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.

Grains germinate, dry, and then undergo crushing before being combined with hot water to yield a sweet and viscous liquid known as wort. To enhance flavor and aroma compounds while maintaining a lower alcohol content, cold water is utilized during wort production without increasing its density. Recent years have witnessed a surge in demand for beverages with reduced alcohol content, reflecting shifting consumer preferences towards healthier lifestyles. Notably, consumers of low-alcohol beers seek products that closely mimic traditional beers. In response, batches of low-alcohol beer were meticulously crafted using a cold extraction method with room temperature water, resulting in a beer with 1.11% alcohol by volume (ABV). Sensory evaluations yielded a favorable score of 27 out of 50, indicating adherence to style standards and absence of major technical flaws. Furthermore, electronic taste profiling revealed a striking similarity between the low-alcohol beer and the benchmark International Pale Lager style, exemplified by commercial beers (5 and 0.03% ABV). Notably, the reduced-alcohol variant boasted lower caloric content compared to both standard and non-alcoholic counterparts. Consequently, the cold extraction approach emerges as a promising technique for producing low-alcohol beers within the International Pale Lager style, catering to evolving consumer preferences and health-conscious trends.

Consumer preferences for walnut products are largely determined by the flavors released during mastication. In this study, a peeled walnut kernel (PWK) model was established with oral parameters decoupled using a Hutchings 3D model. The model explored in vitro variations using head-space solid-phase microextraction-gas chromatography-mass spectrometry and intelligent sensory techniques. The fracture strength, hardness, particle size, adhesiveness, springiness, gumminess, and chewiness were significantly reduced during mastication. We identified 61 volatile compounds and found that 2,5-dimethyl-3-ethylpyrazine is a key component, releasing predominantly baking and milky notes. Glutamic acid, alanine, arginine, and sucrose were identified as the key compounds in taste perception. The method can help establish a mastication model for nuts and facilitate breakthroughs in the development of walnut products and processing methods.

Ethyl hexanoate and ethyl butyrate are indispensable flavor metabolites in strong-flavor Baijiu (SFB), but batch production instability in fermenting grains can reduce the quality of distilled Baijiu. Biofortification of the fermentation process by designing a targeted microbial collaboration pattern is an effective method to stabilize the quality of Baijiu. In this study, we explored the metabolism under co-culture liquid fermentation with Clostridium tyrobutyricum DB041 and Saccharomyces cerevisiae YS219 and investigated the effects of inoculation with two functional microorganisms on physicochemical factors, flavor metabolites, and microbial communities in solid-state simulated fermentation of SFB for the first time. The headspace solid-phase microextraction-gas chromatography-mass spectrometry results showed that ethyl butyrate and ethyl hexanoate significantly increased in fermented grain. High-throughput sequencing analysis showed that Pediococcus, Lactobacillus, Weissella, Clostridium_sensu_stricto_12, and Saccharomyces emerged as the dominant microorganisms at the end of fermentation. Co-occurrence analysis showed that ethyl hexanoate and ethyl butyrate were significantly correlated (|r| > 0.5, P < 0.05) with a cluster of interactions dominated by lactic acid bacteria (Pediococcus, Lactobacillus, Weissella, and Lactococcus), which was driven by the functional C. tyrobutyricum and S. cerevisiae. Mantel test showed that moisture and reducing sugars were the main physicochemical factor affecting microbial collaboration (|r| > 0.7, P < 0.05). Taken together, the collaborative microbial pattern of inoculation with C. tyrobutyricum and S. cerevisiae showed positive results in enhancing typical flavor metabolites and the synergistic effects of microorganisms in SFB.

Aromatic compounds serve as the primary source of floral and fruity aromas in sauce-flavor (Maotai flavor) baijiu, constituting the skeleton components of its flavor profile. Nevertheless, the formation mechanism of these compounds and key aroma-producing enzymes in sauce-flavor Daqu (fermentation agent, SFD) remain elusive. Here, we combined metagenomics, metaproteomics, metabolomics, and key enzyme activity to verify the biosynthesis pathway of aromatic compounds and to identify key enzymes, genes, and characteristic microorganisms in SFD. The results showed that the later period of fermentation was critical for the generation of aromatic compounds in SFD. In-situ verification was conducted on the potential key enzymes and profiles in various metabolites, providing comprehensive evidence for the main synthetic pathways of aromatic compounds in SFD. Notably, our results showed that primary amine oxidase (PrAO) and aldehyde dehydrogenase (ALDH) emerged as two key enzymes promoting aromatic compound synthesis. Additionally, two potential key functional genes regulating aromatics generation were identified during SFD fermentation through correlation analysis between proteins and relevant metabolites, coupled with in vitro amplification test. Furthermore, original functional strains (Aspergillus flavus-C10 and Aspergillus niger-IN2) exhibiting high PrAO and ALDH production were successfully isolated from SFD, thus validating the results of metagenomics and metaproteomics analyses. This study comprehensively elucidates the pathway of aromatic compound formation in SFD at the genetic, proteomic, enzymatic, and metabolomic levels, providing new ideas for the investigation of key flavor substances in baijiu. Additionally, these findings offer valuable insights into the regulatory mechanisms of aromatic compounds generation.

Evidence from in vitro and animal models has identified the pulmonary toxicity of flavors in electronic cigarettes (ECIGs); however, less is known from epidemiological studies about the effects of flavors in the respiratory health. This study examined the longitudinal association between exposure to ECIGs flavors and nocturnal dry cough among ECIGs users. A secondary analysis of data from the Population Assessment of Tobacco and Health Study (2014-2019) was conducted. The study population included adults who provided information (n = 18,925) for a total of 38,638 observations. Weighted-incidence estimates and weighted- generalized estimating equation models were performed to assess unadjusted and adjusted associations. The weighted incidence proportion (WIP) of nocturnal dry cough was significantly higher among current (WIP:16.6%; 95%CI 10.5, 21.2) and former fruit flavored ECIGs users (WIP:16.6%; 95%CI 11.3, 21.9) as compared to non-ECIGs users (WIP:11.1%; 95%CI 10.6, 11.6). Current ECIGs users of fruit flavors showed 40% higher risk of reporting cough than non-ECIGs users (aRR:1.40, 95%CI 1.01, 1.94). Former ECIGs users of multiple flavors and other flavors had 300% and 66% higher risk to develop cough, respectively (aRR:3.33, 95%CI 1.51, 7.34 and aRR:1.66, 95%CI 1.0.9, 2.51), relative to non-ECIGs users. We observed a significantly higher risk of developing nocturnal dry cough in the past 12 months in current and former ECIGs users of fruit flavors and in former ECIGs users of multiple flavors. To the extent that cough may serve as an early indicator of respiratory inflammation and potential disease risk, the association between ECIGs use and cough raises potential concerns.

β C-S lyases (β-CSLs; EC 4.4.1.8) are enzymes catalyzing the dissociation of β carbon-sulfur bonds of cysteine S-conjugates to produce odorant metabolites with a free thiol group. These enzymes are increasingly studied for their role in flavor generation in a variety of food products, whether these processes occur directly in plants, by microbial β-CSLs during fermentation, or in the mouth under the action of the oral microbiota. Microbial β-CSLs react with sulfur aroma precursors present in beverages, vegetables, fruits, or aromatic herbs like hop but also potentially with some precursors formed through Maillard reactions in cooked foods such as meat or coffee. β-CSLs from microorganisms like yeasts and lactic acid bacteria have been studied for their role in the release of polyfunctional thiols in wine and beer during fermentation. In addition, β-CSLs from microorganisms of the human oral cavity were shown to metabolize similar precursors and to produce aroma in the mouth with an impact on retro-olfaction. This review summarizes the current knowledge on β-CSLs involved in flavor generation with a focus on enzymes from microbial species present either in the fermentative processes or in the oral cavity. This paper highlights the importance of this enzyme family in the food continuum, from production to consumption, and offers new perspectives concerning the utilization of β-CSLs as a flavor enhancer.

2-phenylethanol (2-PE), an aromatic alcohol with a rose fragrance, is the second most widely used flavoring substance in the world. It is widely used in the cosmetic, food, and pharmaceutical industries. This paper introduces the chemical synthesis methods of 2-PE and the synthetic pathways in plants and microorganisms, summarizes the strategies to improve the microbial synthesis of 2-PE, reviews the research progress in de novo synthesis of 2-PE in microorganisms, and makes an outlook on the research prospects, aiming to provide a theoretical basis for the industrial production of 2-PE.

Counterfeit Baijiu has been emerging because of the price variances of real-aged Chinese Baijiu. Accurate identification of different vintages is of great interest. In this study, the combination of gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy was applied for the comprehensive analysis of chemical constituents for Maotai-flavor Baijiu. Furthermore, a novel data fusion strategy combined with machine learning algorithms has been established. The results showed that the midlevel data fusion combined with the random forest algorithm were the best and successfully applied for classification of different Baijiu vintages. A total of 14 differential compounds (belonging to fatty acid ethyl esters, alcohols, organic acids, and aldehydes) were identified, and used for evaluation of commercial Maotai-flavor Baijiu. Our results indicated that both volatiles and nonvolatiles contributed to the vintage differences. This study demonstrated that GC-MS and 1H NMR spectra combined with a data fusion strategy are practical for the classification of different vintages of Maotai-flavor Baijiu.

Chemosensory membrane proteins such as G-protein-coupled receptors (GPCRs) drive flavor perception of food formulations. To achieve this, a detailed understanding of the structure and function of these membrane proteins is needed, which is often limited by the extraction and purification methods involved. The proposed nanodisc methodology helps overcome some of these existing challenges such as protein stability and solubilization along with their reconstitution from a native cell-membrane environment. Being well-established in structural biology procedures, nanodiscs offer this elegant solution by using, e.g., a membrane scaffold protein (MSP) or styrene-maleic acid (SMA) polymer, which interacts directly with the cell membrane during protein reconstitution. Such derived proteins retain their biophysical properties without compromising the membrane architecture. Here, we seek to show that these lipidic systems can be explored for insights with a focus on chemosensory membrane protein morphology and structure, conformational dynamics of protein-ligand interactions, and binding kinetics to answer pending questions in flavor research. Additionally, the compatibility of nanodiscs across varied (labeled or label-free) techniques offers significant leverage, which has been highlighted here.