Formation Of Volatile Products Research Articles

Formation of Inorganic Sulfate and Volatile Nonsulfated Products from Heterogeneous Hydroxyl Radical Oxidation of 2-Methyltetrol Sulfate Aerosols: Mechanisms and Atmospheric Implications.

Chemical transformation of 2-methyltetrol sulfates (2-MTS), key isoprene-derived secondary organic aerosol (SOA) constituents, through heterogeneous hydroxyl radical (•OH) oxidation can result in the formation of previously unidentified atmospheric organosulfates (OSs). However, detected OSs cannot fully account for the sulfur content released from reacted 2-MTS, indicating the existence of sulfur in forms other than OSs such as inorganic sulfates. This work investigated the formation of inorganic sulfates through heterogeneous •OH oxidation of 2-MTS aerosols. Remarkably, high yields of inorganic sulfates, defined as the moles of inorganic sulfates produced per mole of reacted 2-MTS, were observed in the range from 0.48 ± 0.07 to 0.68 ± 0.07. These could be explained by the production of sulfate (SO4 •-) and sulfite (SO3 •-) radicals through the cleavage of C-O(S) and (C)O-S bonds, followed by aerosol-phase reactions. Additionally, nonsulfated products resulting from bond cleavage were likely volatile and evaporated into the gas phase, as evidenced by the observed aerosol mass loss (≤25%) and concurrent size reduction upon oxidation. This investigation highlights the significant transformation of sulfur from its organic to inorganic forms during the heterogeneous oxidation of 2-MTS aerosols, potentially influencing the physicochemical properties and environmental impacts of isoprene-derived SOAs.

Synthesis of phenyl esters 2-oxo-2H-1-benzopyran-3-carboxylic acids as promising antimicrobial agents

Corresponding chloroanhydrides were synthesized by the interaction of coumarin-3-carboxylic and 6-methoxycoumarin-3-carboxylic acids with an excess of thionyl chloride under heating. Due to the quantitative yields and the formation of volatile products within the reaction, chloroanhydrides were used without additional purification in acylation of substituted phenols for the synthesis of phenyl esters of 2-oxo-2H-1-benzopyran-3-carboxylic acids. The reaction was carried out by heating in anhydrous dioxane environment in the presence of pyridine as a catalyst. The structure of the obtained esters was proven using instrumental methods of analysis. The antimicrobial and antifungal activity of the synthesized compounds was studied in vitro by the method of two-fold serial dilutions in liquid and solid nutrient environments. Antimicrobial activity screening showed that the synthesized esters have a moderate activity against gram-negative microorganisms and C. albicans. It was found that the 4-methyl-2-chlorophenyl ester of coumarin-3-carboxylic acid had the greatest bacteriostatic activity against Ps. aeruginosa and Pr. vulgaris, 2-chlorophenyl ester of coumarin-3-carboxylic acid against Ps. aeruginosa and E. coli, coumarin-3-carboxylic acid 4-hydroxyphenyl ester against Pr. vulgaris, and coumarin-3-carboxylic acid 2-isopropyl-5-methylphenyl ester against E. coli at a concentration of 31.25 g/ml. 2-Chlorophenyl ester also showed a bactericidal effect against E. coli. The synthesized compounds also have an antifungal effect against the C. albicans. strain used in the experiment. Thus, 4-methyl-2-chlorophenyl ester, 4-fluorophenyl ester, 4-hydroxyphenyl ester, 2,3-dihydroxyphenyl ester, 2-isopropyl-5-methylphenyl ester of coumarin-3-carboxylic acid are active at a concentration of 31.25 g/ml.

Detection of volatile hydroperfluoroalkanes during hydrothermal liquefaction of perfluoroalkyl carboxylic acids at circumneutral pH

Hydrothermal liquefaction (HTL) is a promising technology for converting wet organic waste such as sewage sludge into biocrude oil while simultaneously destroying per- and polyfluoroalkyl substances (PFAS). This study tracked the fate and degradation of six representative PFAS in water to address the effect of perfluoroalkyl chain length on degradation rates and the formation of volatile transformation products at 300–350 °C. While perfluorosulfonic acids were recalcitrant, perfluoroalkyl carboxylic acids (PFCAs) were rapidly and completely decarboxylated to hydroperfluoroalkanes (1 H-perfluoroheptane in the case of perfluorooctanoic acid). The volatile hydroperfluoroalkane was subsequently defluorinated without detectable fluorocarbon intermediates yielding 30–60 % defluorination for ammonium perfluoro(2-methyl-3-oxahexanoate), perfluorobutanoic acid and perfluorooctanoic acid after 2 h at 350 °C. Increasing temperature (especially at 350 °C) and longer perfluoroalkyl chains substantially enhanced the defluorination. This is the first study to report volatile hydroperfluoroalkanes from PFCAs in HTL, raising concern about the potential emission of long-lived greenhouse gasses into the atmosphere, but also opening new avenues for PFAS destruction through HTL.

Reflood oxidation performances of Cr-coated Zr-Sn-Nb alloy cladding tubes at 1000 °C∼1200 °C

Reflood plays an important role in preventing the serious accident process. In this paper, the reflood oxidation performances of Cr-coated Zr-Sn-Nb alloy cladding tubes at 1000 °C, 1100 °C and 1200 °C were studied by high-temperature steam oxidation followed by in-situ water quenching. The oxidation kinetics, macroscopic morphology, phase transformation and microstructural evolution were investigated. Cr coating can provide excellent anti-reflood oxidation protection for Zr-Sn-Nb alloy, resulting in an oxidation rate constant of only 1/4–1/7 of that of uncoated Zr-Sn-Nb alloys. However, the cladding tube degraded into fragments due to excessive thermal stress during the in-situ water quenching after reflood oxidation at 1200 °C for 4000 s. After reflood oxidation at 1000 °C and 1100 °C, the most prominent feature of the surface is a porous flocculation structure main due to the formation of volatile products, while after 1200 °C, it is a fine mackerel scale-like structure accompanied by protruding whiskers main owing to Cr3+ rapidly migrates outward to the outer surface via short circuit paths. After oxidation, the cross-section of Cr-coated Zr-Sn-Nb alloys exhibits a multi-layer structure. The thickness of each layer changes approximately linearly with oxidation time. However, due to the redox reaction, compared to that after oxidation for 2000s, the Cr2O3 layer becomes thinner and the residual Cr coating becomes thicker after oxidation at 1200 °C for 4000 s.

Formation of lipid-derived volatile products through lipoxygenase (LOX)- and hydroperoxide lyase (HPL)- mediated pathway in oat, barley and soy bean

The aim of this study was to explore the formation of volatile lipid oxidation products by the lipoxygenase (LOX)-hydroperoxide lyase (HPL)-mediated pathway in oat, barley and soy bean. LOX activity was found only in barley and soy bean samples, but the lipase and HPL activity was detected in all samples. HPL showed particularly high activity with 13-hydroperoxides, while the activity was quite low when using 9-hydroperoxides, especially in the oat and barley. The optimum pH for HPL in different samples was similar, i.e., pH 6–7. In this condition, the volatile compounds formed dramatically with aldehydes and furans as the dominant products. Furthermore, a remarkable enzymatic degradation of lipids occurred during the preparation of food models with highly refined rapeseed oil (RO) and rapeseed oil fatty acid (ROFA) emulsions, where the ROFAs were more prone to oxidation than RO. This study shows the significance of lipid-degrading enzymes in plant-food flavour formation.

Influence of Nano-CeO2 and Graphene Nanoplatelets on the Conductivity and Dielectric Properties of Poly(vinylidene fluoride) Nanocomposite Films.

Novel three-phase polymer nanocomposites (PNCs) based on cerium oxide (CeO2) nanoparticles (NPs) and graphene nanoplatelets (GNPs) incorporated in a poly(vinylidene fluoride) (PVDF) matrix were formulated using a solution-casting approach. To understand the structural and morphological features of PVDF/CeO2/GNP nanocomposites (NCs), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses were accomplished. The PVDF/CeO2/GNP NCs displayed improved thermal stability which resulted from strong bonding between GNPs and CeO2 NPs and restriction of the polymer chain movement. The introduction of CeO2 NPs and GNPs within the PVDF matrix and good synergy between CeO2 NPs and GNPs led to variable mechanical properties of the prepared NCs. The PVDF/CeO2/GNP NCs portrayed reduced thermal stability, which could be due to the increased mobility of PVDF chains imposed by GNPs leading to the formation of volatile degradation products. Moreover, PVDF/CeO2/GNP NCs exhibited good electrical conductivity and high dielectric permittivity. The obtained dielectric permittivity value for the PVDF/CeO2/GNP NCs was 3-fold greater than PVDF/CeO2 NCs, making these novel tertiary composite materials a probable candidate for energy-storage applications.

Composition dependence of X-ray stability and degradation mechanisms at lead halide perovskite single crystal surfaces.

The multiple applications of lead halide perovskite materials and the extensive use of X-ray based techniques to characterize them highlight a need to understand their stability under X-ray irradiation. Here, we present a study where the X-ray stability of five different lead halide perovskite compositions (MAPbI3, MAPbCl3, MAPbBr3, FAPbBr3, CsPbBr3) was investigated using photoelectron spectroscopy. To exclude effects of thin film formation on the observed degradation behaviors, we studied clean surfaces of single crystals. Different X-ray resistance and degradation mechanisms were observed depending on the crystal composition. Overall, perovskites based on the MA+ cation were found to be less stable than those based on FA+ or Cs+. Metallic lead formed most easily in the chloride perovskite, followed by bromide, and only very little metallic lead formation was observed for MAPbI3. MAPbI3 showed one main degradation process, which was the radiolysis of MAI. Multiple simultaneous degradation processes were identified for the bromide compositions. These processes include ion migration towards the perovskite surface and the formation of volatile and solid products in addition to metallic lead. Lastly, CsBr formed as a solid degradation product on the surface of CsPbBr3.

UV aging of styrene-acrylic polymer SiO2 and TiO2 composites

The photodegradation of coatings based on styrene-acrylic polymer and nanoparticles: hydrophobized silica (40–70 nm) and photoactive titanium dioxide (50–100 nm) was investigated. By the means of FTIR, goniometry, and SEM, it is shown that the use of titanium dioxide provides acceleration of photooxidation processes in comparison with the silica-based system. However, the formation of volatile decomposition products is not accelerated, which leads to the formation of a textured surface with polar polymer residues. Such surfaces have high wettability because of the capillary structure and intrinsic high surface energy. It was confirmed that the addition of nanoparticles reduces the ablation rate to 0.74 µm/h for TiO2 and to 0.85 µm/h for SiO2 due to the UV shielding effect.

Mechanisms of the Formation of Nonvolatile and Volatile Oxidation Products from Methyl Linoleic Acid at High Temperatures.

The impact of the oxidation of linoleic acid cannot be overlooked in daily food consumption. This study used gas chromatography-mass spectrometry (GC-MS) to identify both nonvolatile oxidation products and volatile oxidation products of methyl linoleic acid at 180 °C and density function theory to investigate oxidation mechanisms. An analysis of nonvolatile oxidation products revealed the presence of three primary oxidation products. The three primary oxidation products were identified as hydroperoxides, peroxide-linked dimers, and heterocyclic compounds in a ratio of 2.70:1:3.69 (mmol/mmol/mmol). The volatile components of secondary oxidation products were found including aldehydes (40.77%), alkanes (19.89%), alcohols (9.02%), furans (6.11%), epoxides (0.46%), and acids (2.50%). DFT calculation proved that the secondary oxidation products mainly came from peroxides (77%). Finally, we look forward to our research contributing positively to lipid autoxidation and human health.

The Use of Soy and Egg Phosphatidylcholines Modified with Caffeic Acid Enhances the Oxidative Stability of High-Fat (70%) Fish Oil-in-Water Emulsions

This study investigated the effect of the combined use of sodium caseinate (CAS), commercial phosphatidylcholine (PC), and modified PCs on the physical and oxidative stability of 70% fish oil-in-water emulsions. Caffeic acid was covalently attached to both modified PCs (PCs originated from soy and eggs) in order to increase the antioxidant activity of PCs and investigate the advantage of bringing the antioxidant activity to the close proximity of the oil-water interface. Results showed that oxidative stability was improved when part of the PC was substituted with modified soy PC or egg PC. Emulsions containing a low concentration of modified PCs (10 wt.% of total PC) resulted in a prooxidative effect on the formation of hydroperoxides compared to emulsions with free caffeic acid. On the other hand, a decrease in the formation of volatile oxidation products was observed for emulsions containing higher levels of modified PCs (60 wt.% of total PC) compared to the emulsions with free caffeic acid added at its equivalent concentration. Increased concentrations of modified PCs provided better oxidative stability in high-fat emulsions, independent of the modified PC type. Moreover, when oxidation was initiated by producing singlet oxygen near a single oil droplet using a focused laser, fluorescence imaging showed that the oxidation did not propagate from one oil droplet to another oil droplet.

Antioxidants location affects the oxidative stability of spray-dried microcapsules loaded with fish oil

The oxidative stability of fish oil-loaded capsules (∼15 wt% oil load) produced by spray-drying and containing natural antioxidants of different polarity was investigated. For this purpose, three commercial rosemary extracts (e.g., water-dispersible; K1 or oil-soluble; K2, K3) and whey protein concentrate hydrolysate (WPCH), exhibiting surface-active properties, were evaluated. The capsules showed similar physicochemical properties (e.g., morphology, size and encapsulation efficiency >91%), regardless of the formulation. However, the polarity of the antioxidant used significantly influenced the oxidative stability. The microcapsules containing hydrophobic antioxidants showed the lowest peroxide value (PV) after drying, followed by the WPCH-containing capsules, although the PV evolution over storage was similar among the samples. Nonetheless, WPCH was the most effective antioxidant reducing the formation of volatile secondary oxidation products in the capsules. This was attributed to its partition at the oil/matrix interface, resulting in an enhanced protective effect when combined with tocopherols present in the encapsulated oil.

Molecular dynamics approach for the calculation of the surface loss probabilities of neutral species in argon–methane plasma

AbstractMolecular dynamics simulations are carried out for calculating the surface loss probabilities of neutral species from an argon–methane plasma. These probabilities are the sum of the sticking and surface recombination probabilities. This study considers both the formation of reactive and nonreactive volatile species for evaluating recombination probabilities. Results show that stable species are reflected when hydrocarbon film starts growing on the surface. CH3 is mainly lost by surface recombination leading to the formation of volatile products while very little contributes to film growth. C2H has surface loss probability in agreement with the literature. While C2H loss is usually attributed to sticking on the surface, our results show that its main loss process is due to surface recombination.

Влияние фосфорсодержащих антипиренов на показатели пожарной опасности газонаполненных полимеров на основе реакционноспособных олигомеров

Introduc tion. The reduction of flammability of gas-filled polymers prone to carbonization is based on the use of phosphorus- and boron-containing compounds that reduce the formation of combustible volatile pyrolysis products and increase the yield of coke residue. This reduces the rate of heat release, heat and mass transfer between the material and the flame. In the scientific literature the data about the influence of phosphorus-containing flame retardants on thermal stability, combustibility and smokeability of foams are given, but there are no data about the influence of phosphorus concentration on fire danger indicators of foams. The aim of this paper is the development of effective methods of production of casting foams based on reactive oligomers with low fire hazard and high-performance. Objectives: to reveal the influence of phosphorus concentration on the technological and physical-mechanical characteristics, thermal resistance and fire hazard indices of foams and to develop fire-proof thermal insulation materials possessing high performance. Methods. Physical-mechanical properties and fire hazard indices of gas-filled polymers were determined according to current GOST. Thermal properties and composition of combustion products of foams have been studied with thermoanalytical complex DuPONT-9900 and chromatography-mass spectrometry. Results and discussion. The concentration of phosphorus in the synthesis of rigid polyurethane foams with reduced flammability and high performance should exceed 2.1 % wt. The low-combustible urea foams have been obtained at a phosphorus concentration of 0.2–0.3 % wt. For the production of non-flammable, low-­flammable resin foams, the phosphorus concentration is 0.6–0.7 % wt. At the same time, organophosphorus flame retardants containing reactive groups are highly effective. Conclusion s. As a result of experimental studies the influence of phosphorus concentration and content of organophosphorus-containing flame retardants on physical-mechanical properties, thermal stability and fire hazard of foams based on reactive oligomers was revealed, the pouring foams with lowered fire hazard and high performance were developed.

In Situ Spectroscopic Probing of Oxygen Crossover Effects on Solid Electrolyte Interphase in Aprotic Lithium‐Oxygen Batteries

AbstractThe solid electrolyte interphase (SEI) on lithium metal anodes (LMA) plays a critical role in affording a long lifespan required for aprotic lithium‐oxygen (Li–O2) batteries. Nevertheless, the crossover of oxygen from the cathode to the anode, an inevitable phenomenon for most of the current Li–O2 batteries, and its effects on the formation and operation of SEI on LMA remain less explored. In this work, a mechanistic study of the SEI formation at a model Cu/dimethyl sulfoxide (DMSO) interface in the presence of oxygen is presented. Direct spectroscopic evidence coupled with theoretical calculation reveals that oxygen can alter the SEI formation pathway and result in distinct SEI properties. Specifically, oxygen can inhibit the fission of the C–S bond of DMSO solvent and therefore reduce the formation of unstable SEI components (e.g., C≡C species) and volatile products (e.g., C2H6 and H2). Thus, the SEI formed under oxygen is more uniform and of less voids, and enables improved electrochemical performance of LMA. This work presents new insights into the oxygen crossover effects on SEI chemistry and is beneficial for designing better LMA/electrolyte interface for future Li–O2 batteries.

Understanding photochemical pathways of laser-induced metal ion reduction through byproduct analysis.

Laser-induced reduction of metal ions is attracting increasing attention as a sustainable route to ligand-free metal nanoparticles. In this work, we investigate the photochemical reactions involved in reduction of Ag+ and [AuCl4]- upon interaction with lasers with nanosecond and femtosecond pulse duration, using strong-field ionization mass spectrometry and spectroscopic assays to identify stable molecular byproducts. Whereas Ag+ in aqueous isopropyl alcohol (IPA) is reduced through plasma-mediated mechanisms upon femtosecond laser excitation, low-fluence nanosecond laser excitation induces electron transfer from IPA to Ag+. Both nanosecond and femtosecond laser excitation of aqueous [AuCl4]- produce reactive chlorine species by Au-Cl bond homolysis. Formation of numerous volatile products by IPA decomposition during both femtosecond and nanosecond laser excitation of [AuCl4]- is attributed to enhanced optical breakdown by the Au nanoparticle products of [AuCl4]- reduction. These mechanistic insights can inform the design of laser synthesis procedures to improve control over metal nanoparticle properties and enhance byproduct yields.

Plasma enhanced atomic layer deposition and atomic layer etching of gallium oxide using trimethylgallium

Atomic layer etching driven by self-limiting thermal reactions has recently been developed as a highly conformal and isotropic technique for low damage atomic scale material removal by sequential exposures of vapor phase reactants. Gallium oxide (Ga2O3) is currently among the materials of interest due to a large variety of applications including power electronics, solar cells, gas sensors, and photon detectors. In this study, Ga2O3 was deposited by plasma enhanced atomic layer deposition using trimethylgallium [TMG, Ga(CH3)3] and O2 plasma at a substrate temperature of 200 °C. We report a newly developed method for Ga2O3 thermal atomic layer etching, in which surface modification is achieved through HF exposure resulting in a gallium fluoride surface layer, and then removed through volatile product formation via ligand exchange with TMG. Saturation of the precursor exposure at a substrate temperature of 300 °C resulted in an etch rate of 1.0 ± 0.1 Å/cycle for amorphous Ga2O3. Uniformity and conformality of the atomic layer etching process were confirmed via atomic force microscopy with a measured surface roughness of 0.55 ± 0.05 nm that remains unchanged after etching. The use of TMG for etching may expand available precursors for atomic layer etching processes, while allowing for both etching and deposition of Ga2O3 using the same metalorganic precursor.

Multiphase Ozonolysis of Oleic Acid-Based Lipids: Quantitation of Major Products and Kinetic Multilayer Modeling.

Commonly found in atmospheric aerosols, cooking oils, and human sebum, unsaturated lipids rapidly decay upon exposure to ozone, following the Criegee mechanism. Here, the gas-surface ozonolysis of three oleic acid-based compounds was studied in a reactor and indoors. Under dry conditions, quantitative product analyses by 1H NMR indicate up to 79% molar yield of stable secondary ozonides (SOZs) in oxidized triolein and methyl oleate coatings. Elevated relative humidity (RH) significantly suppresses the SOZ yields, enhancing the formation of condensed-phase aldehydes and volatile C9 products. Along with kinetic parameters informed by molecular dynamics simulations, these results were used as constraints in a kinetic multilayer model (KM-GAP) simulating triolein ozonolysis. Covering a wide range of coating thicknesses and ozone levels, the model predicts a much faster decay near the gas-lipid interface compared to the bulk. Although the dependence of RH on SOZ yields is well predicted, the model overestimates the production of H2O2 and aldehydes. With negligible dependence on RH, the product composition for oxidized oleic acid is substantially affected by a competitive reaction between Criegee intermediates (CIs) and carboxylic acids. The resulting α-acyloxyalkyl hydroperoxides (α-AAHPs) have much higher molar yields (29-38%) than SOZs (12-16%). Overall, the ozone-lipid chemistry could affect the indoor environment through "crust" accumulation on surfaces and volatile organic compound (VOC) emission. In the atmosphere, the peroxide formation and changes in particle hygroscopicity may have effects on climate. The related health impacts are also discussed.

ДОСЛІДЖЕННЯ МЕХАНІЗМУ ВОГНЕЗАХИСТУ ТКАНИНИ ІНТУМЕСЦЕНТНИМ ПОКРИТТЯМ

Describing the behavior of fire retardants and coatings, including swelling, at the time of formation of the insulating structure is a separate and complex task. In general, it covers both stages of the heat protection process: as a rule, the decomposition of flame retardants under the action of temperature with heat absorption and the release of non-combustible gases, and then - swelling of the coating formed by fire protection. Therefore, it is necessary to study the conditions for the formation of a barrier to thermal conductivity and the establishment of a fire protection mechanism from layer to layer of coke. In this regard, a study of the process of fire protection during the operation of the fire protection coating. According to the data obtained, it is found that the formation of volatile products under the action of high temperature on the coating takes place with the formation of non-combustible substances. It has been experimentally established that under the action of heat flow on fire-retardant samples there is an intensive release of inert gases and a reduction of combustibles in reverse order. This proves the effectiveness of fire protection. During the tests it was found that the intensity of the formation of the swollen layer of coke moves in the direction of elevated temperature. The results of determining the swelling capacity of the coating for the intumescent system showed that under the action of high-temperature flow the burnout of the material and the loss of coating weight are reduced more than twice due to the formation of high-temperature compounds. The coating under the action of high temperature forms a significant coefficient of swelling, promotes the formation of a heat-insulating layer of coke, preventing burnout of the fabric and the passage of high temperature to the material, which is confirmed by reduced heat of combustion. It was determined that the fire-retardant fabric has almost 1.3 times less heat of combustion and is characterized by thermal decomposition by reducing flammable gases by more than 50% and increasing inert gases by more than 8 times.

Effects of herbivory on carotenoid biosynthesis and breakdown.

The carotenoid content of plants may be impacted by stress with major consequences for photosynthesis and photoprotection. Most carotenoid stress research, however, has concentrated on abiotic stresses, and we know little about how biological stresses, such as herbivory, alter profiles of plant carotenoids and their degradation products. For example, carotenoid derivatives such as β-cyclocitral and β-ionone have been recently shown to act as signals in plant growth and protection against oxidative stress and herbivory. To understand how carotenoid composition is influenced by herbivory, changes in biosynthesis and degradation should be investigated. This chapter describes methods to simulate herbivory in a simple reproducible fashion and to assess carotenoid biosynthesis and degradation. Carotenoid biosynthesis depends on precursors provided by the methylerythritol 4-phosphate (MEP) pathway, which converts pyruvate and glyceraldehyde-3-phosphate to the five-carbon units used for construction of larger isoprenoids. We present protocols to quantify the activity of the first enzyme of the MEP pathway, deoxy-xylulose 5-phosphate synthase (DXS), usually assumed to be rate-controlling, and to estimate the concentration of the first intermediate of the pathway, deoxy-xylulose 5-phosphate (DXP). We also discuss procedures to measure the formation of volatile carotenoid breakdown products after herbivory. To monitor the activity of carotenoid-specific biosynthetic enzymes, such as phytoene synthase, protocols are available elsewhere in this volume (Wurtzel, 2022b).

Physical and Oxidative Stability of Low-Fat Fish Oil-in-Water Emulsions Stabilized with Black Soldier Fly (Hermetia illucens) Larvae Protein Concentrate.

The physical and oxidative stability of fish oil-in-water (O/W) emulsions were investigated using black soldier fly larvae (BSFL) (Hermetia illucens) protein concentrate as an emulsifier. To improve the protein extraction and the techno-functionality, defatted BSFL powder was treated with ohmic heating (BSFL-OH) and a combination of ohmic heating and ultrasound (BSFL-UOH). Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were performed in order to characterize the secondary structure and thermal stability of all protein concentrate samples. The interfacial properties were evaluated by the pendant drop technique. The lowest interfacial tension (12.95 mN/m) after 30 min was observed for BSFL-OH. Dynamic light scattering, ζ-potential and turbiscan stability index (TSI) were used to evaluate the physical stability of emulsions. BSFL-OH showed the smallest droplet size (0.68 μm) and the best emulsion stability (TSI = 8.89). The formation of primary and secondary volatile oxidation products and consumption of tocopherols were evaluated for all emulsions, revealing that OH and ultrasound treatment did not improve oxidative stability compared to the emulsion with untreated BSFL. The results revealed the promising application of BSFL proteins as emulsifiers and the ability of ohmic heating to improve the emulsifying properties of BSFL proteins.