Formation Of Volatile Compounds Research Articles

The Influence of Cooking Methods and Muscle on Beef Aroma Profile and Consumer Satisfaction: Insights from Volatile Compound Analysis

The objective of this study is to determine the effect of two distinct cooking techniques, namely roasting and stewing, on the formation of volatile compounds in various beef muscles (Semimembranosus, Biceps femoris, and Rectus femoris) and how this relates to consumer acceptance. The research employs the concept of volatile “marker” compounds to discern the influence of cooking techniques on the flavor profile of beef. Eighteen “marker compounds” were selected to represent a number of the mechanisms of formation and quantified in beef subjected to two different cooking methods. While no statistically significant differences were observed in consumer evaluations between the two cooking methods, notable disparities emerged in the consumer assessments of specific muscle cuts. Notably, the Rectus femoris muscle received the highest ratings (p < 0.05) among other evaluated muscles. The utilization of Solid-Phase Microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods for the analysis of volatile “marker compounds” in beef proved effective in highlighting significant differences in flavor compound classes between cooking methods, and these differed between muscles. The main effect was of the cooking method with stewed beef aroma having approximately 39× more dimethyl trisulphide, 9× more dimethyl disulphide, 7× more pentanal, 3× more hexanal, and twice as much benzaldehyde and 2-methylthiophene. Dimethyldisulphide, dimethyltrisulphide, hexanal, and heptanal, therefore, emerged as characteristic volatile compounds associated with the stewing cooking technique, suggesting their potential as markers for lipid and other oxidation reactions. This work indicates that certain lipid oxidation compounds, Strecker aldehydes, and sulfur compounds can be markers for the undesirable and/or desirable flavors of cooked beef, but that this depends on the cooking method chosen. It shows that flavor differences may be understood through the analysis of volatile flavor compounds in association with palatability and other chemical measurements.

Flavor Precursor and Volatile Compounds Formation of Unfermented Cocoa Beans Hydrolyzed by Papain

Fermentation is notably crucial stage in the production of cocoa flavor precursors. Nevertheless, some cocoa plantations in Indonesia skip fermentation as the raw material is relatively small, and the fermentation period is extremely long. This study aimed to improve the flavor precursors in unfermented cocoa beans (var. forastero). Unfermented cocoa beans were hydrolyzed using papain at different concentrations and incubation times. The conditions to obtain the highest degree of hydrolysis were 3.3 U/mL (papain conc.) at 10 h incubation. After papain treatment, it exhibited lower reducing sugars and polyphenol content than unfermented cocoa beans. Besides, hydrophobic amino acids such as phenylalanine, valine, leucine, and isoleucine was increased. After roasting, volatile compounds for chocolate aroma were also presented. However, pyrazines, aldehydes, and esters, were still less than those in fermented cocoa beans. The results proved that the papain hydrolysis of unfermented cocoa beans can improve their flavor precursors and volatile compounds.

The potential meat flavoring derived from Maillard reaction products of rice protein isolate hydrolysate-xylose via the regulation of temperature and cysteine

Maillard reaction products (MRPs) derived from rice protein isolate hydrolysate and D-xylose, with or without L-cysteine, were developed as a potential meat flavoring. The combined impact of temperature (80–140 °C) and cysteine on fundamental physicochemical characteristics, antioxidant activity, and flavor of MRPs were investigated through assessments of pH, color, UV–visible spectra, fluorescence spectra, free amino acids, volatile compounds, E-nose, E-tongue, and sensory evaluation. Results suggested that increasing temperature would reduce pH, deepen color, promote volatile compounds formation, and reduce the overall umami and bitterness. Cysteine addition contributed to the color inhibition, enhancement of DPPH radical-scavenging activity and reducing power, improvement in mouthfulness and continuity, reduction of bitterness, and the formation of sulfur compounds responsible for meaty flavor. Overall, MRPs prepared at 120 °C with cysteine addition could be utilized as a potential meat flavoring with the highest antioxidant activity and relatively high mouthfulness, continuity, umami, meaty aroma, and relatively low bitterness.

Characterization of lipids and volatile compounds in boiled donkey meat by lipidomics and volatilomics.

Lipids are crucial substances for the formation and retention of volatile compounds (VOCs). The lipid and VOC profiles of boiled donkey meat were investigated by lipidomics and volatilomics. In total, 4277 lipids belonging to 39 subclasses were identified, comprising 26.93% triglycerides (TGs), 15.74% phosphatidylcholins (PCs), and 9.40% phosphatidylethanolamines. The relative percentage of TG in the meat significantly decreases (p<0.001) from 0 to 40min, after which there is no significant change, whereas PCs, sphingomyelins, and methyl phosphatidylcholines (MePCs) show the opposite trend. TG(16:1_18:1_18:2) and TG(16:0_16:1_18:2) appear to be key lipids for retaining VOCs in boiled donkey meat. Furthermore, PC(18:3e_16:0) and MePC(31:0e) were found to be potential markers for discriminating donkey meat. A total of 83 VOCs were detected, including 25.30% aldehydes, 18.07% hydrocarbons, 14.46% ketones, and 13.25% alcohols. Eleven characteristic VOCs with relative odor activity values >1 were identified as the predominant flavor compounds in boiled donkey meat, mainly hexanal and 1-octen-3-ol. Of the 258 differential lipids, 72 of them, especially polyunsaturated-fatty acid-rich lipids, are the main contributors to the formation of VOCs. Together, the key lipids for retention and formation of VOCs in donkey meat were revealed, providing a theoretical basis for VOC regulation.

Lipid changes and volatile compounds formation in different processing stages of dry-cured Spanish mackerel

Abstract This study delves into the alterations in lipids and major flavor compounds occurring throughout various drying stages (raw fish, dry-cured for 4 d, 8 d, and 12 d) of dry-cured Spanish mackerel (DCSM) and elucidates the mechanism behind their formation. The findings exhibit a notable reduction in phospholipid (PL), triacylglycerol (TAG), heptanal, t-2-hexenal, and dimethyl disulfide contents in the samples observed four days before processing. The peroxide value (POV) and thiobarbituric acid reactive substances (TBARS) witnessed a significant surge after 4-8 days, concomitant with the generation of numerous volatile compounds, encompassing alcohols, aldehydes, and ketones. Substantial quantities of 2-methylbutyraldehyde, thiazole, butyl acetate, and trimethylpyrazine emerged during the 8-12 days processing phase. Furthermore, C18:1n-9, C20:5n-3, and C22:6n-3 demonstrated noteworthy correlations with the development of 21 compounds. Principal Component Analysis (PCA), grounded in lipid and volatile compound content, adeptly classified the DCSM drying process into lipolysis and flavor preparation (0-4 d), lipid oxidation and flavor formation (4-8 d), and maturation (8-12 d). The ripening stage played a crucial role in shaping the comprehensive flavor profile. This study offers valuable insights to enhance the traditional DCSM flavor processing and regulation.

Quantification of Byproduct Formation from Portable Air Cleaners Using a Proposed Standard Test Method.

In response to the COVID-19 pandemic, air cleaning technologies were promoted as useful tools for disinfecting public spaces and combating airborne pathogen transmission. However, no standard method exists to assess the potentially harmful byproduct formation from air cleaners. Through a consensus standard development process, a draft standard test method to assess portable air cleaner performance was developed, and a suite of air cleaners employing seven different technologies was tested. The test method quantifies not only the removal efficiency of a challenge chemical suite and ultrafine particulate matter but also byproduct formation. Clean air delivery rates (CADRs) are used to quantify the chemical and particle removal efficiencies, and an emission rate framework is used to quantify the formation of formaldehyde, ozone, and other volatile organic compounds. We find that the tested photocatalytic oxidation and germicidal ultraviolet light (GUV) technologies produced the highest levels of aldehyde byproducts having emission rates of 202 and 243 μg h-1, respectively. Additionally, GUV using two different wavelengths, 222 and 254 nm, both produced ultrafine particulate matter.

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

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

Influence of the reflective silver coating layer on the long-term durability of Ag nanoparticles/polymer assembly

In this paper, we have sought to determine if a reflective silver coating layer could prevent the degradation of a silver/acrylate polymer assembly and the loss of its optical property in an environment simulating sunlight. For this purpose, a multiscale approach from micro(nano) scale to macroscopic scale was applied. The overcomes of this investigation revealed that the metallic coating did not act as a barrier against photooxidation of the polymer matrix and silver nanoparticles, on contrary, catalysed the degradation process. The multiscale approach showed that not only the matrix underwent structural and architectural changes with the formation of oxidative products and volatile compounds due to chain scission reaction, but also the alteration of the metallic layer with the formation of defects at its surface, evidenced by optical and atomic force microscopy.An original approach using photo-DSC allowed to monitor the thermo-optical properties of the material. It pointed out the loss of the optical properties of the silver/polymer assembly during irradiation that was linked to the degradation of the acrylate polymer.

Changes in Chemical Composition of Lentils, Including Gamma-Aminobutyric Acid and Volatile Compound Formation during Submerged and Solid-State Fermentation with Pediococcus acidilactici.

The aim of this study was to evaluate and compare the characteristics of non-treated and fermented [via submerged (SMF) and solid-state (SSF) fermentation using Pediococcus acidilactici] lentils (Lens culinaris) grown either in pure stands (L) or relay intercropped with winter rye (LR). It was observed that the lentils were suitable substrate for lacto-fermentation. Most of the free amino acid concentrations increased in lentils after both fermentations. The highest concentration of γ-aminobutyric acid was found in SSF LR samples. However, fermentation led to higher biogenic amines (BA) content in lentils. The most abundant fatty acid in lentils was C18:2. SSF lentils showed more complex volatile compound (VC) profiles (with between nine and seventeen new VCs formed), whereas, in SMF samples, between two and five newly VCs were formed. When comparing lentil grown types, L contained significantly higher concentrations of Na, K, Ca, P, Mn, and Se, while LR contained significantly higher concentrations of Fe and Ni. To sum up, fermentation with lactic acid bacteria (LAB) contributed to the improved biological value of lentils; still, the quantity of BA needs to be considered. Further investigations into the P. acidilactici metabolism of certain compounds (such as phenolic and antinutritional compounds) in lentils during fermentation ought to be carried out.

Dynamic changes in metabolomics and flavoromics during industrial scale fermentation of Chinese traditional soy sauce

Flavor substances are crucial to the quality of soy sauce and closely related to the intermediate metabolites. This study systematically explored the dynamic changes in physicochemical characteristics, metabolomics and flavoromics during traditional Chinese soy sauce fermentation. The results indicated that the amino acid nitrogen gradually increased to 0.95 g/100 mL on the 13th day and then stabilized, and the changes of reducing sugars increased to 66.40 mg/mL on the 7th day and then slowly decreased. A total of 90 volatile compounds and 1172 non-volatile metabolites were detected. In the early fermentation period (1–7 day), alcohols, aldehydes and ketones were the main volatile compounds, but as fermentation proceeded, phenols and esters gradually accumulated. The total content of volatile compounds, mainly alcohols and phenols, reached the highest value on the 23rd day. Non-volatile metabolites were mainly amino acids, organic acids, lipids and carbohydrates, and the content and types of varied with fermentation time. KEGG analysis indicates there were significant changes in the proline and arginine metabolism in the middle and late periods (7–28 day) compared to the early fermentation period. Correlation analysis indicating a delicate balance between the transformation of metabolites and the formation of volatile compounds in traditional Chinese soy sauce.

Risk assessment and toxicity effects of materials used during additive manufacturing with FDM technology

This paper discusses the potential of additive printing, the risks it poses to users' health (including 3D printer operators) and the effects of chemical substances released during the printing based on the available in vitro and in vivo studies. It was shown that substances emitted during printing with the commonly used acrylonitrile butadiene styrene (ABS) filament in additive manufacturing might have carcinogenic, hepatotoxic and teratogenic effects, as well as toxic effect on the respiratory system. The latest research on the mechanism of formation of particles and volatile organic compounds (VOCs) during 3D printing, the parameters affecting their potential emission, and trends in reducing these hazards are indicated. The need for the design of more environmentally friendly and less emissive printing materials, as well as strategies for prevention and individual and collective protection measures are emphasized. Users of 3D printers should be familiar with all possible aspects of the threats associated with the printing process. Insufficient data on direct exposure to chemicals and particles released during the use of filaments makes it difficult to build awareness of safe working practices. Of particular concern is the health impact of emitted chemicals and particles from thermally treated materials in one of the most popular technologies for 3D printing, i.e., fused deposition modelling. Exposure of the users to, for example, plasticizers added to filaments occurs through a variety of routes, by absorption through the skin, by inhalation or ingestion. Available epidemiological data, as well as current experimental works, indicate that such exposure is a high risk of cardiovascular diseases, atherosclerosis in adults, and cardiac problems and metabolic disorders in children. This review, by identifying potential risk factors, may contribute to reducing the health loss of printer users and improving working conditions and safety, especially in enterprises where additive manufacturing technology is used. Med Pr Work Health Saf. 2024;75(2).

Monitoring of changes in the concentration of volatile organic compound in beef irradiated with accelerated electrons

The need to develop safe methods for radiation processing of food products to improve their quality and extend their shelf life stimulates new scientific research aimed at increasing their effectiveness. Oxidation of lipids and proteins occurred under the impact of ionizing radiation in products with a high fat and water content, such as chilled meat and fish products, leads to the formation of volatile organic compounds in the product thus giving it a specific smell and taste. During storage, biochemical processes associated with microbial enzymatic activity and auto-oxidation develop in processed refrigerated products. These processes also modify the volatile organic compounds, which affect the organoleptic properties of the product. The method of gas chromatography-mass spectrometry was used to study the behavior of volatile compounds identified in irradiated beef samples both immediately after irradiation and four days later to determine the effective dose range for the radiation processing of beef. Monitoring of the content of volatile compounds in beef samples irradiated by 1-MeV electrons within a dose range from 0.25 to 5 kGy showed that the content of certain alcohols, aldehydes, and alkanes exhibited pronounced dose- and time-dependent character. The developed mathematical model describes the dependence of the concentration of volatile compounds identified immediately after irradiation in beef samples on the irradiation dose. The model is based on the simultaneous occurrence of two competing processes: the decomposition of compounds due to their oxidation and accumulation due to oxidation of other compounds after exposure to ionizing radiation. The results obtained revealed that the effective dosage range of radiation treatment lies between 250 and 1000 Gy.

Identification of dynamic changes in volatile compounds and metabolites during the smoking process of Zhenba bacon by GC-IMS combined metabolomics

Zhenba bacon is a traditional cured bacon product with a rich history that originated from Zhenba County, Shaanxi Province. This study aimed to investigate the patterns of volatile compound formation and changes in metabolites during the smoking process in Zhenba bacon. Firstly, the sensory properties and physicochemical properties of Zhenba bacon were analyzed. Gas chromatography-ion mobility spectrometry (GC-IMS) and nontargeted metabolomics technology were used to analyze Zhenba bacon from different smoking stages. The results show a gradual increase in the sensory acceptance and volatile flavor compounds such as aldehydes, ketones, and esters with the prolongation of smoking of Zhenba bacon. LC–MS analysis identified 191 co-expressed differentially metabolites, with amino acid and lipid metabolism being the main metabolic pathways according to KEGG enrichment analysis. Temporal expression analysis of bacon metabolites at each stage revealed a decrease in harmful steroid hormones such as cortisone and an increase in amino acids and lipid metabolites, such as arginine, lysine, acid, and cholesterol, that contribute to the flavor of bacon. In summary, duration of smoking increased, the amount of flavor substances in Zhenba bacon gradually increased, and the safety and quality of bacon reached the optimal level after 32 days of smoking. This study provides valuable insights into the dynamic changes in volatile flavor compounds in Zhenba bacon and establishes a theoretical foundation for quality control during its production.

Changes in volatile compounds and lipid oxidation in various tissues of Nile tilapia (Oreochromis niloticus) during ice storage.

Changes in the lipid oxidation and volatile compounds of a variety of tilapia tissues (Oreochromis niloticus) including the muscle, gills, and skin during ice storage were investigated by evaluating peroxide values (PVs), lipoxygenase (LOX) activity, fatty acid (FA) composition, and volatile substances. LOX activity and PV were determined in the gills, skin, and muscles throughout 9 days of storage in ascending order to the extended storage time. The highest level of LOX activity was found in the gills, whereas the highest PV was determined in the skin. FA content of all tissues decreased during the storage period. Oleic acid was the predominant monounsaturated fatty acid, whereas linoleic acid and docosahexaenoic acid were the main polyunsaturated fatty acids and omega-3 in all tissues. The fish gills were shown to have the highest level of volatile compounds followed by the skin and muscle, based on headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. Principal component analysis indicated gradual changes in the volatile compound composition with increasing storage time. 2-Butanone and nonanal in the muscle, 6-methyl-2-heptanone and 2-nonenal in the gills, and 1-heptanol, and 1-nonanol in the skin were found to be the potential freshness indicators. In addition, hexanal could be a general potential marker for measuring the degree of lipid oxidation in all tissues. PRACTICAL APPLICATION: Understanding the volatile compound formation related to lipid oxidation within storage time at various tissues of tilapia could be critical to the side-stream processing to yield the desired quality.

Optimization and validation of an HS-SPME/GC-MS method for determining volatile organic compounds in dry-cured ham.

The formation of volatile organic compounds (VOCs) in dry-cured ham is a result of different biochemical and enzymatic processes. Moreover, accurately quantifying these VOCs is challenging since ham is a complex matrix, which contains compounds from various chemical families and a wide range of volatilities of different molecular masses. In this study, we systematically optimized and validated an analytical method for quantifying VOCs in dry-cured ham using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Optimal SPME conditions were determined through both an experimental procedure (one-factor-at-a-time) and response surface methodology (RSM), revealing that a 60-min equilibration at 70°C, a 60-min extraction at the same temperature, and a 4-min desorption time at 250°C provided the most favorable results. To enhance quantitation, twelve multiple internal standards (ISTDs) were employed to address and improve the quantitation of the 12 VOCs. Method validation covered aspects of linearity, limits of detection (LOD: 0.03-1.13 mg kg-1), limits of quantitation (LOQ: 0.09-3.41 mg kg-1), and working ranges (0.01-19.1 mg kg-1). The practical application of this optimized method was demonstrated by analyzing dry-cured ham samples (n = 4), sourced from the Slovenian market. The initial statistical evaluation indicates that different types of dry-cured hams can be differentiated (with an 83.1% of accuracy) according to their aromatic profile. However, a larger sample size would be required to provide a more comprehensive assessment.

Effects of fatty acid hydroperoxides produced by lipoxygenase in wheat cultivars during dough preparation on volatile compound formation

The formation of volatile compounds affects the flavor of processed wheat flour products. Herein, the effects of the composition of fatty acid hydroperoxides and the differences in the antioxidant contents among wheat cultivars on the flavor of wheat flour products were clarified. For this purpose, the volatile compounds in wheat flour doughs, LOX activity, fatty acid hydroperoxide composition from fractionated LOX, and antioxidant content were analyzed. Norin61 exhibited a high LOX activity and 9-fatty acid hydroperoxide production. Unsaturated aldehydes derived from 9-fatty acid hydroperoxides contributed significantly to the volatile compound profile of Norin61. Moreover, the lowest lutein content was observed in Norin61 among the analyzed cultivars. The LOX activity and composition of the fatty acid hydroperoxides produced by LOX affected the production of volatile compounds, whereas carotenoids had a suppressive effect. This study provides useful information for product design with the desired flavor for developing various processed wheat flour products.

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

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

Profiling volatile compounds in fresh leaves of 22 major oolong tea germplasm cultivated in Fujian of China

Tea is highly esteemed by consumers due to its distinct aroma and the abundance of nutrients that contribute to human well-being. While volatile compounds in fresh tea leaves serve as the essential foundation for tea aroma, the understanding of cultivar-specific aroma constituents and their genetic regulation remains a research gap. In this study, we extracted and profiled the volatile compounds in fresh leaves from 22 major oolong tea cultivars using gas chromatography-mass spectrometry. A total of 140 volatile compounds were identified, of which 61 were consistently found in all tea cultivars. The volatile profiles of the 22 tea cultivars exhibited considerable dissimilarity, with several distinct cultivar-specific volatiles identified. Subsequent analysis of nonadditive volatiles in tea hybrids revealed a noteworthy positive mid-parent heterosis (MPH) in ‘Mingke 1’ (also known as ‘Jinguanyin’) and ‘Huangmeigui’. Comprehensive heterosis across various volatile compounds was also documented. Our study elucidated the composition of volatile compounds in the fresh leaves from the major oolong tea cultivars and provided an extensive exploration of volatile heterosis in tea plants. These cultivar-specific volatile variations will offer essential insights for enhancing the genetic aspects of tea aroma flavor and deepen our understanding of the molecular mechanisms underlying volatile compound formation in fresh tea leaves.

Enhancement of fermented sausage quality driven by mixed starter cultures: Elucidating the perspective of flavor profile and microbial communities

The metabolic activities of microorganisms play a crucial role in the quality development of fermented sausage. This study investigated the effect of inoculation with different combinations of starter cultures (Lactiplantibacillus plantarum YR07, Latilactobacillus sakei L.48, Staphylococcus xylosus S.14, and Mammaliicoccus sciuri S.18) on the quality of sausages. Inoculation with mixed starter cultures promoted protein degradation to generate amino acids and the conversion to volatile compounds, which enhanced the flavor development in fermented sausages. The bacterial community analyses demonstrated that the inoculation of mixed starter cultures could inhibit the growth of spoilage and pathogenic bacteria, thereby reducing the total content of biogenic amines. The correlation analysis between the core bacteria and characteristic volatile compounds revealed that fermented sausages inoculated with Lactobacillus and coagulase negative staphylococci exhibited significant positive correlations with the majority of key characteristic volatile compounds. In four treatments, inoculation with L. plantarum YR07 and M. sciuri S.18 greatly promoted the formation of characteristic volatile compounds (3-hydroxy-2-butanone, hexanal, and 1- octen-3ol). Therefore, the combined inoculation of L. plantarum YR07 and M. sciuri S.18 is promising to enhance fermented sausage's flavor profile and safety.

Effect of 2-alkenals on the Maillard reaction of cysteine-glucose: Initial stage intermediate formation and flavor compound generation pathways

To explore the effect of (E)-2-hexenal, (E)-2-heptenal, and (E)-2-octenal on the initial Maillard reaction pathways and formation of volatile compounds, cystine-Amadori and thiazolidine derivatives were synthesized, identified by UPLC‒TOF/MS and NMR, and quantified by UPLC‒MS/MS. Depending on the concentration of the intermediates, the reactivity of the 2-alkenals in the reaction became weaker with the extension of the carbon chain. According to the content of 87 volatile compounds detected by GC‒MS‒O, the Maillard reaction was inhibited by decreasing the number of carbon atoms of 2-alkenal. The carbohydrate module labeling method demonstrated that the 2-ethylthiophene, 2-propylthiophene, and 2-butylthiophene carbon backbones were derived from 2-alkenal. Particularly, it was found for the first time that 2,3-dihydro-1 H-indole could be generated from both the intact skeleton of glucose and the degradation product of 2-alkenal. Notably, we proposed a route for the formation of 2-butanoylthiophene starting from (E)-2-octenal which was further converted to 2,4-octdienal. This study can be used as guidance in improving the flavor of meat and savory flavorings.