Study on Key Aroma Compounds and Its Precursors of Peanut Oil Prepared with Normal- and High-Oleic Peanuts

High-oleic acid peanut oil has developed rapidly in China in recent years due to its high oxidative stability and nutritional properties. However, consumer feedback showed that the aroma of high-oleic peanut oil was not as good as the oil obtained from normal-oleic peanut variety. The aim of this study was to investigate the key volatile compounds and precursors of peanut oil prepared with normal- and high-oleic peanuts. The peanut raw materials and oil processing samples used in the present study were collected from a company in China. Sensory evaluation results indicated that normal-oleic peanut oil showed stronger characteristic flavor than high-oleic peanut oil. The compounds methylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine and benzaldehyde were considered as key volatiles which contribute to dark roast, roast peanutty and sweet aroma of peanut oil. The initial concentration of volatile precursors (arginine, tyrosine, lysine and glucose) in normal-oleic peanut was higher than in high-oleic peanut, which led to more characteristic volatiles forming during process and provided a stronger oil aroma of. The present research will provide data support for raw material screening and sensory quality improvement during high-oleic acid peanut oil industrial production.

Exploring the composition and volatility of secondary organic aerosols in mixed anthropogenic and biogenic precursor systems

Secondary organic aerosol (SOA) formation from mixtures of volatile precursors may be influenced by the molecular interactions of the components of the mixture. Here, we report measurements of the volatility distribution of SOA formed from the photo-oxidation of o-cresol, α-pinene, and their mixtures, representative anthropogenic and biogenic precursors, in an atmospheric simulation chamber. The combination of two independent thermal techniques (thermal denuder, TD, and the Filter Inlet for Gases and Aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer, FIGAERO-CIMS) to measure the particle volatility, along with detailed gas- and particle-phase composition measurements, provides links between the chemical composition of the mixture and the resultant SOA particle volatility. The SOA particle volatility obtained by the two independent techniques showed substantial discrepancies. The particle volatility obtained by the TD was wider, spanning across the LVOC and SVOC range, while the respective FIGAERO-CIMS derived using two different methods (i.e. calibrated Tmax and partitioning calculations) was substantially higher (mainly in the SVOC and IVOC, respectively) and narrow. Although the quantification of the SOA particle volatility was challenging, both techniques and methods showed similar trends, with the volatility of the SOA formed from the photo-oxidation of α-pinene being higher than that measured in the o-cresol system, while the volatility of the SOA particles of the mixture was between those measured at the single-precursor systems. This behaviour could be explained by two opposite effects, the scavenging of the larger molecules with lower volatility produced in the single-precursor experiments that led to an increase in the average volatility and the formation of unique-to-the-mixture products that had higher O:C, MW, OSc‾ and, consequently, lower volatility compared to those derived from the individual precursors. We further discuss the potential limitations of FIGAERO-CIMS to report quantitative volatilities and their implications for the reported results, and we show that the particle volatility changes can be qualitatively assessed, while caution should be taken when linking the chemical composition to the particle volatility. These results present the first detailed observations of SOA particle volatility and composition in mixed anthropogenic and biogenic systems and provide an analytical context that can be used to explore particle volatility in chamber experiments.

TSF-MOCVD – a novel technique for chemical vapour deposition on oxide thin films and layered heterostructures

A new principle for supplying volatile precursors to MOCVD gas-phase chemical deposition systems is proposed, based on a two-stage evaporation of an organic solution of precursors from a soaked cotton thread, which passes sequentially through the zones of evaporation of the solvent and precursors. The technological capabilities of TSF-MOCVD (Thread-Solution Feed MOCVD) are demonstrated based on examples of obtaining thin epitaxial films of СеО2, h-LuFeO3 and thin-film heterostructures β-Fe2O3/h-LuFeO3. The results of studying the obtained films by X-ray diffraction, energy dispersive X-rayanalysis, and high- and low-resolution transmission microscopy are presented. Using the TSF module, one can finely vary the crystallisation conditions, obtaining coatings of the required degree of crystallinity, as evidenced by the obtained dependences of the integral width of the h-LuFeO3 reflection on the film growth rate. Based on the TEM and XRD data, it was concluded that β-Fe2O3 grows epitaxially over the h-LuFeO3 layer. Thus, using TSF-MOCVD, one can flexibly change the composition of layered heterostructures and obtain highly crystalline epitaxial films with a clear interface in a continuous deposition process

New Precursors to 3-Sulfanylhexan-1-ol? Investigating the Keto–Enol Tautomerism of 3-S-Glutathionylhexanal

The volatile thiol compound 3-sulfanylhexan-1-ol (3SH) is a key impact odorant of white wines such as Sauvignon Blanc. 3SH is produced during fermentation by metabolism of non-volatile precursors such as 3-S-gluthathionylhexanal (glut-3SH-al). The biogenesis of 3SH is not fully understood, and the role of glut-3SH-al in this pathway is yet to be elucidated. The aldehyde functional group of glut-3SH-al is known to make this compound more reactive than other precursors to 3SH, and we are reporting for the first time that glut-3SH-al can exist in both keto and enol forms in aqueous solutions. At wine typical pH (~3.5), glut-3SH-al exists predominantly as the enol form. The dominance of the enol form over the keto form has implications in terms of potential consumption/conversion of glut-3SH-al by previously unidentified pathways. Therefore, this work will aid in the further elucidation of the role of glut-3SH-al towards 3SH formation in wine, with significant implications for the study and analysis of analogous compounds.

Exploring the composition and volatility of secondary organic aerosols in mixed anthropogenic and biogenic precursor systems

Secondary organic aerosol (SOA) formation from mixtures of volatile precursors may be influenced by the molecular interactions of the products of the components of the mixture. Here, we report measurements of the volatility distribution of SOA formed from the photo-oxidation o-cresol, α-pinene and their mixtures, representative anthropogenic and biogenic precursors, in an atmospheric simulation chamber. The combination of two independent thermal techniques (thermal denuder and the Filter Inlet for Gases and Aerosols coupled to a high resolution time of flight chemical ionisation mass spectrometer) to measure the particle volatility, along with detailed gas and particle phase composition measurements provides links between the chemical composition of the mixture and the resultant SOA volatility. The products that were only present in the SOA of the mixture had higher O:C and lower volatility compared to those deriving from the individual precursors. This suggests that new product formation can reduce the volatility in mixtures. At the same time, some of the larger molecules with lower volatility produced in the single α-pinene and o-cresol system were not present in the mixture leading to an increase of the average volatility. These opposite effects resulted the volatility distribution of the SOA of the mixture to be between those of the individual precursors. For example, compounds with effective saturation concentration less or equal than 0.01 μg m−3 represented 28, 39 and 37 % of the SOA mass in the α-pinene, o-cresol and mixed precursor experiments, respectively. We further explore the sensitivity limitations of our technique to the reported results and we show that the particle volatility can be qualitatively assessed, while caution should be held when linking the chemical composition to the particle volatility. These results provide the first detailed observations of SOA particle volatility and composition in mixed anthropogenic and biogenic systems and provides an analytical context that can be used to explore particle volatility in chamber experiments.

β-Glucosidase Activity of Lactiplantibacillus plantarum UNQLp 11 in Different Malolactic Fermentations Conditions: Effect of pH and Ethanol Content

Lactiplantibacillus plantarum strain UNQLp 11 is a lactic acid bacterium with the potential to carry out malolactic fermentation (MLF) in red wines. Recently, the complete genome of UNQLp 11 was sequenced and this strain possesses four loci of the enzyme β-glucosidase. In order to demonstrate that these glucosidase enzymes could be functional under harsh wine conditions, we evaluated the hydrolysis of p-nitrophenyl-β-D-glucopyranoside (p-NPG) in synthetic wine with different ethanol contents (0%, 12%, and 14% v/v) and at different pH values (3.2, 3.5, and 3.8). Then, the hydrolysis of precursor n-octyl β-D-glucopyranoside was analyzed in sterile Pinot Noir wine (containing 14.5% v/v of ethanol, at different pH values) by headspace sorptive extraction gas chromatography-mass spectrometry (HSSE-GC/MS). The hydrolysis of p-NPG showed that β-glucosidase activity is very susceptible to low pH but induced in the presence of high ethanol content. Furthermore, UNQLp 11 was able to release the glycosilated precursor n-octyl, during MLF to a greater extent than a commercial enzyme. In conclusion, UNQLp 11 could improve the aromatic profile of the wine by the release of volatile precursors during MLF.

Towards Volatile Organoselenium Compounds with Cost-Effective Synthesis

The current portfolio of organoselenium compounds applicable as volatile precursors for atomic layer deposition can be denoted as very limited. Hence, we report herein facile and cost-effective preparation of two bis(trialkylstannyl)selenides as well as one selenole and three bis(trialkylsilyl)selenides. Their syntheses have been optimized to: (i) use readily available and inexpensive starting materials, (ii) involve operationally simple methodology (heating in a pressure vessel), (iii) use a minimum amount of additives and catalysts, and (iv) either exclude additional purification or involve only simple distillation. The chemical structure of prepared Se derivatives was confirmed by multinuclear NMR and GC/MS. Their fundamental thermal properties were investigated by differential scanning calorimetry (DSC) and TGA methods that revealed thermal stability within the range of 160–300 °C.

Recent Advancements in the Use of Aerosol-Assisted Atmospheric Pressure Plasma Deposition

Atmospheric pressure plasma allows for the easy modification of materials’ surfaces for a wide range of technological applications. Coupling the aerosol injection of precursors with atmospheric pressure plasma largely extends the versatility of this kind of process; in fact solid and, in general, scarcely volatile precursors can be delivered to the plasma, extending the variety of chemical pathways to surface modification. This review provides an overview of the state of the art of aerosol-assisted atmospheric pressure plasma deposition. Advantages (many), and drawbacks (few) will be illustrated, as well as hints as to the correct coupling of the atomization source with the plasma to obtain specific coatings. In particular, the deposition of different organic, hybrid inorganic–organic and bioactive nanocomposite coatings will be discussed. Finally, it will be shown that, in particular cases, unique core–shell nanocapsules can be obtained.

MIXED-LIGAND ACETYLACETONATE COMPLEXES OF LANTANUM (III) AND GADOLINIUM (III) WITH CARBOXYLIC ACIDS AND ACETONITRILE OR DIMETHYLFORMAMIDE

This paper presents the study of mixed-ligand complexes of Ln(III), which are used as volatile precursors in CVD processes for the preparation of lanthanide-containing films and coatings. New mixed-ligand acetylacetonate complexes of lanthanides (III) with acetic (propionic) acid and acetonitrile or dimethylformamide were synthesized and investigated by physic-chemical methods of analysis (elemental analysis, differential thermal analysis, IR spectroscopy, powder X-ray diffraction). Using mixed-ligand complexation, the properties of the initial lanthanide β-diketonates (in particular, chemical and thermal stability) can be changed significantly. To assess the stability of the synthesized mixed-ligand complexes, their quantum-chemical modeling was performed using the semi-empirical method Sparkle/PM7. Standard changes of the Gibbs energy ∆G0298 were calculated for the solution reaction of (1) synthesis of mixed-ligand complexes and (2) substitution of one of the β-diketonate ligands in the Ln(III) tris-acetylacetonates dihydrates by an acetate ion or propionate ion. The ∆G0298 values for the syntesis reaction mainly increases with increasing donor basicity and decreasing ionic radii Ln(III) in the La>Gd>Lu series. For all mixed ligand complexes of Ln(III), the heats of formation are negative, which indicates their thermodynamic stability in solution. It was established that the obtained complexes have the same composition of the general formula [Ln(AA)2·L·2D], where Ln (III) = La, Gd; НАА- acetylacetonе; L - anion of acetic (HAc) or propionic (HРrop) acids, D- acetonitrile (AN), dimethylformamide (DMFA). The results of the thermal analysis confirm the computational data: in the case of the lanthanum mixed-ligand complexes, the carboxylic acid is coordinated to the central ion through bridging carboxylate-ions, which contributes to the formation of oligomers. The lanthanum mixed-ligand complexes are not volatile due to their oligomeric structure. On the other hand, similar gadolinium complexes are monomeric and sublimate at 180 - 350 °C.