Gas Chromatography-mass Spectrometry Technology Research Articles

Unraveling Shengmuxiang in Jiang-flavor base baijiu using a combination of metabolomics and sensomics strategy

Shengmuxiang (SMX), an important aroma in Jiang-flavor base baijiu, significantly influences the quality of the product. This study employed untargeted metabolomics combined with sensomics to explore the key compounds responsible for SMX. Results indicated that SMX samples had higher intensities of green and woody-like odors compare to control samples. A total of 87 aroma compounds were identified by headspace solid phase microextraction combined with gas chromatography–mass spectrometry technology. Based on the variable projection importance, PCA and OPLS-DA were employed to identify 22 potential marker compounds. Quantitative results combined with hierarchical cluster and OAV analysis revealed that 9 aroma compounds (OAV > 1) had high concentrations in SMX samples. Aroma recombination and omission experiments further indicated that acetaldehyde and acetal were the key compounds responsible for the characteristic aroma of SMX in Jiang-flavor base baijiu. These findings provide valuable insights into the distinct aroma profile of SMX and offer a basis for quality control of Jiang-flavor base baijiu.

Interaction of composite fume suppression and odor elimination agents with crumb rubber modified asphalt: Inhibition behavior of volatile organic compounds (VOCs) and inorganic fume

The production and construction of crumb rubber modified asphalt (RMA) at high temperatures can produce a large amount of toxic fume, which is detrimental to human health and environment. In this study, a series of composite fume suppression and odor elimination agents (CSEAs) with both physical adsorption and chemical capture functions were adopted to reduce the emissions of volatile organic compounds (VOCs) and hydrogen sulfide (H2S). The material composition, microstructure, and specific surface area of CSEA were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and N2 adsorption-desorption isotherm (BET). The inhibitory effects of adding CSEA on toxic fume emissions from RMA at high temperatures were investigated through a combination of fume emission tests, H2S gas detection, gel permeation chromatography (GPC), and gas chromatography–mass spectrometry technology (GC–MS). The adsorption behavior of CSEA on H2S was analyzed through adsorption dynamics. Results showed that the physical and chemical properties of CSEA are stable while chemical adsorption dominates the CSEA's effect on H2S. ZnO and Ca(OH)2 exhibit good crystallization effects on the surface of the carrier by forming mesoporous structures mostly above 3.4 nm in size. The incorporation of CSEA significantly reduced the total emissions of RMA fume and the main components of VOCs in which the average inhibition rate of H2S can reach 44 % at an initial 30 mins.

The Characteristic Aroma Compounds of GABA Sun-Dried Green Tea and Raw Pu-Erh Tea Determined by Headspace Solid-Phase Microextraction Gas Chromatography-Mass Spectrometry and Relative Odor Activity Value.

We aim to improve the product quality of GABA raw Pu-erh tea during development and processing. In this study, headspace solid-phase microextraction gas chromatography-mass spectrometry technology combined with relative odor activity evaluations was used to compare the volatile compounds of GABA sun-dried green tea and GABA raw Pu-erh tea. Sensory evaluation showed a higher aroma score of GABA raw Pu-erh tea than that of GABA sun-dried green tea, with significant differences in aroma type and purity. A total of 147 volatile compounds of 13 categories were detected, which differed in composition and quantity between the two teas. 2-Buten-1-one,1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-,(E)- and beta.-myrcene largely contributed to the aroma formation of both teas. Five volatile compounds were screened as potential markers for tea aroma. Metabolic pathway analysis showed that monoterpenoid biosynthesis may be beneficial to the formation of flowery and fruity aromas in the teas. We suggest that the findings of this study may provide important guidance for the processing and optimization of GABA tea.

Correlation between fungi and volatile compounds during different fermentation modes at the industrial scale of Merlot wines

Elucidation of the relationship between fungal community development and dynamic changes in volatile components during fermentation is of great significance in controlling wine production. However, such studies on an industrial scale are rarely reported. In this study, fungal community succession during spontaneous fermentation (SPF) and inoculation fermentation (INF) of Merlot wine was monitored by a research strategy combining culture-dependent and culture-independent methods. The volatile compounds were monitored during SPF and INF by headspace solid-phase micro-extraction coupled with gas chromatography-mass spectrometry technology. The Spearman correlation coefficient was also used to investigate the interplay between fungal communities and volatile compounds. We found that fungal community diversity in SPF decreased as fermentation progressed but was significantly higher than that of INF. Starmerella and Kazachstania were the dominant non-Saccharomyces genera in Merlot wine during SPF. However, the presence of commercial yeasts and sulphur dioxide led to a sharp decrease or the disappearance of non-Saccharomyces genera during INF. Spearman correlation analysis revealed that all major volatiles were positively correlated with most functional microbiotas except P. fermentans, S. bacillaris, E. necator, and D. exigua in INF. In SPF, most non-Saccharomyces were negatively correlated with core volatiles, whereas K. humilis, M. laxa, P. kluyveri, and A. japonicus were positively correlated with the major volatiles, especially some higher alcohols (isopentol, heptanol) and terpenes (linalool, citronellol). S. cerevisiae was positively correlated with most of the main volatile substances except ethyl isovalerate and isoamyl acetate. These findings provide a reference for comprehending the diverse fermentation methods employed in the wine industry and improving the quality of Merlot wines.

Comparison of Metabolites and Species Classification of Thirteen Zingiberaceae Spices Based on GC-MS and Multi-Spectral Fusion Technology.

Due to a similar plant morphology in the majority of Zingiberaceae spices, substitution and adulteration frequently take place during the sales process. Therefore, it is important to analyze the metabolites and species classification of different Zingiberaceae spices. This study preliminarily explored the differences in the metabolites in thirteen Zingiberaceae spices through untargeted gas chromatography-mass spectrometry (GC-MS) and combined spectroscopy, establishing models for classifying different Zingiberaceae spices. On one hand, a total of 81 metabolites were successfully identified by GC-MS. Thirty-seven differential metabolites were screened using variable important in projection (VIP ≥ 1). However, the orthogonal partial least squares discriminant analysis (OPLS-DA) model established using GC-MS data only explained about 30% of the variation. On the other hand, the partial least squares discriminant analysis (PLS-DA) models with three spectral data fusion strategies were compared, and their classification accuracy reached 100%. Among them, the mid-level data fusion model based on latent variables had the best performance. This study provides a powerful tool for distinguishing different Zingiberaceae spices and assists in reducing the occurrence of substitution and adulteration phenomena.

Cytogenetic Characterization and Metabolomic Differences of Full-Sib Progenies of Saccharum spp.

Sugarcane smut is a worldwide fungal disease. Disease resistance breeding is the most economical and effective measure to prevent and control sugarcane smut. The cytogenetic characteristics and metabolomic differences of sugarcane F1s are closely related to disease resistance. Zhongzhe 1 and G160 sugarcane from the same parents (ROC25 and Yunzhe89-7) were used; the plants were grown in accordance with the barrel method. When the seedlings had 4-5 leaves, genomic in situ hybridization (GISH) was performed; digoxigenin (DIG)-labeled female parental (ROC25)DNA and biotin-labeled male parental (Yunzhe89-7) DNA were used as probes, and the karyotypes of two hybrids were analyzed. The new sugarcane smut-resistant variety (Zhongzhe 1) and the susceptible variety (G160) derived from the same parent were analyzed via gas chromatography-mass spectrometry technology (GC-MS) to compare the metabolomic differences between them. GISH analysis revealed that the chromosome ploidy number of Zhongzhe 1 sugarcane and G160 sugarcane were 114 and 110, respectively. However, the two contain different numbers of chromosomes from the female (ROC25) and male (Yunzhe89-7) parents. Moreover, 258 significantly changed metabolites were identified in smut-resistant Zhongzhe 1, as compared with the smut-susceptible G160 sugarcane: 56 flavonoids, 52 phenolic acids, 30 lipids, 26 organic acids, 26 amino acids and derivatives, 19 nucleotides and derivatives, 5 alkaloids, 9 terpenoids, and 35 others. Multivariate statistical analysis revealed a distinct difference in metabolic pathways between Zhongzhe 1 sugarcane and G160, and both of these varieties had unique functional metabolites. Differences in chromosome composition may constitute the genetic basis for the difference in resistance to smut disease between Zhongzhe 1 sugarcane and G160 sugarcane, and a high accumulation of flavonoids, lipids, terpenoids and tannins may constitute the basis of resistance to smut disease for the Zhongzhe 1 variety.

Gas Chromatography-Mass Spectrometry Technology: Application in the Study of Inflammatory Mechanism in COVID-19 Patients.

SARS-CoV-2 infection in the human body induces a severe storm of inflammatory factors. However, its specific mechanism is still not clear. Gas chromatography–mass spectrometry (GC–MS) technology is expected to explain the possible mechanism of the disease by detecting differential metabolites. 15 COVID-19 patients and healthy controls were included in this study. Immune indicators such as hs CRP and cytokines were detected to reflect the level of inflammation in patients with COVID-19. The distribution of lymphocytes and subpopulations in peripheral whole blood were detected using flow cytometry to assess the immune function of COVID-19 patients. The expression of differential metabolites in serum was analyzed using GC–MS non-targeted metabolomics. The results showed that hs CRP, IL-5/6/8/10 and IFN-α in the serum of COVID-19 patients increased to varying degrees, and CD3/4/8+ T lymphocytes decreased. Additionally, 53 metabolites in the serum of COVID-19 patients were up regulated, 18 metabolites were down regulated, and 8 metabolites remained unchanged. Increased Cholesterol, Lactic Acid and 1-Monopalmitin may be the mechanism that causes excessive inflammation in COVID-19 patients. The increase of D-Allose may be involved in the process of lymphocyte decrease. In conclusion, the significance of our study is to reveal the possible mechanism of inflammatory response in patients with COVID-19 from the perspective of metabolomics. This provided a new idea for the treatment of COVID-19.

Systematic impacts of fluoride exposure on the metabolomics of rats

Fluoride is widely present in the environment. Excessive fluoride exposure leads to fluorosis, which has become a global public health problem and will cause damage to various organs and tissues. Only a few studies focus on serum metabolomics, and there is still a lack of systematic metabolomics associated with fluorosis within the main organs. Therefore, in the current study, a non-targeted metabolomics method using gas chromatography-mass spectrometry (GC-MS) was used to research the effects of fluoride exposure on metabolites in different organs, to uncover potential biomarkers and study whether the affected metabolic pathways are related to the mechanism of fluorosis. Male Sprague-Dawley rats were randomly divided into two groups: a control group and a fluoride exposure group. GC-MS technology was used to identify metabolites. Multivariate statistical analysis identified 16, 24, 20, 20, 24, 13, 7, and 13 differential metabolites in the serum, liver, kidney, heart, hippocampus, cortex, kidney fat, and brown fat, respectively, in the two groups of rats. Fifteen metabolic pathways were affected, involving toxic mechanisms such as oxidative stress, mitochondrial damage, inflammation, and fatty acid, amino acid and energy metabolism disorders. This study provides a new perspective on the understanding of the mechanism of toxicity associated with sodium fluoride, contributing to the prevention and treatment of fluorosis.

Study on the Quality and Related Volatile Compounds of Beijing You- Chicken at Different Temperatures

Background: Beijing You-chicken with a unique flavor and rich nutrition is an excellent local chicken breed in China. Clarifying the change of volatile odor during the storage of chicken is helpful to assist in judging the freshness of chicken. Methods: The total viable count (TVC), total volatile basic nitrogen (TVB-N), lightness value L* and thiobarbituric acid reactive rubstances (TBARS) of chicken breast were measured at 4oC and 25oC, respectively. And the electronic nose and gas chromatography mass spectrometry (GC-MS) technology were used to determine the changes of volatile compounds during storage. Result: Significant changes of the volatile compounds were observed on first day at 25oC and the 8th day at 4oC of storage, which agreed with the results evaluated by detection of physicochemical indicators. The results of this study could serve as a theoretical basis for future research on detecting changes in chicken freshness by using the electronic nose and GC-MS technology.

Characterization of Aroma Volatiles in Xilin Fire Ginger Oils by HS-SPME-GC-MS

ABSTRACT Ginger is widely used as either a food product or a herbal medicine around the globe. In the current study, we used headspace solid-phase microextraction and gas chromatography-mass spectrometry technology (HS-SPME-GC-MS) with n-butyl acetate as an internal standard to characterize three kinds of ginger oil in Xilin fire ginger, which included ginger essential oil (GEO), ginger oleoresin extracted with petroleum ether (PEGO) and ginger oleoresin extracted with absolute ethanol (AEGO). Cluster analysis of heatmap was used to reveal the differences in concentration in these oils. Odor activity value, in combination with principal component analysis, was further used to analyze the contribution to the aroma. This study demonstrated that despite the similarities in the aroma compounds and content of three kinds of ginger oil, GEO exhibited a better aroma quality, followed by AEGO and PEGO.

Screening of Streptococcus thermophilus with Good Flavor and Analysis of Its Aroma Production Characteristics

As one of the main strains of fermented milk, Streptococcus thermophilus can impart excellent texture, rich nutritional value and unique flavor to fermented milk during the fermentation and storage process of fermented milk. On the basis of the previous research, 7 strains of S. thermophilus with good fermentation characteristics isolated from traditional fermented milk in different regions were used as the experimental strains this experiment, and commercial starters were used as the control group, solid phase microextraction was used combined with gas chromatography-mass spectrometry technology to detect and analyze the volatile flavor substances in the fermented milk at the end of the fermentation, which was pH4.5. The results showed that among all the experimental strains, the composition and content of volatile flavor compounds in G80-2 fermented milk were closest to the control group. On this basis, the dynamic analysis of the volatile flavor substances produced by the G80-2 strain during the fermentation and storage of milk was carried out. It was found that the strain was detected acids (4 types), alcohols (10 types), ketones (12 types), aldehydes (6 types), esters (1 type) and other compounds during fermentation and storage. Some main characteristic flavor substances such as acetic acid, acetaldehyde, diacetyl, acetoin, 2-heptanone, 1-heptanol, etc. were relatively high in content. It was concluded that the strain could be used as a starter in the production of dairy products.

Method validation for the determination of aniline and 3,3’-dichlorobenzidine by gas chromatography-mass spectrometry

This article uses and validates the analytical methods for the determination of aniline and 3,3’-dichlorobenzidine in soil by gas chromatography-mass spectrometry, and discusses the determination of semi volatile organic compounds in soil by gas chromatography-mass spectrometry. The feasibility of the application. The results showed that the semi volatile organic compounds aniline and 3,3’-dichlorobenzidine target corresponding to the internal standard response value and concentration showed a good linear relationship, the correlation coefficient was between 0.9997 and 0.9983 respectively; the detection limit was 0.04 mg, respectively/kg and 0.04mg/kg, the limits of quantification are 0.2mg/kg and 0.2mg/kg; the relative standard deviations of the two semi-volatile organic compounds in the precision are 2.5∼16.9% and 3.6∼6.2%, respectively; the accuracy is 2 The recovery rates of these volatile organic compounds were 64.5-83.9% and 72.6-74.3%, respectively. The verification results show that the linear relationship, detection limit, precision and accuracy all meet the requirements of “Determination of Semi-volatile Organic Compounds in Soils and Sediments by Gas Chromatography-Mass Spectrometry” (HJ 834-2017). Using gas chromatography-mass spectrometry technology can achieve fast, accurate and sensitive detection of target substances, and can meet the detection requirements of trace semi-volatile organic compounds, so this method can be better applied to the detection of soil and other environments.

The Potential Regulatory Network of Glutamate Metabolic Pathway Disturbance in Chinese Han Withdrawal Methamphetamine Abusers.

ObjectsTo explore the long-term influence of methamphetamine abuse on metabolomics character, with gas chromatography-mass spectrometry (GS-MS) technology, and the potential regulatory network using the bioinformatics method.MethodsForty withdrawal methamphetamine abusers (WMA) were recruited from Shanghai Gaojing Forced Isolation Detoxification Institute. Forty healthy controls (HC) were recruited from society. GS-MS technology was used to detect metabolic products in serum. A bioinformatics method was used to build a regulatory network. Q-PCR was used to detect the candidate gene expressions, and ELISA was used to detect the regulatory enzyme expressions.ResultsFour pathways were significantly changed in the MA compared to the HC: (1) the arginine synthesis pathway, (2) alanine, aspartic acid and glutamate metabolic pathway, (3) cysteine and methionine metabolic pathway, and (4) the ascorbate and aldarate pathway (enrichment analysis p < 0.05, Impactor factor > 0.2). When focusing on the ‘Alanine, aspartate, and glutamate metabolism’ pathway, a regulatory network was established, and the expression of candidate regulatory genes and enzymes was verified. It was found that the expression of DLG2 (Discs large MAGUK scaffold protein 2), PLA2G4 (Phospholipase A2 group IVE), PDE4D (Phosphodiesterase 4D), PDE4B (Phosphodiesterase 4B), and EPHB2 (Ephrin type-B receptor 2) were significantly different between the two groups (p < 0.05), However, after adjusting for age and BMI, only DLG2, PLA2G4, and EPHB2 remained significant (p < 0.05). The expression of enzymes was not significantly different (p > 0.05).ConclusionMethamphetamine abuse influences the metabolic process in the long term, and DLG2, PLA2G4, and EPHB2 may regulate the glutamate metabolism pathway.

Advances in high resolution GC-MS technology: a focus on the application of GC-Orbitrap-MS in metabolomics and exposomics for FAIR practices.

Gas chromatography-mass spectrometry (GC-MS) provides a complementary analytical platform for capturing volatiles, non-polar and (derivatized) polar metabolites and exposures from a diverse array of matrixes. High resolution (HR) GC-MS as a data generation platform can capture data on analytes that are usually not detectable/quantifiable in liquid chromatography mass-spectrometry-based solutions. With the rise of high-resolution accurate mass (HRAM) GC-MS systems such as GC-Orbitrap-MS in the last decade after the time-of-flight (ToF) renaissance, numerous applications have been found in the fields of metabolomics and exposomics. In a short span of time, a multitude of studies have used GC-Orbitrap-MS to generate exciting new high throughput data spanning from diverse basic to applied research areas. The GC-Orbitrap-MS has found application in both targeted and untargeted efforts for capturing metabolomes and exposomes across diverse studies. In this review, I capture and summarize all the reported studies to date, and provide a snapshot of the milieu of commercial and open-source software solutions, spectral libraries, and informatics solutions available to a GC-Orbitrap-MS system instrument user or a data analyst dealing with these datasets. Lastly, but importantly, I provide an account on data sharing and meta-data capturing solutions that are available to make HRAM GC-MS based metabolomics and exposomics studies findable, accessible, interoperable, and reproducible (FAIR). These FAIR practices would allow data generators and users of GC-HRMS instruments to help the community of GC-MS researchers to collaborate and co-develop exciting tools and algorithms in the future.

Metabolomics Benefits from Orbitrap GC-MS-Comparison of Low- and High-Resolution GC-MS.

The development of improved mass spectrometers and supporting computational tools is expected to enable the rapid annotation of whole metabolomes. Essential for the progress is the identification of strengths and weaknesses of novel instrumentation in direct comparison to previous instruments. Orbitrap liquid chromatography (LC)–mass spectrometry (MS) technology is now widely in use, while Orbitrap gas chromatography (GC)–MS introduced in 2015 has remained fairly unexplored in its potential for metabolomics research. This study aims to evaluate the additional knowledge gained in a metabolomics experiment when using the high-resolution Orbitrap GC–MS in comparison to a commonly used unit-mass resolution single-quadrupole GC–MS. Samples from an osmotic stress treatment of a non-model organism, the microalga Skeletonema costatum, were investigated using comparative metabolomics with low- and high-resolution methods. Resulting datasets were compared on a statistical level and on the level of individual compound annotation. Both MS approaches resulted in successful classification of stressed vs. non-stressed microalgae but did so using different sets of significantly dysregulated metabolites. High-resolution data only slightly improved conventional library matching but enabled the correct annotation of an unknown. While computational support that utilizes high-resolution GC–MS data is still underdeveloped, clear benefits in terms of sensitivity, metabolic coverage, and support in structure elucidation of the Orbitrap GC–MS technology for metabolomics studies are shown here.

Research of domanic source rock by pyrolytic gas chromatography-mass spectrometry method

We applied new novel approach based on pyrolytic gas chromatography-mass spectrometry technology (Py-GCMS) developed by Frontier Lab company (Japan) in order to get the same data as it can be acquired by using conventional core analyzer. Experimental part describes the detailed measurement procedure, temperature program and outcomes acquired by using IFP 160000 as a standard sample. We have managed to demonstrate accuracy and reproducibility of tests for the domanic source rock samples and its kerogen extracted respectively. In results of this analytical challenge we were able to get pyrograms providing the S1 (free hydrocarbons), S2 (potential hydrocarbons), Tmax (temperature at which the maximum rate of hydrocarbon generation is reached) information with level of confidence we usually could see doing conventional core analyzer tests. Some important conclusions regarding petroleum generation and thermal maturity have been made. S1 and S2 significantly decrease for kerogen samples with Tmax growth at the same time. Moreover mass spectra data of core samples pyrolizates can be collected easily to detect certain groups of compounds. Sulfur-containing compounds temperature extracted by Py-GCMS can be measured for example. Py-GCMS technology fully comply with mainstream analytical protocol for whole-rock or kerogen analysis and even more, Py-GCMS has a lot of advantages against conventional approach providing us additional valuable information about a sample.

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.

Gas chromatography-mass spectrometry based urinary metabolomics in very low birth weight premature infants

Objective: To investigate the urinary metabolic spectrum and pathways in very low birth weight (VLBW) premature infants. Method: A prospective case-control study was conducted to collect and compare the data of VLBW premature infants and full term infants from the Sixth Affiliated Hospital of Sun Yet-Sen University in 2014. Within 24 hours after birth, urine specimens in each group were collected. Metabolites of urine samples including amino acid, fatty acid and organic acid were detected using the urease pre-processing and gas chromatography mass spectrometry (GC-MS) technology. Using the orthogonal partial least squares discriminant analysis (OPLS-DA), the biomarkers and differences between the two groups were found. The online metabolic pathway website was explored and multivariable analysis was conducted to investigate the valuable pathways and biomarkers related to the prematurity. Result: A total of 20 VLBW premature infants were enrolled, among whom 11 were male, 9 were female; and 20 full term infants were enrolled, among whom 9 were male, 11 were female. The urinary metabolites were established and compared between the VLBW premature and term infants. The investigation showed that the following nine pathways were enriched: amino-acyl-tRNA biosynthesis(P=0.000), lysine degradation(P=0.007), fatty acid biosynthesis(P=0.008), pyrimidine metabolism(P=0.014), pantothenate and CoA biosynthesis(P=0.022), valine, leucine and isoleucine biosynthesis(P=0.022), lysine biosynthesis(P=0.031), glycerolipid metabolism(P=0.046), and valine, leucine and isoleucine degradation(P=0.031). Almost all the metabolites decreased except for the glyceric acid exhibiting a higher content in the VLBW premature infant. 12 potential biomarkers were explored with the most significant covariance and correlation, within which stearic acid, palmiticacid, myristic acid, β-amino-isobutyric acid, and uric acid were lower, while myo-inositol, mannitol, glycine, glucose1, glucose2, glyceric acid and N-acetyl-tyrosine were higher in the VLBW premature group compared with the control group. Conclusion: There is a significant difference between the VLBW premature infants and full-term infants in the metabolic state and pathways. The urease pre-processing and GC-MS technology followed by the OPLS-DA and multivariable analysis to investigate VLBW premature infants' urinary metabolites is a valuable method to evaluate the patients' metabolism.

Optimisation of steam distillation extraction oil from onion by response surface methodology and its chemical composition

Oil extraction from onion was performed by steam distillation. Response surface methodology was applied to evaluate the effects of ratio of water to raw material, extraction time, zymolysis temperature and distillation times on yield of onion oil. The maximum extraction yield (1.779‰) was obtained as following conditions: ratio of water to raw material was 1, extraction time was 2.5 h, zymolysis temperature was 36° and distillation time was 2.6 h. The experimental values agreed well with those predicted by regression model. The chemical composition of extracted onion oil under the optimum conditions was analysed by gas chromatography-mass spectrometry technology. The results showed that sulphur compounds, like alkanes, sulphide, alkenes, ester and alcohol, were the major components of onion oil.

Effect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish (Suan yu)

SummaryEffect of autochthonous starter cultures on the volatile flavour compounds of Chinese traditional fermented fish was studied. Lactobacillus plantarum 120, Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31, isolated from Suan yu, were selected as starter cultures. Volatiles were extracted by headspace solid‐phase microextraction (SPME) and analysed by gas chromatography–mass spectrometry technology (GC‐MS). Esters and alcohols were the main components of volatiles, accounting for over 50 percentage points in all samples. The highest content of esters (3034.54 μg kg−1) was observed in S1 inoculated with L. plantarum 120, while the highest content of alcohols (2164.53 μg kg−1) and ketones (379.98 μg kg−1) was detected in S3 inoculated with S. cerevisiae 31. The content of acids and aldehydes was lower in inoculated samples. Principal component analysis revealed that the volatile composition was primarily influenced by the nature of the starter cultures. L. plantarum 120 and S. xylosus 135 could accelerate fermentation.