methyl-1-butanol, whereas AR1038 exhibited a 27.32% increase in ester content compared to the control. Principal component analysis revealed distinct flavor characteristic between Huangjiu produced with AR1018 and AR1038, and sensory evaluation confirmed enhanced desirable attributes, especially for AR1038. This study highlights the potential of LAB starters in improving the flavor quality of rice wine and similar fermented beverages.

Investigation of the Effect of Fragrance-Enhancing Temperature on the Taste and Aroma of Black Tea from the Cultivar Camellia sinensis (L.) O. Kuntze cv. Huangjinya Using Metabolomics and Sensory Histology Techniques

Huangjinya has recently seen widespread adoption in key tea-producing areas of China, celebrated for its unique varietal traits. Its leaves are also used to produce black tea with distinctive sensory characteristics. The fragrance-enhancing (EF) process is essential in crafting Huangjinya black tea (HJYBT) and is significant in flavor development. However, the impact of EF on non-volatile metabolites (NVMs), volatile metabolites (VMs), and their interactions remains poorly understood. This study aims to investigate how EF temperatures (60 °C, 70 °C, 80 °C, 90 °C, and 110 °C) influence HJYBT flavor transformation. Quantitative descriptive analysis revealed that EF improved the color, aroma, and appearance of tea leaves. Moreover, after an EF temperature of 80 °C, the HJYBT exhibited lower bitterness and astringency, whereas floral, sweet, and fruity aromas became stronger. However, when EF temperatures exceeded 90 °C, a pronounced burnt aroma developed, with HJYBT at 100 °C exhibiting caramel and roasted notes. Partial least squares discriminant analysis indicated that geraniol and linalool contribute to floral and fruity aromas, while 2-ethyl-6-methyl-pyrazine, furfural, and myrcene are key volatiles for caramel and roast aromas. Heptanal, methyl salicylate, α-citral, 1-hexanol, and (E)-3-hexen-1-ol were found to modify the green and grassy odor. Overall, HJYBT treated at 80 °C EF exhibited the highest umami, sweetness, floral and fruity aromas, and overall taste, exhibiting the least astringency, bitterness, and green and grassy notes. These results provide a significant theoretical basis for enhancing HJYBT quality and selecting the optimal EF method.

Enhancement of flavor quality in oyster hydrolysate through fermentation with oyster-derived lactic acid bacteria

This study investigates the effect of autochthonous oyster-derived bacteria on mitigating the off-flavors in oyster hydrolysate (OPH) using flavoromics, microbiomics, and non-targeted metabolomics technologies. Results showed that the taste and odor sensory scores of oyster-derived lactic acid bacteria (LAB) fermentation were significantly better than those of commercial fermentation (p < 0.05), scoring 4.14 ± 0.47 and 4.23 ± 0.26, respectively (out of 5). Significant alterations were observed in volatile flavor compounds (VOCs) such as 5-nonanone, 2-undecanone, 3-octanol, 3,6-nonadien-1-ol, phenylethanol, and γ-decalactone. Non-volatile flavor metabolites were mainly represented by a rise in unsaturated fatty acids and a decrease in saturated fatty acids and bitter amino acids (Tyr and Arg). A total of 569 differential metabolites were identified, mainly involved in linoleic acid metabolism, glycerophospholipids, phenylalanine (Phe), tyrosine (Tyr), arginine (Arg), and proline (Pro). Lecithin, Tyr, Phe, histidine (His), Arg, and glutamine (Gln) were identified as flavor precursor compounds for oyster-derived LAB fermentation. High-throughput sequencing clarified the dominant role of oyster-derived LAB in influencing metabolites and precursors during fermentation. This study offers new insights into the mechanisms of flavor development in autochthonous bacteria-inoculated fermented shellfish.

Physicochemical investigations on molecular interactions of adenine with aqueous D-glucose/D-maltose solvent media at varying temperatures and compositions

Adenine derivatives are used in pharmaceuticals, and carbohydrates like D-maltose and D-glucose which are often used as excipients or stabilizers in drug formulations. Studying their interactions can help in optimizing drug formulations for stability and effectiveness. Further, understanding their interactions, provide insights into flavor development, food stability, and potential applications in food technology. In this regard, we have analysed the physicochemical properties of adenine in aqueous saccharide solvent media which can contribute to various fields, including biochemistry, pharmaceuticals, catalysis, and material science, with use for both basic research and practical applications. So, in this research work, physicochemical properties of adenine have been investigated in aqueous and mixed aqueous (0.05, 0.10 and 0.15) mol kg−1 D-glucose/D-maltose solvent media at discrete temperatures (293.15–313.15) K and experimental pressure (0.1 MPa). The experimentally determined physical properties such as density, velocity of sound, and viscosity have been utilized for the estimation of several parameters such as apparent molar volume (Vϕ), limiting apparent molar volume (V0ϕ), hydration number (nH), limiting apparent molar expansivity (E0ϕ), Hepler’s constant (∂E0ϕ/∂T)P, apparent molar isentropic compression (Kϕ,s), limiting apparent molar isentropic compression (K0ϕ,s), viscosity B-coefficients, transfer parameters and thermodynamic parameters of viscous flow (Δμ01, Δμ02, TΔS02 and ΔH02). Further, the Co-sphere overlap model has been employed for the analysis of varied probable interactions operating in the prepared systems. The obtained results signify that in all solution systems, the solute–solvent interactions are advancing with rising temperature and concentrations of saccharides. Also, the structure breaking tendency of adenine has been investigated via inference of Hepler’s constant data and positive values of dB/dT data for all the investigated systems. Moreover, the deduced apparent specific volume data evidently specify that adenine has sweet taste in water and different concentrations of chosen saccharides.

High-pressure processing for pickled crabs: Safety, quality and flavor assessment and correlation analysis of spoilage indicators

Pickled aquatic products are often susceptible to spoilage, which can significantly affect their edibility and flavor. This study aimed to improve the safety and quality aspects of pickled crabs by treated with high-pressure processing (HPP, 400 MPa for 5 min). The physical, chemical, microbiological, and flavor properties of the crabs before and after HPP were assessed, correlation and cluster analysis and orthogonal partial least squares discriminant analysis (OPLS-DA) were conducted on specific indicators influencing crab spoilage. The results indicated that HPP effectively reduced the total viable count, psychrophilic bacteria count (PBC), and Escherichia coliform (E. coli) count during storage at 4 °C (reduced by 30.61%, 36.72%, 100%, day 0, respectively; 19.02%, 21.95%, 100%, day 42, respectively). Moreover, HPP treatment reduced the total volatile basic nitrogen (TVBN) content (35.33 mg/100 g to 31.81 mg/100 g) and the production of putrescine (1858.7 mg/kg to 1293.04 mg/kg) and cadaverine (753.47 mg/kg to 422.08 mg/kg) in the end of storage stage, which extend the shelf life of the pickled crab by 12 days. Furthermore, the application of HPP facilitated the penetration of ethanol into the crab meat, thereby enhancing the development of the characteristic pickled crab flavor. The OPLS-DA analyses indicated that TVBN, TBA, and histamine as deteriorative factors for quality deterioration are key factors determining spoilage of crab, which are significantly correlated with other corruption products. This study provides valuable insights into improving the safety and flavor of crab products, establishing a theoretical basis for ensuring quality control throughout the production process.

Based on green synthesis, multisensory evaluations and molecular simulation approaches: Exploring the taste-enhancing characteristics and mechanisms of N-succinyl-L-leucine

N-Succinyl amino acids (N-Suc-AAs) are increasingly recognized for their potential as taste-active compounds. However, research into the green synthesis, taste-enhancing properties, and mechanisms of N-succinyl-L-leucine (N-Suc-Leu) remains limited. This study employed an enzymatic synthesis method, catalyzed by protamex and pancreatin, to produce N-Suc-Leu, with its structure confirmed. Multiple sensory techniques demonstrated that N-Suc-Leu markedly enhanced the umami, saltiness, and kokumi intensity, and prolonged the duration of umami by 25%. Sigmoid curve analysis further revealed the synergistic enhancement of N-Suc-Leu on the perceptions of umami and saltiness. Molecular docking and dynamics simulations revealed that N-Suc-Leu could bind with T1R1, T1R3, TMC4, and CaSR, enhancing the sensations of saltiness, umami, and kokumi, and bound closely to these receptors without altering their overall conformation. These findings offered a systematic explanation of the potential and mechanism of enzymatically synthesized N-Suc-Leu in enhancing taste and provided novel insights into potential strategies for the development and innovation of taste enhancers and food flavors.

Metagenomics-based insights into the microbial community dynamics and flavor development potentiality of artificial and natural pit mud

Strong-flavor Baijiu (SFB) production has relied on pit mud (PM) as a starter culture. The maturation time of natural PM (NPM) is about 30 years, so artificial PM (APM) with a shorter maturation time has attracted widespread attention. This study reveals the microbial and functional dissimilarities of APM and NPM, and helps to elucidate the different metabolic roles of microbes during substrate degradation and flavor formation. Significant differences in the microbial community were observed between APM and NPM, manifesting as variations in the abundance of core microorganisms. Total of 187 high-quality metagenome-assembled genomes (MAGs) were obtained based on the metagenomic binning technology, mainly including Firmicutes (n = 106), Bacteroidota (n = 15) and Chloroflexota (n = 14). Furthermore, the relative concentration of flavor compounds in 4-year APM was similar to those in 30-year NPM, but different from those in 100-year NPMs. Methanosarcina, Methanobacterium, Methanoculleus, Anaerolineae bacterium and Aminobacterium were the key bacteria responsible for the flavor differences. From a functional perspective, amino acid and carbohydrate metabolism were key functions of PM microbial, and showed differences between APM and NPM. Finally, substrate degradation and flavor generation pathways were found to exist in multiple microorganisms. Combine the relative abundance of microorganisms with the absolute abundance of enzymes, Clostridium, Lactobacillus, Petrimonas, Methanoculleus, Prevotella, Methanobacterium, Methanosarcina, Methanothrix, Proteiniphilum, Bellilinea, Anaerolinea, Anaeromassilibacillus, Syntrophomonas and Brevefilum were identified as the key microorganisms in APM and NPM.

The regulation of volatile flavor compounds in fermented meat products mediated by microorganisms: A review

Fermented meat products are widely consumed and favored by consumers because of their unique flavor and texture. Flavor formation is a complicated biochemical process, and microorganisms (mainly lactic acid bacteria, staphylococci, yeasts, and molds) play an essential role in flavor regulation. Elucidating the role of microorganisms in regulating the flavor formation of fermented meat products is critical for rationally designing microorganisms to improve the flavor quality of fermented meat products. Therefore, microorganisms, volatile compounds, and flavor-generating mechanisms of microorganisms in fermented meat products are summarized. This review also highlight correlations between microorganisms and flavor development and the effects of microorganisms on flavor development, which may provide important progress for the selection and application of microorganisms to improve the flavor of fermented meat products.

Proteomic profiles revealed enzymatic activities associated with the flavor formation of salted shrimp paste influenced by Bacillus subtilis K-C3 inoculation.

Enzymatic proteomic profiles were examined to comprehend the predominant enzymes involved in the flavor development of salted shrimp paste influenced by Bacillus subtilis K-C3 inoculation (Inoc), compared to those without inoculation (CON). Inoc showed greater proteolytic, lipolytic, and chitinolytic activities than CON (P < 0.05) throughout 30 days of fermentation, indicating B. subtilis's ability to accelerate the fermentation rate and render distinctive flavor profiles to shrimp paste. Among 50 differential abundance proteins (DAPs), 24 DAPs were identified as potential key regulating enzymes, with a P-value < 0.05 and |FC| > 0.50, indicating their significance and regulating capacity within specific metabolic pathways. Notably, 27 and 23 DAPs were up-regulated in Inoc and CON, respectively. Moreover, gene ontology (GO) enrichment analysis revealed that hydrolases, involved in carbohydrate metabolic processes and proteolysis, were the most differentiating pathways between Inoc and CON. Both samples exhibited different flavor profiles. A greater abundance of N-containing volatile compounds with a lower total abundance of aldehydes, ketones, alcohols, and acids could suggest a more favorable flavor in Inoc, compared to CON. Principal component analysis (PCA) revealed a positive correlation between L-ascorbate peroxidase, carboxypeptidase, and tripeptidyl peptidase sed2, with proteolytic and lipolytic activities in Inoc (P < 0.05). Meanwhile, acids and alcohols were positively correlated with CON. Therefore, B. subtilis inoculation could produce a distinctive flavor with a desirable sensory perception of shrimp paste regarding its ability to release extracellular enzymes/proteins. B. subtilis K-C3 inoculation could be suggested in the production of shrimp paste to improve its flavor characteristics.

The Addition of Glutamine Enhances the Quality of Huangjiu by Modifying the Assembly and Metabolic Activities of Microorganisms during the Fermentation Process.

In this study, the effects of adding glutamate (Glu), glutamine (Gln), aspartate (Asp), and asparagine (Asn) on the flavor formation of Huangjiu were investigated, and the effect of Gln concentration on the quality, microbial community structure, and flavor development of Huangjiu was further explored. Varied Gln concentrations influenced yeast growth, sugar utilization, microbial communities, and quality attributes. Additional Gln promoted yeast cell counts and sugar depletion. It increased the complexity of bacterial co-occurrence networks and reduced the impact of stochastic processes on assembly. Correlation analysis linked microorganisms to flavor compounds. Isolation experiments verified the role of Saccharomyces cerevisiae, Aspergillus chevalieri, Bacillus altitudinis, and Lactobacillus coryniformis in flavor production under Gln conditions. This research elucidated the microbiological mechanisms by which amino acid supplementation, especially Gln, enhances Huangjiu quality by modulating microbial metabolic functions and community dynamics during fermentation. This research is significant for guiding the production of Huangjiu and enhancing its quality.

Study on metabolic variation reveals metabolites important for flavor development and antioxidant property of Hainan Dayezhong black tea

To illustrate the development of chemical properties and characteristic flavor of Hainan Dayezhong black tea, the tea shoots under various manufacturing process were sampled and applied to targeted/widely-targeted metabolomic, transcriptomic, chemometric, and electronic sensory determinations. Totally, 2419 metabolites were identified in this study, of which 20 metabolites were selected as the biomarkers, mainly including amino acids, lipids, and pyrimidine derivatives. The metabolomic-transcriptomic integrated analysis indicated carbon fixation, flavonoid biosynthesis and amino acid metabolism were the major metabolic pathways over manufacturing process of Hainan Dayezhong black tea. The targeted metabolomic detection indicated the accumulations of free amino acids and reduction of total catechins, flavonol glycosides collectively contributed to the development of black tea taste; additionally, the antioxidative properties were decreasing along the production process. These results suggest that the tradeoff between bioactivity components and antioxidative capacity contribute to the characteristic flavor of Hainan Dayezhong black tea.

Tuning and modeling cheese flavor.

Flavor is a major sensory attribute affecting consumers' preference for cheese products. Differences in cheesemaking change the cheese microenvironment, thereby affecting cheese flavor profiles. A framework for tuning cheese flavor is proposed in this study, which depicts the full picture of flavor development and modulation, from manufacturing and ripening factors through the main biochemical pathways to flavor compounds and flavor notes. Taking semi-hard and hard cheeses as examples, this review describes how cheese flavor profiles are affected by milk type and applied treatment, fat and salt content, microbiota composition and microbial interactions, ripening time, temperature, and environmental humidity, together with packaging method and material. Moreover, these factors are linked to flavor profiles through their effects on proteolysis, the further catabolism of amino acids, and lipolysis. Acids, alcohols, ketones, esters, aldehydes, lactones, and sulfur compounds are key volatiles, which elicit fruity, sweet, rancid, green, creamy, pungent, alcoholic, nutty, fatty, and sweaty flavor notes, contributing to the overall flavor profiles. Additionally, this review demonstrates how data-driven modeling techniques can link these influencing factors to resulting flavor profiles. This is done by providing a comprehensive review on the (i) identification of key factors and flavor compounds, (ii) discrimination of cheeses, and (iii) prediction of flavor notes. Overall, this review provides knowledge tools for cheese flavor modulation and sheds light on using data-driven modeling techniques to aid cheese flavor analysis and flavor prediction.

Characterizing flavor development in low-salt Chinese horse bean-chili paste through integrated metabolomics and metagenomics

This study utilized metabolomics and metagenomics to investigate the microbial composition and functions in low- and high-salt Chinese horse bean-chili pastes (CHCPs). The results showed that 25 key metabolites were identified to distinguish the flavor attributes between the two samples. Leuconostoc was identified as the dominant microbiota in low-salt CHCP, while Pantoea prevailed in the high-salt CHCP. Compared to traditional high-salt fermentation, low-salt and inoculated fermentation promoted the increase in the relative abundances of Companionlactobacillus, Levilactobacillus, Tetragenococcus, Zygosaccharomyces and Wickerhamiella as well as the enrichment of carbohydrate and amino acid metabolic pathways, which contributed to the enhancement of characteristic flavor compounds. Further metabolic pathway reconstruction elucidated 21 potential microbial genera associated with the formation of key metabolites, such as Leuconostoc, Levilactobacillus, Pantoea, and Pectobacterium. This study may provide insights for optimizing the fermentation process and improving the flavor quality of low-salt CHCP and similar fermentation products. KeywordsLow-salt fermentationHight-salt fermentationChinese horse-bean chili pasteFlavor formationMetabolomicsMetagenomics