Release Of Volatile Compounds Research Articles

Effect of sulfur-containing groups on the susceptibility to spontaneous combustion of corrosion products in oil tanks

Sulfur-containing groups (SCG) may be an essential factor influencing the spontaneous combustion of oil tank corrosion products and triggering fire and explosion accidents. The effect of three SCG on the spontaneous combustion susceptibility of model compounds of tank corrosion products (MCTCP) were investigated. The results show that SCG causes the surface of MCTCP to produce cracks and become rough, which adsorbs more oxygen and SCG, enhancing its spontaneous combustion susceptibility. After the SCG addition, the MCTCP thermal susceptibility partial indicator values decreased. The apparent activation energy and the flammable volatile compound release temperature decreased significantly, which increased the spontaneous combustion susceptibility of MCTCP. In addition, SCG also increased the number of exothermic peaks in the self-ignition process of MCTCP. The exothermic peaks partly came from the oxidation of SCG, and the heat generated by the oxidation of SCG increased the spontaneous combustion susceptibility. Therefore, SCG may affect the spontaneous combustion susceptibility through three pathways: changing the microform and structure of MCTCP, thermal susceptibility parameters, and oxidative exothermic properties. The work assists in deepening the theory of the mechanism and influence factors of spontaneous combustion of corrosion products in oil tanks, and provide guidance for the prevention of such accidents.

Effects of steam explosion-modified rice bran dietary fiber on volatile flavor compounds retention and release of red date-flavored naan (ethnic specialty food of Xinjiang) during storage

This study explored the effects of steam explosion-modified rice bran dietary fiber (S-RBDF) on red date-flavored naan quality and flavor characteristics. The results revealed that the rheological properties of the dough were improved with the incremental addition of S-RBDF (0–5%). The microstructure revealed that adding an appropriate amount of S-RBDF (1–5%) enabled more starch granules to be embedded in the dough network. Notably, the addition of 5% S-RBDF resulted in naan with an optimum specific volume and texture, which consumers preferred. Additionally, gas chromatography–mass spectrometry analysis showed that adding S-RBDF to naan contributed to the retention and sustained release of pleasant volatile compounds (e.g. red date flavor, etc.), while inhibiting the development of unpleasant volatile compounds by delaying the oxidation and decomposition of lipids and preserving the antioxidant phenolic compounds, thus contributing to flavor maintenance of naan during storage. Overall, these results provided a foundation for developing high-quality flavored naan.

Warm Pressing of Organosilicon Polymer Toward Monolithic Ceramics

Warm pressing of organosilicon polymers is often challenging due to the formation of cracks due to release of volatile compounds during the warm pressing process. The focus of the present study is to warm press crosslinked SMP‐10 powders into crack‐free compacts and to pyrolyze them to get bulk SiC monoliths. Crack formation during warm pressing is addressed by optimizing the crosslinking temperature, and the loss of formability of the powders crosslinked at higher temperatures is overcome with the use of uncured polymer as a binder. The crosslinking temperature of the preceramic polymer plays a crucial role in developing crack‐free green bodies. The amount of binder used is varied to study its effect on the bulk density of the pyrolyzed product. The warm pressed green bodies pyrolyzed at 1400 °C result in the formation of bulk silicon carbide ceramics and are characterized using X‐ray diffractometer and FTIR spectroscopy. Warm pressing is performed at a lower temperature than reported in the literature, and this limits the incorporation of oxygen during the warm pressing.

Effect of pretreatment and activation conditions on pore development of coal-based activated carbon

Abundant pore volume and appropriate pore configuration are two crucial characteristics of high-performance carbonaceous adsorbents and catalysts. In this study, influences of pre-treatments (e.g., breaking, sieving and ash removal by acid) and activation conditions (e.g., activation time) on pore parameters (including BET surface area, pore diameter and pore hierarchy degree) of resultant activated carbon were systematically investigated. In addition, the difference between conventional carbonization-activation (i.e., the two-step preparation method) and one-step activation in pore development of activated carbons was revealed. The sample prepared by a 120-minute one-step activation exhibited a BET surface area high to 1038.1 m2/g and a pore hierarchy at 50.7 %. Based on the kinetics analysis using TGA reactor, reaction between the activator (i.e., CO2) and carbon matrix was enhanced in one-step activation, contributing to the generation of mesopores. Remarkably, a new indicator, Effective Activation Rate (EAR) was proposed to accurately describe the activation rate in one-step synthesis after decoupling the release of moisture and volatile compounds. The above conclusions provide guidance for flexibly regulating the pore configurations of activated carbons derived from natural precursors.

Recent advances and challenges in the interaction between myofibrillar proteins and flavor substances.

Myofibrillar proteins are an important component of proteins. Flavor characteristics are the key attributes of food quality. The ability of proteins to bind flavor is one of their most fundamental functional properties. The dynamic balance of release and retention of volatile flavor compounds in protein-containing systems largely affects the sensory quality and consumer acceptability of foods. At present, research on flavor mainly focuses on the formation mechanism of flavor components, while there are few reports on the release and perception of flavor components. This review introduces the composition and structure of myofibrillar proteins, the classification of flavor substances, the physical binding and chemical adsorption of myofibrillar proteins and volatile flavor substances, as well as clarifies the regulation law of flavor substances from the viewpoint of endogenous flavor characteristics and exogenous environment factors, to provide a theoretical reference for the flavor regulation of meat products.

Ultrasonic treatment enhanced the binding capacity of volatile aldehydes and pearl mussel (Hyriopsis cumingii) muscle: Investigation of underlying mechanisms

This study was aim to investigate the influencing mechanism of ultrasonic treatment on the interaction between volatile aldehydes and myosin. The results showed that when the mass concentration ratio of myosin to heptanal/hexanal was 1:0.3, ultrasonic treatment could enhance the binding capacity of myosin to heptanal/hexanal, especially the binding of myosin to hexanal. The entropy and enthalpy values of their interaction were negative, indicating that the interaction was mainly driven by hydrogen bond and van der Waals force. After ultrasonic treatment, the fluorescence wavelength of myosin-heptanal/hexanal complex was redshifted, the α-helix content was increased, while its roughness values, particle size and the polydispersity index were decreased. These demonstrated that ultrasonic treatment was conducive to myosin binding to heptanal/hexanal, thereby restraining the release of volatile flavor compounds from myosin, which could provide new insights for the regulation of volatile flavor compounds.

Performance and mechanism of benzene adsorption on ZnCl2 one-step modified corn cob biochar.

Utilizing cost-effective corn cob, zinc chloride-modified biochar was synthesized through one-step method for benzene adsorption from air. Study on impregnation ratio impact showed optimal benzene adsorption at ZnCl2:CC ratio of 1.5:1, with capacity reaching 170.53mgg-1. Characterization using BET, SEM, FTIR, and XPS was conducted. BET results indicated specific surface area of Zn1.5BC at 1260.63 m2g-1 and maximum pore volume of 0.546 m3g-1. SEM analysis revealed microporous-mesoporous structure in Zn1.5BC, marking significant improvement over original biomass. DFT pore size distribution and FTIR analysis suggested post-modification dehydration and elimination reactions, leading to volatile compound release, functional group reduction, and pore widening. XPS analysis showed decrease in O = C-OH content with increased impregnation ratio, enhancing biochar's π-π electron diffusion for benzene. Langmuir isotherm and pseudo-second-order kinetic models effectively described experimental data, indicating multilayer benzene adsorption on biochar controlled by complex physicochemical adsorption and pore diffusion. Adsorption condition assessment, including adsorption temperature (20-120℃) and benzene concentration in inlet phase (159.73-383.36 mg L-1), was performed. Yoon-Nelson model fitting indicated adsorption site loss at higher temperatures and reduced capture ability due to increased adsorbate molecule kinetic energy. Higher adsorbate concentrations aided adsorption molecule diffusion to biochar surface and internal pores, increasing adsorption rate and shortening equilibrium time. Overall, zinc chloride-modified biochar facilitates benzene adsorption through pore filling and π-π interactions, with pore filling as primary mechanism. Produced biochar shows excellent regeneration properties and reusability.

Headspace volatiles profiles of different spring varieties and a wild relative of wheat flour.

Volatile profiling was conducted on four wheat varieties Triticum aestivum cv. Chinese Spring (CS), Highbury (High), Paragon (Para), Pavon76 (Pav76), and one wild relative Triticum timopheevii (P95). Headspace solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to explore differences in flavor formation mechanisms in different flours before and after starch gelatinization. Solvent retention capacity (SRC) analysis revealed subtle differences in water absorption, gluten strength, and starch characteristics across wheat flour types. Rapid Visco Analysis (RVA) of whole wheat flour demonstrated significant variations in pasting properties among wheat varieties, with P95 exhibiting higher viscosities compared to CS and High potentially influenced by starch gelatinization, protein-starch interactions, and lipid content. Aroma contributions of P95 clustered positively in PCA plots, contrasting with the four main varieties, indicative of species-level differentiation. Furthermore, the study highlighted the roles of viscosity, protein structure, lipid content, and fatty acid composition in modulating the release and perception of volatile aroma compounds during heating. This study sheds light on how the distinct characteristics of wheat flour influence aroma profiles, revealing species-level differences and the pivotal role of physiochemical properties in shaping flavor development mechanisms.

Comparative study on mechanisms of gases release from Ca-alginate beads

Calcium alginate (Ca-alginate) beads have attracted considerable attention as carriers for the controlled release of volatile compounds due to their biocompatibility and tunable properties. This study aimed to compare the release of ethylene and carbon dioxide gas from Ca-alginate beads. Ca-alginate beads were prepared from a sodium alginate solution containing ethephon and calcium carbonate as the gas-forming agent. The resulting solution was then extruded into a calcium chloride solution. The gas release behavior was studied by monitoring the concentration of released gases over time using gas detectors. Extrusion tip diameter, alginate concentration and gas-releasing agent concentration were systematically varied to assess their effect on the gas release rate. The results indicated distinct release patterns for ethylene and carbon dioxide gas. Ethylene gas exhibited a relatively slower and sustained release, while carbon dioxide gas exhibited a more rapid release. Moreover, the bead size influenced the gas release, with larger beads displaying faster release rates for ethylene and carbon dioxide gas. The concentration of alginate also played a role in modulating the release kinetics, with higher alginate concentration resulting in slower gas release. The findings have implications for designing and optimizing Ca-alginate-based systems for agricultural applications, including plant hormone delivery and modified atmosphere packaging.

Investigating the mechanism of antioxidants as egg white powder flavor modifiers.

The uses of egg white powder (EWP) are restricted because of its odor. It is necessary to find a method to improve its flavor. In this paper, three different antioxidants - green tea extract (GTE), sodium ascorbate (SA), and glutathione (GSH) - were selected to modify the flavor. The physicochemical and structural properties of EWP were investigated to study the mechanism of the formation and release of volatile compounds. Antioxidants can modify the overall flavor of EWP significantly, inhibiting the generation or release of nonanal, 3-methylbutanal, heptanal, decanal, geranyl acetone, and 2-pemtylfuran. A SA-EWP combination showed the lowest concentration of 'off' flavor compounds; GTE-EWP and GSH-EWP could reduce several 'off' flavor compounds but increased the formation of geranyl acetone and furans. The changes in the carbonyl content and the amino acid composition confirmed the inhibition of antioxidants with the oxidative degradation of proteins or characteristic amino acids. The results of fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy provided structural information regarding EWP, which showed the release of volatile compounds decreased due to structural changes. For example, the surface hydrophobicity increased and the protein aggregation state changed. Antioxidants reduce the 'off' flavor of EWP in two ways: they inhibit protein oxidation and Maillard reactions (they inhibit formation of 3-methylbutanal and 2-pemtylfuran) and they enhance the binding ability of heat-denatured proteins (reducing the release of nonanal, decanal, and similar compounds). © 2023 Society of Chemical Industry.

Factors in Modulating the Potential Aromas of Oak Whisky Barrels: Origin, Toasting, and Charring.

In this study, the effects of origin (Chinese, France, and America), intensity of toasting, and degree of charring on the volatiles of oak whisky barrels were comprehensively investigated via liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) combined with multivariate statistical analysis. Results of principal component analysis (PCA) showed that the main oak-derived volatiles in oak were more influenced by origin and toasting than by charring. French oak had a higher content of volatile compounds than the other two origins, and this difference decreased with toasting and charring. The process of toasting and charring was important for the release of volatile compounds from oak. The content of most oak-derived volatiles increased with deeper toasting intensity, and the degree of charring promoted or inhibited the release of oak-derived volatiles. The volatile components in oak blocks were affected by the two-factor interaction of toasting and charring. Continuing the process of the charring of oak at a certain level of toasting may have an enhancing or diminishing effect on the content of different volatile compounds, depending on the circumstances.

Evaluating the role of operating temperature and residence time in the torrefaction of betel nutshells for solid fuel production

This research addresses the urgent need for sustainable bioenergy alternatives, specifically evaluating betel nutshells as potential replacements for conventional biomass materials like coconut and palm fibers. The objective of the study was to gauge the inherent bioenergy potential of betel nutshells through an investigation of torrefaction under varying conditions, specifically temperatures ranging from 200-300 °C and residence times between 20-60 minutes in an inert environment. In this study, proximate analyses were utilized to investigate essential characteristics including moisture content, volatile matter, ash content, and fixed carbon, while a bomb calorimeter was used to determine their higher heating values. Initial results indicated that untreated betel nutshells had higher heating values and compositional similarities to coconut and palm fibers, highlighting their potential as a bioenergy source. Advanced torrefaction processes, involving increased temperatures and extended residence times, raised the fixed carbon content and reduced moisture in betel nutshells, thereby optimizing their higher heating value. This improvement is attributed to the decomposition of covalent bonds in the biomass structures, leading to the release of volatile compounds and consequent reductions in both oxygen-to-carbon and hydrogen-to-carbon ratios. Remarkably, at an operating temperature of 300 °C and a residence time of 60 minutes, torrefied betel nutshells reached a higher heating value of 25.20 MJ/kg, marking a substantial 31.39 % increase compared to untreated specimens. This study conclusively positions betel nutshells, typically considered agricultural waste, as competitive alternatives to traditional biomass resources in the biofuel industry.

Enhancing pyrolysis of automobile shredder residue through torrefaction: Impact on heavy components formation in oil

Torrefaction of biomass is a well-known pretreatment method that can remarkably influence evolution of property of pyrolytic products in subsequent pyrolysis. Automobile shredder residue (ASR) is an important product in car recycling and it needs to be pretreated before recycling via pyrolysis. Nevertheless, how torrefaction impacts the composition and pyrolysis behaviours of ASR is still unknown, as ASR has a distinct composition from biomass. Thus, this study investigates the effect of torrefaction on the formation of heavy components in pyrolysis oil. ASR samples were torrefied from 240 °C to 330 °C and subsequently pyrolyzed from 600 °C to 800 °C with varied heating rates (ca. 80 °C /s and 0.17 °C /s). Results indicate that compared to raw ASR pyrolysis oil, torrefaction enhances the interaction between the volatile and semi-char, promoting the polymerization to form precursors of heavy components, thus the relative content of heavy components increases by >50% and heavy components containing heteroatoms decrease by >30% in the torrefied ASR pyrolysis oil, with the release of volatile heteroatom-containing compounds during torrefaction. More aliphatic heavy components are generated, reducing the overall aromaticity and degree of unsaturation of heavy components in the pyrolysis oil.

Volatile Compound Release from Oak Chips in Model Wine Media: Combined Influence of Toasting Degree, Size, Time of Contact, and Ethanol Content.

The effects of size, toasting degree, and time of contact on the release of volatile compounds from Quercus alba (L.) chips during a simulated fermentation and post-fermentative process were studied. The results obtained indicated that the large-size chips favored the release of furfural and furfuryl alcohol, while the small ones increased the concentration of cyclotene and maltol. The interaction between chip size and time of contact showed that the small-size chips are more sensitive to the increase of ethanol concentration for the extraction rate of some compounds (furfural, vanillin, maltol, cyclotene, whiskey lactones, and eugenol) compared to the large-size ones, increasing their concentrations at the end of maceration. The toasting degree of oak chips had a different influence on the volatile compounds studied. Cyclotene and guaiacol concentrations increased with the toasting intensity, whereas the extracted concentration of all compounds increased from light to medium-toasted chips, except for eugenol, and then decreased by further increasing the toasting level for 5-methylfurfural, whiskey lactones, eugenol, and only using high-level toasted chips for furfuryl alcohol, maltol, and vanillin. A possible protection effect of the chip size toward the possible degradation or volatilization losses of furfural for high toasting degrees was observed.

Identification of Volatile Compounds of Oil Palm Flower (<i>Elaeis guineensis</i> Jacq.) with Gas Chromatography and Mass Spectrometry Based on the Difference in Time

The pollination process in oil palm is assisted by the insect Elaeidobius kamerunicus, which occurs when male and female flowers bloom producing volatile compounds that act as attractants. This study aims to identify volatile compounds in oil palm flowers based on differences in times with gas chromatography mass spectrometry (GC-MS). The research steps include determining the time of the release of volatile compounds in oil palm flowers, extracted using steam distillation, and identification by GC-MS. There are different times of the release of volatile compounds for each type of oil palm flower. Three times by male flowers, at 08:00 am, 11:00 am and 14:00 pm, with the highest volatile compounds at 14:00 pm. Meanwhile, female flowers occurred at 09:00 am, 12:00 am and 15:00 pm, with the highest volatile compounds at 12:00 am. The results of the GC-MS analysis showed that 21 and 19 volatile compounds were identified, with a total of 38 different types. Estragole compounds were dominant in both types of flowers and did not show significant differences in the area sum values at each time of observation. These results indicated the importance of estragole compound for the pollination process in oil palm.

Capture modes evaluation of four flavor constituents in β-lactoglobulin by high-resolution mass spectrometry and molecular dynamics simulation approaches

Flavor retention and consumer receptivity of goat milk are strongly influenced by the interaction between flavor constituents and proteins. Few previous works suggested the impact of interactions between β-lactoglobulin (β-LG) and flavor constituents in goat milk on the release of volatile compounds. In present research, binding of β-lactoglobulin with four model flavor constituents, octanoic acid (OA), 4-methyloctanoic acid (MCA), 2-tridecanone (TO) and tert-butanol (TB) was deciphered. UHPLC-Q-Orbitrap high-resolution mass spectrometry results identified that all flavor molecules bound to β-lactoglobulin in the 1:1 stoichiometric ratio. Docking analysis of the lowest binding energy indicated that the strongest binding relationships between β-LG and MCA/OA/TB/TO were expected to be β-LG/TO > β-LG/MCA > β-LG/OA > β-LG/TB, which were spontaneous. Via molecular dynamic simulations, TO was located at hydrophobic cavity of β-barrel causing β-LG structure to further curl. The spatial direction of MCA began to gradually approach outer surface near Trp19-Arg124. OA was located in entrance of the hydrophobic core of each β-barrel. TB remained relatively stable at surface hydrophobic sac in the groove between β-barrel and α-helix. The effect of β-LG conformation was also evaluated by fluorescence spectroscopy, which was same to the molecular dynamics simulation. Present study may help to better understand the interaction mechanism of β-LG and flavor constituents and evaluate the ability of flavor compounds having a broad array of different functional groups to react with β-LG, which provided theoretical basis for quality maintenance of goat milk.

Oral Probiotics, Streptococcus salivarius K12 and M18, Suppress the Release of Volatile Sulfur Compounds and a Virulent Protease from Oral Bacteria: An In-Vitro Study.

To evaluate the inhibitory effects of Streptococcus salivarius K12 and M18 strains on the growth of six oral pathogens as well as their release of volatile sulfur compounds (VSCs), and whether these probiotics can inhibit the expression of arginine-specific gingipain A (RgpA), a protease secreted by Porphyromonas gingivalis. After six halitogenic oral pathogens (P. gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, and Eikenella corrodens) were cultured with or without S. salivarius K12 and M18, the concentration of two VSCs was measured. Moreover, the antimicrobial activity of S. salivarius K12 and M18 against these pathogens and the suppressive effect on RgpA release by P. gingivalis were assessed. In the co-culture of S. salivarius K12 or M18 with oral pathogenic bacteria, the growth of all six oral pathogens was significantly inhibited (p < 0.01). Additionally, S. salivarius K12 and M18 had an inhibitory effect on the production of the halitogenic substances H2S and CH3SH (p < 0.01) as well as the expression of P. gingivalis RgpA. Finally, we demonstrated that the addition of only culture supernatants of the two strains K12/M18 to oral pathogen cultures was sufficient to mimic the effects of K12/M18 co-cultures upon VSCs production and protease expression. S. salivarius K12 and M18 inhibited VSC release by all six of the major oral pathogens that were assayed and reduced the expression of RgpA.

Controlled volatile release from β-sitosterol-based oleogels based on different self-assembly mechanisms

This study examined how the self-assembly mechanisms of β-sitosterol-based oleogels influenced the release of volatile compounds. Microscopy, X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) measurements showed that the three β-sitosterol-based oleogels (β-sitosterol + γ-oryzanol oleogels (SO), β-sitosterol + lecithin oleogels (SL) and β-sitosterol + monostearate oleogels (SM)) had significant differences in their microstructures, which were formed via different self-assembly mechanisms. SO exhibited the highest oil binding capacity (OBC), complex modulus (G*) and apparent viscosity. Dynamic and static headspace analyses suggested that network structure of β-sitosterol-based oleogels affected the release of volatile components. SO showed the strongest retention effect, followed by SL and SM. The release of volatile compounds mainly related to structural strength and compositions of oleogels. These results indicated that β-sitosterol-based oleogels formed with different self-assembly mechanisms have the potential to serve as effective delivery systems for controlling the release of volatile compounds.

Effect of Fat to Lean Meat Ratios on the Formation of Volatile Compounds in Mutton Shashliks.

This study aimed to investigate the release of volatile compounds in mutton shashliks (named as FxLy, x-fat cubes: 0-4; y-lean cubes: 4-0) with different fat-lean ratios before and during consumption, respectively. In total, 67 volatile compounds were identified in shashliks using gas chromatography/mass spectrometry. Aldehyde, alcohol, and ketone were the major volatile substances, accounting for more than 75% of the total volatile compounds. There were significant differences in the volatile compounds of mutton shashliks with different fat-lean ratios. With the increase of the fat content, the types and content of volatile substances released also increase. However, when the percentage of fat exceeded 50%, the number of furans and pyrazine, which were characteristic of the volatile compounds of roasted meat, was decreased. The release of volatiles during the consumption of mutton shashliks was measured using the exhaled breath test and the results showed that adding an appropriate amount of fat (<50%) helps to enrich the volatile compound components in the mouth. However, shashliks with higher fat-lean ratios (>2:2) shorten the mastication duration and weaken the breakdown of bolus particles in the consumption process, which is not conducive to the release potential of volatile substances. Therefore, setting the fat to lean ratio to 2:2 is the best choice for making mutton shashliks, as it (F2L2) can provide rich flavor substances for mutton shashliks before and during consumption.

PH-responsive nanofibrous membrane fabricated from gelatin and red radish anthocyanins for meat spoilage monitoring

A novel green pH-responsive nanofibrous membrane was developed based on gelatin and red radish (Raphanus sativus L.) anthocyanin extract (RRAE) through electrospinning fabrication. The varieties of color on the pH-responsive nanofiber, as observed by the naked eye, can be changed instantly into unique colors at different pHs. The fibrous mats were characterized by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermal gravimetric analysis (TGA), and mechanical tensile testing. Investigation of the stability of the membrane sensor revealed that this nanofiber was tolerant over a wide range of temperatures, and the color on the fiber mats was initially stable after 20 days of storage at room temperature. In addition, pH-responsive nanofiber was applied for real-time meat spoilage monitoring. The results indicated that their color changed with a change in pH as a result of the release of volatile basic compounds due to the spoilage of meat. Thus, the pH-responsive nanofibrous membrane developed in this study can be potentially utilized for food packaging applications.