Gas Chromatography-mass Spectrum Research Articles

CuO/zeolite catalyzed oxidation of gaseous toluene under microwave heating

The development of a combined process of catalytic oxidation and microwave heating for treatment of toluene waste gas was described in this work. Toluene, a typical toxic volatile organic compound, was oxidized through a fixed bed reaction chamber containing zeolite-supported copper oxide (CuO/zeolite) catalyst mixed with silicon carbide (SiC), an excellent microwave-absorbing material. The target compound was efficiently degraded on the surface of the catalyst at high reaction temperature achieved by microwave-heated SiC. A set of experimental parameters, such as microwave power, air flow and the loading size of CuO etc., were investigated, respectively. The study demonstrated these parameters had critical impact on toluene degradation. Under optimal condition, 92% toluene was removed by this combined process, corresponding to an 80%–90% TOC removal rate. Furthermore, the catalyst was highly stable even after eight consecutive 6-h runs. At last, a hypothetical degradation pathway of toluene was proposed based on the experimental data obtained from gas chromatography-mass spectrum and Fourier transform infrared spectroscopy analyses.

Chemical composition, in vitro antifungal and antioxidant activities of essential oil from Cotula coronopifolia L. growing in Tunisia

The chemical composition of Cotula coronopifolia L. essential oils obtained from the aerial parts (flowers, leaves, stems) and roots by hydro distillation was analyzed by gas chromatography/ mass spectrum (GC/MS). Fifty seven components were identified. The most important compound detected in leaves was Agarospirol (10.43%). Hexacosane was identified in flowers with an abundance percentage of (31.7%) and 1-Eicosanol (17.1%) in stem. The major constituents identified in the root oils were Heptacosane (28.4%), 1-Eicosanol (14.6%), Octacosane (5.4%), and γ Amorphen (5.2%). In vitro antioxidant activities of prepared essential oils were determined by using ABTS and DPPH methods and compared to those of the Trolox. Among the tested samples, flowers had the highest phenolic content with 22.02 mg equivalents Catechin/g of extract and roots presented the lowest phenolic content with 3.12 mg equivalents Catechin/g of extract. To evaluate in vitro antifungal activity, all volatile oils were tested against four fungi (two dermatophytes and two hyphamycets).

HS-SPME/GC-MS and chemometrics for volatile composition of Chinese traditional aromatic vinegar in the Zhenjiang region

The main purpose of this study was to determine the volatile composition of Zhenjiang aromatic vinegar, one of the four famous China-style cereal vinegars, by using headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrum (GC-MS) and chemometrics. For this purpose, the HS-SPME sampling method for the volatile compounds of Zhenjiang aromatic vinegar was optimized by a second-order rotatable central composite experimental design (CCD). A HS extraction of the volatile compounds by incubation on a 65 µm thickness polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre during 44.2 min at 69.5°C with 1.9 g NaCl add gave the most effective and accurate extraction. By the optimized method, a total of 58 volatile compounds, including 9 alcohols, 13 acids, 16 esters, 5 aldehydes, 4 ketones and 8 heterocycle compounds, were identified from 13 aromatic vinegar samples manufactured in Zhenjiang region. By principal components analysis (PCA), the thirteen vinegar samples were classified into 3 groups, and 10 volatile compounds were chosen as characteristic compounds of Zhenjiang aromatic vinegars. Copyright © 2012 The Institute of Brewing & Distilling

Characterization of structure and properties of polylactic fiber

AbstractPolylactic fiber (PLA) is a new environment‐friendly fiber and has been produced by different plants with wide application, while there are few studies on the difference of the structure and property of PLA fibers produced from these plants in China. The main content in present article is to conduct elementary analysis, gas chromatography mass spectrum, IR spectroscopy, ultraviolet, X‐ray, differential scanning calorimetry (DSC), TG, SEM, and tensile tests to obtain the common structure and properties of PLA fibers and to prove that there are no significant difference between the 13 kinds of PLA fibers made by 13 plants in China. The elementary analysis method is used to test the contents of C, H, and O elements, and it has good accordance with the theoretical results. Gas chromatography mass spectrum method proves that the functional groups of PLA fiber are lactide and acetaldehyde as well as 2,3‐pentanedione. IR spectroscopy depicts that significant absorbing peaks exist as CO, CO, OH within absorbing wavelength zones. There are no characteristic absorbing peaks of ultraviolet spectrum. Crystallinity and orientation degree in full wave at half maximum and in area are calculated based on X‐ray. The peak melting point and pyrogenation peak point are obtained by DSC and TG testings. The tensile property and the surface morphology by SEM are conducted and some typical faults in the surface are observed. In addition, the coefficient of variance of these experimental results between 13 kinds of PLA fibers show that their structure and properties are similar. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Characterization of the volatile profile of Brazilian Merlot wines through comprehensive two dimensional gas chromatography time-of-flight mass spectrometric detection

Wine aroma is an important characteristic and may be related to certain specific parameters, such as raw material and production process. The complexity of Merlot wine aroma was considered suitable for comprehensive two-dimensional gas chromatography (GC×GC), as this technique offers superior performance when compared to one-dimensional gas chromatography (1D-GC). The profile of volatile compounds of Merlot wine was, for the first time, qualitatively analyzed by HS-SPME-GC×GC with a time-of-flight mass spectrometric detector (TOFMS), resulting in 179 compounds tentatively identified by comparison of experimental GC×GC retention indices and mass spectra with literature 1D-GC data and 155 compounds tentatively identified only by mass spectra comparison. A set of GC×GC experimental retention indices was also, for the first time, presented for a specific inverse set of columns. Esters were present in higher number (94), followed by alcohols (80), ketones (29), acids (29), aldehydes (23), terpenes (23), lactones (16), furans (14), sulfur compounds (9), phenols (7), pyrroles (5), C13-norisoprenoids (3), and pyrans (2). GC×GC/TOFMS parameters were improved and optimal conditions were: a polar (polyethylene glycol)/medium polar (50% phenyl 50% dimethyl arylene siloxane) column set, oven temperature offset of 10°C, 7s as modulation period and 1.4s of hot pulse duration. Co-elutions came up to 138 compounds in 1D and some of them were resolved in 2D. Among the co-eluted compounds, thirty-three volatiles co-eluted in both 1D and 2D and their tentative identification was possible only due to spectral deconvolution. Some compounds that might have important contribution to aroma notes were included in these superimposed peaks. Structurally organized distribution of compounds in the 2D space was observed for esters, aldehydes and ketones, alcohols, thiols, lactones, acids and also inside subgroups, as occurred with esters and alcohols. The Fischer Ratio was useful for establishing the analytes responsible for the main differences between Merlot and non-Merlot wines. Differentiation among Merlot wines and wines of other grape varieties were mainly perceived through the following components: ethyl dodecanoate, 1-hexanol, ethyl nonanoate, ethyl hexanoate, ethyl decanoate, dehydro-2-methyl-3(2H)thiophenone, 3-methyl butanoic acid, ethyl tetradecanoate, methyl octanoate, 1,4 butanediol, and 6-methyloctan-1-ol.

Bioactive constituents of Homalomena aromatica essential oil and its antifungal activity against dermatophytes and yeasts

Homalomena aromatica rhizomes are rich source of essential oils, which have been attributed for various medicinal uses. In the present investigation, essential oil from H.aromatica rhizomes was isolated and subjected to gas chromatography-mass spectrum (GC-MS) analysis. Fifty-five chemical constituents were reported from H.aromatica rhizomes of which T-muurolol (5.32%), viridiflorol (3.69%), α-selinene (2.19%), M-cymene (2.19%) and γ-Muurolene (1.81%) were identified and reported for the first time. Other major components were identified as linalool (62.5%), terpene-4-ol (7.08%), δ-cadinene (5.57%), α-cadinol (3.71%) and spatulenol (1.81%). H.aromatica rhizome essential oil showed high antimicrobial activity against Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum fulvum, Microsporum gypseum, Trichosporon beigelii and Candida albicans.

Carbonyl Reduction of Cyclohexanone Derivatives Catalyzed by Recombinant Strain <i>Escherichia coli</i> BL21 (pET-<i>eryKR1</i>)2

In order to find substrate specificity and enantioselectivity of ketoreductase domain (EryKR1) in the first module of polyketide synthase from Saccharopolyspora erythraea, the whole cells of recombinant Escherichia coli BL21 (pET-eryKR1)2 harboring eryKR1 gene fermented with different kinds of cyclohexanone derivatives such as methylcyclohexanone and cyclohexanedione. Gas Chromatography (GC) or Gas Chromatography Mass Spectrum (GC-MS) analyses of these ferments indicate that when the recombinant cells were employed as biocatalysts, only one carbonyl of 1,2-cyclohexanedione and 1,4-cyclohexanedione could be reduced with the conversion rate 20.44% and 6.03%, respectively. In addition, 2-methylcyclohexanone and 3-methylcyclohexanone except 4-methylcyclohexanone could be significantly turned over by the recombinant cells to their corresponding cis-methylcyclohexanols, of which the conversion rate of 40 mM 2-methylcyclohexanone was 12.2% and enantiomeric excess of cis-2-methylcyclohexanol was 57.98%, and the conversion rate of 10 mM 3-methylcyclohexanone was 38.26% and enantiomeric excess of cis-3-methylcyclohexanol was 53.9%. Furthermore, the unexpected reduction of 1,2-cyclohexanedione and 2-chlorocyclohexanone by the control E.coli BL21 (pET-28a) reveals that the attracting electron effect induced by the carbonyl or chlorin group in their ortho position could make some NAD(P)H-dependent oxo-reductase except EryKR1 domain within the recombinants reduce the carbonyl of 1,2-cyclohexanedione and 2-chlorocyclohexanone. Therefore, it is concluded that 1,4-cyclohexanedione, 2-methylcyclohexanone and 3-methylcyclohexanone except 1,3-cyclohexanedione and 4-methylcyclohexanone are accepted substrates of EryKR1 domain which takes on a certain biocatalyst activity and stereospecificity.

Characterization of the effects of lignin and lignin complex particles as filler on a polystyrene film

The work in this research outlines the use of lignin precipitated from lignocellulosic substrate as fillers after modified with transition metal cations, Fe(III), Ni(II) and Co(II), in the production of a polystyrene based composite for polymer packaging applications. Virgin polystyrene was compared with lignin and lignin complex filled composites with loading of 5% by weight prepared using twin screw extrusion. The lignin complexes were first characterized by the UV spectra to identify the new absorption bands occurred due to the complex formation. Moreover, lignin model, namely vanillin, was used to notify the geometric structure of the resulting complexes applying the GC mass spectra. Scanning electron microscopy was used to indicate the change in the morphological structure of the filler particles. On the other hand, the mechanical and thermal analysis for the resulting polymer composites was studied and it was noticed that the type of lignin or lignin complex plays a roll in the results. The inclusion of the Co(II)–lignin complex was observed to increase the tensile strength of the resulting polymer composite and a decrease of the glass transition temperature. Furthermore, light wave lengths and UV fluorescent microscope were used to identify the change of color for the resulting polymer film.

Isolation and Anti-Fatty Liver Activity of a Novel Cerebroside from the Sea CucumberAcaudina molpadioides

Cerebrosides are a kind of important bioactive substance in sea cucumber. A novel cerebroside, AMC-2, was purified from the less-polar lipid fraction of the sea cucumber Acaudina molpadioides by repeated column chromatography. The major structure of AMC-2 was analyzed by gas chromatography-mass spectra. The amide-linked fatty acid unit was confirmed to be four saturated and monounsaturated α-hydroxy fatty acids, the long-chain base was dihydroxy sphingoid base with one double bond, and the glycosyl group was glucose. We also investigated the anti-fatty liver activity of AMC-2 in rats with fatty liver induced by orotic acid. AMC-2 significantly reduced hepatic triglyceride (TG) and total cholesterol (TC) levels at a diet supplement of 0.03% and 0.006%. The indexes of stearoyl-CoA desaturase (SCD) activity and mRNA expression were significantly decreased by AMC-2. This indicates that AMC-2 ameliorated nonalcoholic fatty liver disease (NAFLD) through suppression of SCD activity and impaired the biosynthesis of monounsaturated fatty acids in the livers of the rats.

Photocatalytic degradation of dimethoate using LbL fabricated TiO 2/polymer hybrid films

Degradation of dimethoate under UV irradiation using TiO 2/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of lamp intensity, catalyst loading in the layers, number of bilayers, pH and initial dimethoate concentration on the degradation of dimethoate was systematically studied. The degradation was monitored using high performance liquid chromatography (HPLC) analysis and total organic carbon (TOC) measurements as a function of irradiation time, to see the change in concentration of dimethoate and mineralization, respectively. Complete degradation of dimethoate was achieved under TiO 2 optimum loading of 4 g/L at an UV irradiation time of 180 min. Increase in the lamp intensity, catalyst loading and number of bilayers increased the rate of degradation. At a pH of 4.62, complete degradation of dimethoate was observed. The degradation efficiency decreased with increase in initial dimethoate concentration. The degradation byproducts were analyzed and confirmed by gas chromatography–mass spectra (GC–MS). Toxicity of the irradiated samples was measured using the luminescence of bacteria Vibrio fischeri after 30 min of incubation and the results showed more toxicity than the parent compound. Catalyst reusability studies revealed that the fabricated thin films could be repeatedly used for up to ten times without affecting the photocatalytic activity of the films. The findings of the present study are very useful for the treatment of wastewaters contaminated with pesticides.

Characterization of volatile compounds from Daqu‐a traditional Chinese liquor fermentation starter

SummaryDaqu is a fermentation starter and substrate complex that is used to initiate the solid fermentations for the production of Chinese liquor. The aroma of Daqu is one of the most important factors that influence the flavour of Chinese liquor. To further study the aroma of Daqu, volatile compounds in ten Daqu samples were extracted by headspace solid‐phase microextraction (HS‐SPME) and analysed by gas chromatography–mass spectrum (GC‐MS). The samples were pre‐equilibrated at 50 °C for 10 min and extracted with stirring at the same temperature for 30 min prior to injection into a GC‐MS. A total of 75 volatile compounds were characterised by GC‐MS, including twelve alcohols, eleven esters, eight acids, nine aromatic compounds, four phenols, two furans, fourteen nitrogen‐containing compounds and fifteen aldehydes and ketones. By a principal component analysis (PCA), the ten Daqu samples could be classified into three groups according to their origins and, in particular, the production technologies.

Isolation and application of a wild strain photosynthetic bacterium to environmental waste management

A new photosynthetic bacterium isolate was morphologically identified as a non-motile rod-shape gram-negative bacterium. It produced a dark red culture under phototrophic condition, reproduced by budding and formed a lamellar intracytoplasmic membrane system parallel to cytoplasmic membrane, which contained bacteriochlorophyll a and caratenoids. It's physiological and nutrient requirement tests gave indication that the isolate thrived and multiplied in varied environmental conditions. It was consequently named Z08 and identified as Rhodobacter sphaeroides by 16SrDNA. Adaptation of Z08 to biodegradation of two environmentally concerned wastewaters, i.e. soybean and pharmaceutical wastewaters, attested its potential in wastewater bioremediation. Z08 adaptation in a suspended batch photobioreactor treating pharmaceutical wastewater at 3500lx radiation recorded best result after wastewater dilution of 1:4 with concomitant chemical oxygen demand reduction, biomass yield and specific growth of 50 %, 780 mg/L and 0.015/h, respectively at the lowest hydraulic retention time of three days. Furthermore, gas chromatography mass spectra analyses of treated and raw pharmaceutical wastewater indicated that high molecular weight recalcitrant compounds found in the pharmaceutical wastewater were transformed to less toxic and acceptable lower molecular weight substances through biodegradation. Whilst Z08 treatment of soybean wastewater under natural light intensity radiation recorded 80 % reduction, 1540 mg/L and 0.025/h for chemical oxygen demand, biomass and specific growth rate respectively regardless of the food to microorganism ratio. This preliminary investigation showed that isolate Z08 has some toxic tolerance level which could detoxify refractory substances with great potential for cell protein recovery in high organic strength wastewater. Therefore, strain Z08 could be employed in biodegradation of contaminated wastewater streams.

Chemotaxonomy of six Salvia species using essential oil composition markers

Chemotaxonomy of six Salvia L. species in Iran has been controversial. The group includes the taxa Salvia atropatana Bunge., Salvia oligophylla Auch. ex Benth., Salvia aethiopis L., Salvia sclarea L., Salvia reuterana Boiss., Salvia macrosiphon Boiss., of which Salviareuterana and Salvia oligophylla are endemic to Iran. The essential oils obtained from aerial parts of species were analyzed by using gas chromatography (GC) and gas chromatography- mass spectrum (GC-MS). Two hundred and seventy components were analyzed and cluster analysis of oil components was done by average linkage. The results showed that S. oligophlla and S. aethiopis separated, due to its high amount of occidentotal,iso- Longifolene, β- Acoradiene, in S. oligophylla. Similarity in essential oil composition of the S. aethiopis and S. sclarea grouped them to one sub cluster. Also, a comparison of these results with previous works on Salvia species revealed that the major constituents of these taxa are different. Evidence from volatile oil compounds may have contributed to environmental factors such as available water and other climatic factors. Key words: Salvia, volatile constituent, chemotaxonomy, Lamiaceae, Iran.

Qualitative Characterization and Identification of Polylactic Fiber based on GC-MS, IR and Element Analysis

Polylactic fiber is a new renewable and biodegradable polymer material for its better physical property and thermoplastic and biological properties, while there are no corresponding inspection method to characterize and identify polylactic fiber with other fibers. So, the present paper is to qualitative analyze the features of PLA fiber and identify it with general fibers, including Polyester, Polyamide, Polyacrylic, Diacetate, Cotton, Viscose and Silk fibers. Elementary analysis method is utilized to have the definite analysis of fiber purity degree and category by the corresoponding element contents of constructing elements. The experimental results show that there exist good accordance with the theoretical results, and is suitable for qualitative characterizaion and identification of fibers. Gas chromatography mass spectrum method is used to feature marker functional groups of these eight fibers, and to further have a qualitative analysis of each fiber. IR spectroscopy proves the qualitative identification on fiber category by the marker absorbing peaks of functional groups ranging from 650cm-1-2200cm-1. These results will be greatly helpful in the qualitative analysis and indectification of Polylactic fiber.

Analysis of Characters and Structures of Polylactic Fiber

Polylactic fiber is a new environment-friendly fiber and has wide application, while there are few studies on its characters and structures. The main content in present paper is to analyze element content and functional group as well as thermal properties. The elementary analysis method shows that the contents of C, H and O elements are 49.83%, 5.63% and 44.54%, respectively; it has good accordance with the theoretical results. Gas chromatography mass spectrum method proves that the functional groups of PLA fiber are lactide and acetaldehyde as well as 2,3-pentanedione, and whose total content is larger than 70%. IR spectroscopy depicts that there exist significant absorbing peaks by -C=O-, -C-O-, -OH- within 1000cm-1-1300cm-1, and -C=O- within 1000cm-1-1300cm-1. The absorbing peak of ultraviolet spectrum is 260 nm avelength. Crystallinity is 61.72% and orientation degree is 93.36% and 84.30% in Full Wave at Half Maximum and in Area calculations based on X-ray. These results will be greatly helpful in the qualitative analysis and indectification of Polylactic fiber.

Identification of Components of the Female Sex Pheromone of the Simao Pine Caterpillar Moth, Dendrolimus kikuchii Matsumura

The pine caterpillar moth, Dendrolimus kikuchii Matsumura (Lepidoptera: Lasiocampidae), is a pest of economic importance on pine in southwest China. Three active compounds were detected during analyses of solvent extracts and effluvia sampled by solid phase microextraction (SPME) from virgin female D. kikuchii using gas chromatography (GC) coupled with electroantennographic (EAG) recording with antennae from a male moth. The compounds were identified as (5Z,7E)-5,7-dodecadien-1-yl acetate (Z5,E7-12:OAc), (5Z,7E)-5,7-dodecadien-1-ol (Z5,E7-12:OH), and (5Z)-5-dodecenyl acetate (Z5-12:OAc) by comparison of their GC retention indices, mass spectra, and EAG activities with those of synthetic standards. Microchemical reactions of gland extracts provided further information confirming the identifications of the three components. Solvent extractions and SPME samples of pheromone effluvia from virgin calling females provided 100:18:0.6 and 100:7:1 ratios of Z5,E7-12:OAc:Z5,E7-12:OH:Z5-12:OAc, respectively. Field behavioral assays showed that Z5,E7-12:OAc and Z5,E7-12:OH were essential for attraction of male D. kikuchii moths. However, the most attractive blend contained these three components in a 100:20:25 ratio in a gray rubber septa. Our results demonstrated that the blend of Z5,E7-12:OAc, Z5,E7-12:OH, and Z5-12:OAc comprise the sex pheromone of D. kikuchii. The optimized three-component lure blend is recommended for monitoring D. kikuchii infestations.

Antimicrobial essential oils of Bunium elegans and Bunium caroides

The essential oils of two plants of the genus Bunium called the common name Zireh in Persian have been analyzed using GC, GC/MS and 13C NMR spectroscopy. The oils were subjected to antibacterial activity tests. The essential oils have been extracted using hydro-distillation method. The Oils were subjected to analytical GC and GC/MS. The components of the oils were identified using GC retention indices and mass spectra. Identification of the main components was confirmed by NMR spectral data. The oils were then subjected to antibacterial test against Bacillus subtilis by agar disk diffusion method. The oils were found to be rich in sesquiterpenoids such as garmacrene D and caryophyllene and phenyl propanoids e.g. myristicin and dill apiol. In this paper, we will compare the constituents of the oils of B. elegans and B. caroides. The results show that the oils have similar constituents and this indicates that the plants are taxonomically similar.

Isolation and characterization of a Pseudomonas sp. strain IITR01 capable of degrading α-endosulfan and endosulfan sulfate

To isolate bacteria capable of degrading endosulfan (ES) and the more toxic ES sulfate and to characterize their metabolites. A Pseudomonas sp. strain IITR01 capable of degrading α-ES and toxic ES sulfate was isolated using technical-ES through enrichment culture techniques. No growth and no degradation were observed using β-ES. Thin-layer chromatography and gas chromatography-mass spectrum analysis revealed the disappearance of both α-ES and ES sulfate and the formation of hydroxylated products ES diol, ether and lactone. We show here for the first time the formation of aforementioned metabolites in contrast to ES hemisulfate yielded by an Arthrobacter sp. Metabolism of α-ES and endosulfate was also observed using the crude cell extract of IITR01. The molecular mass of protein induced during the degradation of α-ES and sulfate as substrate was found to be approximately 150 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We describe characterization of bacterium capable of degrading α-ES and ES sulfate but not β-ES. Genetic investigation suggests that a gene nonhomologous to the reported esd may be present in the strain IITR01. This study describes toxic ES degradation by a Pseudomonas species that may be utilized for the bioremediation of the industrial soils contaminated with ES residues.

Identification of petroleum aromatic fraction by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) is commercially available in the 1990s, with the characteristics of large peak capacity, high resolution, high sensitivity, etc. However, its application to the petroleum and geological analyses is just emerging in China and overseas. In this research, the analytical method for petroleum aromatic fraction using GC×GC-TOFMS is set up, via the choice of the column system and optimization of setting parameters, such as temperature programming, modulation time, hot pulse time, flow rate of carrier gas, data acquisition rate and data processing. The results indicate that different polar compounds of aromatic fraction distribute as bands on structured GC×GC chromatogram. Within each band, homologous compounds appear as a roof-tile structure based on the number of substituent residues. The aromatic compounds are identified and characterized according to the GC×GC chromatogram and mass spectra. According to the polarity and the number of rings, aromatic compounds are spatially present on one chromatogram, which directly reflects the distribution characteristics of complex compounds of aromatic hydrocarbons. In addition, quantitative analysis is favored as some overlapped peaks on traditional GC-MS chromatogram have been separated completely on GC×GC. Some heterocyclic atom aromatic compounds at trace level can be clearly identified using this method, for polarity differences from other interfered aromatic compounds. The development of this method and chromatogram recognition offer petroleum geologists a practical example for the application performance of GC×GC-TOFMS.

Ferulic Acid Release and 4-Vinylguaiacol Formation during Chinese Rice Wine Brewing and Fermentation

The release of ferulic acid (FA) and the subsequent enzymatic decarboxylation to 4-vinylguaiacol (4-VG) were nearly ubiquitous during the production of Chinese rice wine. To evaluate the release of FA and the transformation to 4-VG, the levels of FA and 4-VG were determined by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrum (GCMS), respectively. During rice wine brewing, the concentrations of FA and 4-VG increased as fermentation time prolonged, with a rapid rise in days 1 to 5 of the main fermentation and followed by a slower rise from the 6th day post inoculation. FA and 4-VG levels in mashes, fermented by yeast with wheat Qu, were significantly higher than those in mashes fermented by yeast using commercial enzyme additions. The release of FA from rice by wheat Qu involves an enzymatic release mechanism. The levels of FA and 4-VG from rice flour by wheat Qu rose gradually during the first 24 h and then tended to stabilize. The capacity of yeasts to decarboxylate phenolic acids (Pof + phenotype) was absent in most rice wine brewing yeasts. These results suggest that the production of FA and 4-VG originated from materials in the wheat Qu rather than by the yeast during Chinese rice wine brewing and fermentation.