Kinds Of Aldehydes Research Articles

Analysis of Pickled Cucumber Products, Based on Microbial Diversity and Flavor Substance Detection.

Changes to the microbial community during pickled cucumber fermentation were studied using the 16S rDNA technique. The changes of volatile organic compounds (VOCs) during pickled cucumber fermentation were studied by gas chromatograph-ion mobility spectrometry. At the phylum level, Cyanophyta and Proteobacteria were the dominant flora in the natural fermentation group, and Firmicutes were the dominant flora in the added-bacteria fermentation group. At the generic level, the addition of Lactobacillus led to changes in the community of the bacteria in the added-bacterial fermentation group and decreased the species abundance of other bacteria. In total, 75 volatile organic compounds were identified from naturally fermented pickled cucumber, and 60 volatile organic compounds were identified from fermented pickled cucumber with bacterial addition. The main metabolites were esters, aldehydes, acids, alcohols, ketones, alkanes, nitriles, and alkenes. These metabolites will bring their unique aroma components to the pickled cucumber. Metabolomic analysis of the O2PLS model showed that Weissella and Lactobacillus were closely and positively correlated with nine alcohols, six esters, five aldehydes, four acids, three ketones, and one pyrazine. Pseudomonas and norank_f_Mitochondria show a close positive correlation with four kinds of alcohols, two kinds of esters, one kind of aldehyde, and one kind of nitrile.

The Relationship between Microbial Community Succession and Flavor Formation during the Natural Fermentation of Hongqu sufu.

To study the diversity of microbial flora in Hongqu sufu and analyze the characteristics of special flavor compounds, this study took self-made Hongqu sufu as the research object. Dynamic changes in sufu during fermentation were studied. High-throughput sequencing (HTS) was used to analyze changes in the diversity of fungal and bacterial communities during fermentation. The results showed that at the phylum level, the dominant fungal phyla were identified, Mucormyces and Ascomycetes. The dominant bacterial phyla were Proteobacteria and Firmicutes. At the genus level, the dominant fungal genera were identified as Actinomucor, Monascus, and Aspergillus. The dominant bacterial genera were Pseudomonas, Aneurimibacillus, Sphingobacterium, and Bacillus. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with technology that can dynamically change flavor compounds was explored to investigate the correlation between microbiota and flavor compounds. In different stages of fermentation, 75 main volatile organic compounds were identified, including seven alcohols, four acids, 16 alkanes, 14 olefins, seven kinds of aldehydes, two kinds of ketones, 10 kinds of esters, one kind of phenol, one kind of sulfur-containing compound, one benzene, and 12 other compounds. The correlation analysis between flora and flavor compounds showed that the fungi genera Alternaria and Pichia were significantly correlated with most flavor compounds. Bacteria genera including Weissella, Hafnia-Obesumbacterium, and Leuconostoc had a strong positive correlation with ethyl oleate.

Houttuynia cordata Thunb. crude extract inactivates Cronobacter sakazakii: Antibacterial components, antibacterial mechanism, and application as a natural disinfectant

The purpose of this study was to reveal the antibacterial components of Houttuynia cordata Thunb. crude extract (HCCE), analyze the antibacterial activity and mechanism of HCCE against Cronobacter sakazakii, and evaluate the bactericidal effect of HCCE as a natural disinfectant. Using an ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-QE-MS) non-target metabolomics technology, 15 kinds oforganic acids (18.65%), 14 kinds of phenols (16.17%), 10 kinds of flavonoids (12.32%), 5 kinds of terpenoids (5.87%), 3 kinds of alkaloids (1.62%), and 3 kinds of aldehydes (1.28%) were detected from HCCE. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of HCCE against C. sakazakii were 7.5 mg/mL and 15 mg/mL, respectively, and when the concentration was 2 MIC, C. sakazakii stagnated in sluggish phase. C. sakazakii exposed to HCCE showed hyperpolarization of cell membrane, increased intracellular ROS content, decreased protein and DNA content, impaired cell membrane integrity, improved cell membrane permeability, cell fluid leakage, and partial cell fragmentation. After treatments with 1 MIC and 2 MIC of HCCE for 5 min, C. sakazakii strains on 8 contact surfaces including stainless steel, tinplate, glass, polystyrene, bamboo, plank, ceramic, and tin foil paper were significantly inhibited (P < 0.05), and the reduction amounts ranged from 3.00 to 3.68 log CFU/100 cm2 and 3.97 to 4.53 log CFU/100 cm2, respectively. These findings demonstrate the potential of HCCE as a natural disinfectant and provide a new idea to reduce the C. sakazakii contamination caused by surface contact.

Effects of acetic acid bacteria in starter culture on the properties of sourdough and steamed bread

Sourdough starters for making traditional steamed bread are rich in microbes. Studies have shown that, in addition to yeast and lactic acid bacteria (LAB), acetic acid bacteria (AAB) are other functional species in sourdough, but the influences of AAB on the properties of sourdough and steamed bread were rarely reported. This study aimed to assess the effects of a selected strain of acetic acid bacterium on the properties of sourdough and steamed bread. Sourdoughs and steamed breads were prepared from five different starter cultures, marked as CK (control check, with no starters), Y (only yeast), YL (yeast+LAB), YA (yeast+AAB) and YLA (yeast+LAB+AAB), and their properties were determined. The results of sourdough properties showed that the YLA sourdough had the highest total titratable acid of 14.6 mL and the lowest pH of 3.87 compared with the other groups after fermentation to 8 h; and the YLA sourdough had the greatest elasticity and viscosity. The results of quality properties of steamed bread revealed that the L* value (88.40 ± 0.09) of the YA steamed bread was significantly higher than those of the YLA and YL steamed breads; the YLA steamed bread had the highest specific volume and the highest sensory score of 89.6 ± 3.31 in comparison to those of the other groups; the hardness and chewiness of YLA and YA steamed breads were significantly lower than those of the other groups. Volatile compounds in the steamed breads were also determined by SPME–GC–MS. A total of 42 flavor substances were detected, including 3 kinds of alcohols, 8 kinds of aldehydes, 7 kinds of ketones, 2 kinds of acids, 15 kinds of esters, 1 furan, and 6 kinds of other types of compounds, mainly alkanes and esters, followed by alcohols and aldehydes. The YLA steamed bread was richer in esters, aldehydes, and acids than those from the other treatment groups. By contrast, alkanes and aldehydes were dominant in the Y and YL steamed breads. Therefore, the flavor and quality of the steamed bread made from the YLA sourdough could be improved obviously. These results could provide references for the application of AAB in dough fermentation and the improvement of new kinds of starters.

A recombinant L-threonine aldolase with high diastereoselectivity in the synthesis of L-threo-dihydroxyphenylserine

• A new L-threonine aldolase was expressed and mutated. • R318 L showed by far the best stereoselectivity in the synthesis of L- threo -DOPS. • The molecular mechanism for enhanced stereoselectivity was speculated. L-Threonine aldolase (L-TA) is a promising candidate for the optical synthesis of β-hydroxy-α-L-amino acids from glycine and kinds of aldehydes. Because of the C β -stereoselectivity problem, it was usually difficult to optically synthesize β-hydroxy-α-L-amino acids with C β -aromatic groups by application of L-TAs, especially those existing electron-donating groups on C β -aromatic groups, such as anti-Parkinson’s disease drug L- threo -DOPS (L- threo -3,4- dihydroxyphenylserine). A new L-TA (named Sz-1−2) from the gut microbiota of black bears was expressed and its Arg318 site-saturation mutation was conducted. Under the optimized conditions, three mutants R318 M, R318 V and R318 L showed 77.1 %, 79.9 % and 84.9 % de values respectively, which significantly improved than the wild-type (31.2 % de ). Importantly, the mutant R318 L provided by far the best diastereoselectivity in the synthesis of L- threo -DOPS, 1.5 folds higher than the best-ever enzyme (55.4 % de ). The L-TA R318 L is a valuable enzyme for the synthesis of L- threo -DOPS and might also be promising for the enzymatic synthesis of other important β-hydroxy-α-L-amino acids. Moreover, our research also suggested Arg318 was a crucial residue for the improvement of the diastereoselectivity of L-TAs, which could provide valuable experience for the relevant studies.

Magnetized inorganic–bioorganic nanohybrid [nano Fe3O4‐SiO2@Glu‐Cu (II)]: A novel nanostructure for the efficient solvent‐free synthesis of thiazolidin‐2‐imines

In this research, a solvent‐free four‐component one‐pot reaction of phenyl isothiocyanate, phenylacetylene, various kinds of aldehydes, and amines was interpreted to obtain the desired five‐membered heterocycles named thiazolidin‐2‐imines. The promotor of this transformation is a novel magnetite‐based multilayered inorganic–bioorganic nanohybrid prepared via embedding glutamic acid on the magnetized silica followed by anchoring Cu (II) [nano Fe3O4‐SiO2@Glu‐Cu (II)]. The newly synthesized nanostructure is characterized through Fourier‐transform infrared (FT‐IR), field‐emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDAX), transmission electron microscopy (TEM), X‐ray fluorescence (XRF), thermogravimetric analysis or derivative thermogravimetric (TGA/DTG), vibrating sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) techniques. This protocol is a straightforward one‐step procedure to obtain thiazolidin‐2‐imines without requirement to propargylamines or imines as substrates. In addition, easy work‐up procedure, high yields of products, absence of organic solvents in the reaction media, recovery and reusability of nano Fe3O4‐SiO2@Glu‐Cu (II) to promote the reaction at least for three runs without activity lost, simple separation of the catalyst from reaction mixture via an external magnet, and regioselectivity of the method are some highlighted aspects of the approach.

Fluorine Effects for Tunable C–C and C–S Bond Cleavage in Fluoro-Julia–Kocienski Intermediates

Classical Julia–Kocienski fluoroolefination represents an indispensable platform for the construction of monofluoroalkenes. Nevertheless, its complex multistep mechanistic manifold along with the u...

Analysis of Volatile Components in Gui Qi Mango Fruit Wine

The volatile components in Gui Qi Mango fruit wine analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry. Results showed that 32 kinds of volatile components were detected in Gui Qi Mango fruit wine, including 7 kinds of alcohols (65.69%), 17 kinds of esters (28.92%), 4 kinds of alkanes (2.16%), 3 kinds of aldehydes (0.36%), 2 kinds of olefins (0.32%), 1 kinds of ketones (0.41%), 1 kinds of phenols (0.2%). In the all of the volatile components, the relative content of alcohols and esters were 94.61%. The fermentation process had an effect on the Gui Qi Mango fruit wine, and alcohols and esters played a positive role in the aroma of Gui Qi Mango fruit wine.

Chemo- and Diastereoselective Synthesis of N-Propargyl Oxazolidines through a Copper-Catalyzed Domino A3 Reaction.

Herein we describe a highly chemoselective A3-coupling/annulation of amino alcohols, formaldehyde, two kinds of aldehydes and alkynes, catalyzed by copper(II). This cascade reaction, employing readily available materials, provides a new and highly effective access to chiral N-propargyl oxazolidines with good diastereoselectivity (up to >20:1). In the case of ortho-substituted aromatic aldehydes, an intriguing steric effect is observed: a bulky group exhibits a remarkably adverse effect on the diastereoselectivity for the formation of the title molecule.

Effect of straw incorporation on aldehyde emissions from a maize cropping system: A field experiment

Aldehyde may occupy an important role in the volatile organic compound (VOC) emissions from soil and plant residue. However, aldehyde emission from agricultural soil as well as the effect of straw incorporation is poorly understood. Therefore, a field straw incorporation experiment comprising two treatments, (1) S0 (no straw incorporation) and (2) S1 (incorporation of maize straw at a rate of 9000 kg ha−1), was performed in a maize cropping system to characterize the emissions of aldehyde as well as to estimate the effect of straw incorporation on aldehyde emissions. Nine kinds of aldehydes were investigated and three emission dynamic modes were observed during the experiment. Total aldehydes emissions were significantly different (426.8 and 540.2 g ha−1 for S0 and S1, respectively). Generally speaking, decanal and nonanal had an obvious predominance in both treatments, taking up 33.1% and 29.2% of the total aldehydes emission for S0, and 30.4% and 28.4% for S1, respectively. In addition, the practice of straw incorporation significantly increased the emissions of the 9 kinds of aldehydes by 11.2%–103.3%, and the total aldehydes emission from incorporated straw alone was calculated as 2918.8 ng kg straw−1 h−1. These results showed that straw incorporation substantially influenced the emissions of aldehydes from the agricultural soil. Additionally, a rough comparison indicated that straw incorporation might not have much advantage over straw open burning in terms of reducing VOC (i.e., aldehyde) emissions. The results also suggested that environmental conditions (i.e., soil temperature, moisture and pH), especially soil pH, played an important role in aldehyde fluxes from the agricultural soil.

Analysis of aroma compounds of pitaya fruit wine

In order to analyze the volatile components in red pitaya fruit wine, the study using headspace solid phase microextractionand gas chromatography-mass spectrometry technology of pitaya fruit juice and wine aroma composition analysis comparison. Results showed that 55 volatile components were detected in red pitaya fruit wine, including 12 kinds of alcohol (18.16%), 18 kinds of esters (66.17%), 7 kinds of acids (5.94%), 11 kinds of alkanes (4.32%), one kind of aldehyde (0.09%), 2 kinds of olefins (0.09%) and 3 kinds of other volatile substances (0.23%). Relative contents among them bigger have 11 species, such as decanoic acid, ethyl ester (22.92%), respectively, diisoamylene (20.75%), octanoic acid, ethyl ester (17.73%), etc. The red pitaya fruit wine contained a lot of aroma components, which offer the products special aroma like brandy, rose and fruit.

Selective Actinide-Catalyzed Tandem Proton-Transfer Esterification of Aldehydes with Alcohols for the Production of Asymmetric Esters

Actinide-catalyzed tandem proton-transfer esterification between aldehydes and alcohols is presented herein for the first time. It represents a novel convenient and external-oxidant-free methodology in the preparation of asymmetric ester compounds. Various kinds of aldehydes and alcohols can be applied to this reaction, affording the corresponding ester product in moderate to high yields. A plausible mechanism was proposed on the basis of the kinetic, stoichiometric, and deuterium-labeling studies.

Effect of aldehydes crosslinkers on properties of bacterial cellulose-poly(vinyl alcohol) (BC/PVA) nanocomposite hydrogels

The effects of the aldehydes crosslinkers on properties of the BC/PVA nanocomposite hydrogels were investigated. BC as the reinforcement and PVA as the matrix materials of the BC/PVA nanocomposite hydrogels, the hydrogels were prepared in coagulating bath of sodium sulfate and cross-linked with kinds of aldehydes. The hydrogels were characterized by Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), Equilibrium swelling ratio (ESR) tests, mechanical properties tests, thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) analysis. It was found that the dialdehyde (glyoxal, glutaraldehyde) crosslinkers were more efficient than monoaldehyde (formaldehyde, acetaldehyde) crosslinkers. The ESR, mechanical properties of the BC/PVA nanocomposite hydrogels were obviously influenced by aldehydes crosslinkers. However, their thermo stability and crystallinity were scarcely influenced. The nanocomposite hydrogels described in this study provides information for further development and optimization of a variety of nanofiber-polymer matrix composite hydrogels.

Synthesis and herbicidal activity of optically active α-(substituted phenoxyacetoxy) (substituted phenyl) methylphosphonates

α-(Substituted phenoxyacetoxy) alkylphosphonates containing one chiral carbon atom have been demonstrated to be PDHc inhibitor with good herbicidal activity and some of them could be used as potential herbicide. In order to determine any difference in herbicidal activities between (R) and (S) isomers, the synthetic method of optically active substituted phenylalkylphosphonates IB were explored. A highly practical, enantioselective hydrophosphonylation was developed to prepare optically active O,O-dimethyl α-hydroxyalkylphosphonates 3 as key intermediate by asymmetric addition reaction of dimethylphosphite 1 and several kinds of aldehydes 2 using tridentate Schiff base Al(III) complexes as catalysts. A series of novel O,O-dimethyl α-(substituted phenoxyacetoxy)(substituted phenyl)methylphosphonates IB including (R) and (S) enantiomers were further synthesized with excellent enantioselectivity (95–99% ee) by the condensation of optically active α-hydroxyl (substituted phenyl)methylphosphonates 3 and substituted phenoxyacetyl chlorides 4. The herbicidal activities of title compound IB including their racemates, (R) and (S) enantiomers were evaluated in greenhouse for post-emergence application. All compounds IB showed significant inhibitory activity against dicotyledonous plants. A difference in herbicidal effect among racemate, (R) and (S) enantiomers were observed. Especially IB7 and IB10 showed obvious chiral selectivity in inhibitory activity against chickweed. (S)-IB7 with ED50 of 22.8gai/ha was found to be most effective enantiomer against chickweed and its inhibitory activity was 8.17 times higher than (R)-IB7. (S)-IB7 as potential herbicide would be effective at lower rates than (R)-IB7 or (rac)-IB7.

Salmonella typhimurium 에 대한 E-ball 및 상용화된 소독약품의 살균 및 소독 효능에 대한 연구

Abstract Many chemical disinfectants are using to protect the foot and mouth disease (FMD) and avian influenza (AI) in Korea since 2000. This study was performed to confirm disinfective ability of commercialized chemical disinfectants and to investigate the sterilizing ability of E-ball as alterative to chemical disinfectants. 4 kinds of acidulant, 3 kinds of aldehyde, 1 kind of oxidizer and 300 g of E-ball were used in this study. Dilution rate of disinfective power of all chemical disinfectants were to 200 times. The sterilizing ability of aldehydes were better than the acidulant and oxidizer with Salmonella typhimurium . The sterilizing ability of E-ball treated solution was guessed due to the friction of E-ball deads. In the case of the friction of 2 beads of E-ball, Salmonella typhimurium was sterilizted on 1×10 6 /mL CFU in the E-ball treated solution. The E-ball treated solution had superior sterizing power compared with the chemical disinfectants in the bacteria of soil for antibacterial examination. E-ball treated solution has a possibility as the substitute of chemical disinfectants to protective the animal dis-eases contains FMD, AI.

Diverse states and properties of polymer nanoparticles and gel formed by polyethyleneimine and aldehydes and analytical applications.

Multicolor polymer nanoparticles (or dots) were prepared via the reaction between hyperbranched polyethyleneimine (PEI) and aldehydes, and when the concentration of aldehydes was lower, the final mixture displayed gelation behavior. This phenomenon can be applied to visual detection of aldehydes. Moreover, the colors of the polymer dots and gel are varied by using different kinds of aldehydes, which can be utilized for visual discrimination of aldehydes. For simplicity, we focus our attention on the interaction between PEI and formaldehyde. The nanoparticles show an average diameter of 42 nm, emit bright cyan fluorescence with high quantum yield, and exhibit high water dispersibility and excellent photostability. Due to the advantages, our polymer nanoparticles (PNPs) are utilized as a fluorescent probe for imaging in living SK-N-SH cells. Furthermore, valuable explorations have been carried out on the fundamental properties of PNPs, such as concentration-dependent fluorescence, pH-dependent fluorescence, and solvent effect.

New views on the reaction of primary amine and aldehyde from DFT study.

A general theoretical investigation on the reaction of primary amine with aldehyde was carried out by density functional theory. The calculation systems involve three kinds of primary amines (methylamine, vinylamine, and phenylamine) and three kinds of aldehydes (formaldehyde, acetaldehyde, and acrylaldehyde). The steric and electronic inductive effects on the reaction mechanism were studied. Results reveal that the nucleophilic attack of primary amine on aldehyde under neutral conditions leads to carbinolamines, rather than Schiff bases. The nucleophilic attack on the protonated aldehyde produces the protonated Schiff base. The steric hindrance of the aldehyde slows down the nucleophilic attack but allows enough time to abstract a H; consequently, the formation of the protonated Schiff base is preferred. During the carbinolamine protonation, the H(+) preferably locates on the amine nitrogen and then is abstracted by the hydroxyl oxygen over an energy barrier, leaving protonated Schiff base after timely water liberation. The formation of a prereaction potential energy well obviously softens the steric and electronic inductive effects on the active barrier for different reactants.

Development of a colorimetric sensor Array for the discrimination of aldehydes

A brand-new colorimetric sensor array was developed based on cross-reactive mechanism to discriminate 9 kinds of aldehydes and 16 volatile organic lung cancer biomarker candidates in low concentration. Sixteen out of twenty-seven dyes were selected to mix with 2,4-dinitrophenylhydrazine (DNPH) in optimized concentration to serve as specific sensing elements, and polyethylene glycol-1000 was chosen from four kinds polyethylene glycols to act as stabilizer. Resultant sensor array shows improved response (about tenfold higher) to aldehydes than former study, and exhibited very good selectivity in low concentration ranging from 40ppb to 10ppm with the presence of interfering counterparts. Data analysis was performed by both hierarchical cluster analysis (HCA) and discriminant analysis (DA), which demonstrates the excellent discrimination ability of the sensor to structurally similar aldehydes related to lung cancer. Besides, formaldehyde-spiked air samples were analyzed with developed sensor array, suggesting promising utilization potentiality to monitor such toxic gas. Theoretical detection limit was down to 8.2ppb with a liner range from 10ppb to 150ppm. The sensor array can be further developed for early diagnosis of lung cancer as well as monitoring of domestic and industrial formaldehyde pollution.

Decarbonylation of water insoluble carboxaldehydes in aqueous microemulsions by some sol–gel entrapped catalysts

In the course of our attempts to replace harmful solvents in organic processes by environmentally favored media, we investigated the use of aqueous microemulsions for catalytic decarbonylation of different kinds of aldehydes. The aldehydes were solubilized in the microemulsions with the aid of the cationic surfactant, cetyltrimethylammonium bromide. The aldehydes were transferred into CO-free products by sol–gel entrapped catalysts. The best results were obtained in the presence of nanoparticles of Pd(0). The heterogenized catalyst could usually be recycled 7–8 times without loss of catalytic activity. At relatively low temperatures (140°C) the decarbonylation proceeds stepwise. Initially a mixture of saturated and unsaturated products is formed. At 180°C however, fast hydrogenation of the unsaturated compounds takes place. These investigations may be regarded as model studies for the conversion of biomass derived intermediates to fuels and chemicals.

증류조건을 달리한 감자소주의 휘발성 성분

The fusel oils and the volatile flavor compounds of two potato sojues, one of which was produced with the traditional distillation apparatus(soju-gori) and the other, with the reduced pressure distillation system, were examined. The fusel oil content was high in the potato soju that was distilled under reduced pressure (potato soju(II)). The relative ratio of the isoamyl alcohol to the isobutyl alcohol and the n-propanol was 3.1:0.8:1.0 in the potato soju that was distilled with soju-gori (potato soju(I)), and 4.0:1.2:1.0 in potato soju(II). The chromatograms of the volatile components apparently differed between potato soju(I) and potato soju(II). Potato soju(I) contained four kinds of alcohol, six kinds of ester, n-valeraldehyde, and acetic acid. Potato soju(II) contained seven kinds of alcohol, 14 kinds of ester, two kinds of aldehyde, acetic acid, and three other compounds. Potato soju(II) significantly scored higher for flavor property than potato soju(I).