•Total of 274 volatile compounds were identified in CB and HB tomato pastes.•The aroma compounds extracted by SAFE in CB tomato paste were more abundant than HB.•10 aroma-active compounds were ...detected for the first time in tomato pastes.•9 volatiles were identified for the first time in tomato pastes.•More compounds were identified using GC × GC-O-TOF-MS compared with GC-O-MS.
GC × GC-O-TOF-MS and GC-IMS have attracted increasing attention in complex food flavor analysis due to their high resolution and sensitivity. However, very few studies have attempted to identify the aroma components of tomato pastes through these techniques. Herein, the present study comprehensively characterized the aroma profiles of cold and hot break tomato pastes using SAFE-GC-O-MS, SAFE-GC × GC-O-TOF-MS, and HS-GC-IMS for the first time. A total of 274 volatile compounds were identified, far more than previously reported. About 87 % of these compounds can be identified by GC × GC-O-TOF-MS, exceeding 6 times that of GC-O-MS. Notably, 10 aroma-active compounds and 9 volatiles were identified by GC × GC-O-TOF-MS and HS-GC-IMS for the first time. The AEDA and OAVs results indicated that β-damascenone, linalool, 3-ethylbutanoic acid, and nonanal were the most powerful aroma-active compounds. These findings will provide deeper insights into improving the sensory quality of tomato paste.
In this work, a solid-phase microextraction (SPME) method combined with two-dimensional gas chromatography coupled to mass spectrometry (GC × GC-MS) was optimized and used to assess the authenticity ...of pomegranate juice to prevent fraudulent practices. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for the extraction of the volatiles. The critical parameters that affect the extraction process, such as the sample volume, and the extraction time were studied. The optimized protocol involved the addition of 15 mL of juice in 50 mL vial and saturation with 30% w/v NaCl.The extraction was carried out within 45 min under 1000 rpm stirring and was applied in the analysis of real juice samples to assess authenticity and detect low levels of pomegranate juice adulteration with grape and apple juice down to 1%. Commercially available pomegranate juice samples were acquired (n1 = 6) and adulterated with 1% of apple juice (n2 = 6), 1% of grape juice (n3 = 6), and a mixture of 1% apple juice and 1% grape juice (n4 = 6). Authentic pomegranate juice samples and adulterated mixtures were analyzed by SPME-GC × GC-MS. The analysis resulted in the identification of 123 volatile compounds that were further processed with chemometric tools. Principal component analysis (PCA) was employed to visualize the clustering of the samples, and a two-way orthogonal partial least squares discriminant analysis (O2PLS-DA) chemometric model was developed and successfully classified the samples to authentic pomegranate juice or adulterated with an explained total variance of 87.4%. The O2PLS-DA prediction model revealed characteristic volatile markers that could be used to detect pomegranate juice fraud.
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•Optimized SPME method combined with GC × GC-MS to address food fraud.•2D-GC volatilomics for the exploration of the fingerprint of juices.•Chemometrics successfully discriminated between pure pomegranate juices and adulterated.•Identification of characteristic volatile markers.
•Skatole, sclareololide and sclareololide were first identified in Laoshan tea.•Co-eluted compounds (furfural, cis-linalool oxide) were separating by GC × GC-qMS.•The interactions exist among aroma ...compounds in tea samples.
To investigate the key aroma compounds in Laoshan green teas (Huangshan (S1), Changling (S2), and Fangling (S3)), gas chromatography-mass spectrometry-olfactometry (GC-MS-O), a flame photometric detector (FPD), odor activity value (OAV), and comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-qMS) were employed. A total of 50 aroma compounds were perceived and 24 compounds were identified as important compounds related to OAV, such as dimethyl sulfide (OAV: 126–146), skatole (OAV: 27–50), furaneol (OAV: 8–27), (Z)-jasmone (OAV: 16–23), 2-methylbutanal (OAV: 15–22), and 3-methylbutanal (OAV: 68–87). Furthermore, the S-curve method was used to research the effect of aroma compounds on the threshold of aroma recombination (AR). The AR thresholds decreased from 3.8 mL to 0.45, 0.66, 0.93, 0.95, 0.75, 1.09, 3.01, and 2.57 mL after addition of eight compounds (skatole, furaneol, (Z)-jasmone, α-damascenone, sclareololide, dihydroactinidiolide, vanillin, and δ-valerolactone), indicating that those compounds (OAV >1) were contributors to the overall aroma of Laoshan teas.
Comprehensive two-dimensional gas chromatography (GC × GC) offers increased peak capacity and selectivity relative to conventional one dimensional separations. The analysis of persistent organic ...pollutants in environmental matrices is very challenging due to the large number of compounds with varying chemical and physical properties that are typically present in the sample at the same time at concentrations ranging from ultra-trace to percent levels. GC × GC is steadily gaining in popularity in environmental analysis and the number of publications citing the use of this technique has been increasing significantly in the recent years. An overview of the latest applications in the environmental field is presented in this paper, emphasizing the advances for targeted and non-targeted analysis in complex matrices. In addition, instrumentation, data interpretation approaches, as well as the quality assurance and control for routine analyzes are discussed.
•GC × GC offers increased peak capacity and selectivity compared to 1D GC.•The method is particularly useful in environmental analysis.•The latest applications of GC × GC in environmental analysis are reviewed.•Both targeted and non-targeted approaches are discussed.
Due to excellent separation capacity for complex mixtures of chemicals, comprehensive two-dimensional gas chromatography (GC × GC) is being utilized with increasing frequency for metabolomics ...analyses. This review describes recent advances in GC × GC method development for metabolomics, organismal sampling techniques compatible with GC × GC, metabolomic discoveries made using GC × GC, and recommendations and best practices for collecting and reporting GC × GC metabolomics data.
•The excellent separation capacity of GC × GC is well suited for metabolomics.•Methods are being developed to optimize metabolome sampling and analysis.•GC × GC metabolome analyses are moving toward identifying mechanisms.•Data reporting recommendations are provided to optimize data sharing via new metabolomics databases.•Best practices for GC × GC metabolomics analyses are described.
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•A novel Es-GC×GC-TOFMS approach to separate chiral volatiles in tea was established.•Volatile enantiomers in Wuyi rock teas from four cultivars were firstly quantitated.•Limits of ...quantitation of linalool oxides A−B in teas were as low as 0.2 pg/mL.•R-α-Ionone, S-(E)-nerolidol etc. were the potential markers to distinguish cultivar.•7 Volatile enantiomers were identified as aroma-active compounds in Wuyi rock teas.
Chiral volatiles play important roles in the formation of aroma quality of foods. To date, enantiomeric characteristics of chiral volatiles in Wuyi rock tea (WRT) and their aroma contributions are still unclear. In this study, an efficient enantioselective comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (Es-GC × GC-TOFMS) approach to separate and precisely quantitate 24 pairs of chiral volatiles in WRTs was established, and the enantiomeric distribution and aroma contribution of chiral volatiles among WRTs from four representative cultivars were investigated. Enantiomeric ratio (ER) of R-α-ionone (80%) in Dahongpao (DHP), ER of S-α-terpineol (57%) in Jinfo (JF), ERs of R-γ-heptanolactone (69%), S-γ-nonanolactone (55%), (2R, 5S)-theaspirane B (91%), concentration of S-(E)-nerolidol (313.37 ng/mL) in Rougui (RG) and concentration of R-α-ionone (33.01 ng/mL) in Shuixian (SX) were unique from other types of WRTs, which were considered as the potential chemical markers to distinguish WRT cultivars. The OAV assessment determined 7 volatile enantiomers as the aroma-active compounds, especially R-α-ionone and R-δ-octanolactone in SX, as well as S-(E)-nerolidol and (1R, 2R)-methyl jasmonate in RG contribute much to aroma formation of the corresponding WRTs. The above results provide scientific references for discrimination of tea cultivars and directed improvement of the aroma quality of WRT.
Flavor is an important attribute of food and a major factor that determines the acceptability of food to consumers. Therefore, achieving a comprehensive and accurate analysis of food flavor could ...provide insights into continuous exploration in food research. In recent years, the generation of comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) with excellent separation ability has successfully revealed the aroma compound composition in a complex food matrix. Meanwhile, GC×GC-MS combined with gas chromatography-olfactometry (GC-O) has been further developed in the combination of instrumental analysis and sensory evaluation. In this paper, a comprehensive review of the generation and development of GC×GC-MS was reported. Simultaneously, the principle of GC×GC-MS and the application progress of GC×GC-MS combined with GC-O in the flavor analysis field in recent years were summarized. Last, a new switchable system between GC-O-MS and GC×GC-O-MS (SGC/GC×GC-O-MS) was proposed to promote its further application in the flavor analysis of complex matrix foods.
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•The principle, development and application (last 5 years) of GC×GC-O were reviewed.•The advantages and disadvantages of several typical GC×GC-O models are discussed.•A switchable GC/GC×GC-O-MS was proposed to solve the disadvantages of GC×GC-O.•The application of switchable GC/GC×GC-O-MS was discussed to prove its feasibility.
•Total of 198 volatile compounds were identified in five commercial grilled lamb shashliks.•Characterizing commercial shashliks flavor by intelligent sensory technology.•Predicting the concentrations ...of eight classes of VOC and commercial shashliks brands.•The MDBN models achieved a better predictive performance than other models.
HS-SPME-GC-MS, SPME-Arrow-GC × GC-TOF-MS, HS-GC-IMS, Electronic-nose, and Electronic-tongue systems were applied in a feasibility study of the flavor characterization of five commercially available Chinese grilled lamb shashliks. A total of 198 volatile organic compounds (VOCs) were identified (∼71% by GC × GC-TOF-MS). Using data fusion strategies, five predictive models were applied to the composition of VOCs and brand identification of the lamb shashliks. Compared with partial least squares regression, support vector machine, deep neural network, and RegBoost modeling, a momentum deep belief network model performed best in predicting VOCs content and identifying shashlik brands (R2 above 0.96, and RMSE below 0.1). Intelligent sensory technology combined with chemometrics is a promising approach to the flavor characterization of shashliks and other food matrices.
•A method for the separation of saturated, monounsaturated and aromatic hydrocarbons is proposed.•It is an extension of the on-line HPLC–GC method for the analysis of mineral oil hydrocarbons.•A ...silver-impregnated silica gel HPLC column with a low amount of silver ions was prepared in the laboratory.•Saturated and monounsaturated polyolefin oligomers are determined in extracts of polyolefin granulates and foods.
Multidimensional chromatography based on two-dimensional high performance liquid chromatography on-line coupled to gas chromatography (on-line HPLC–HPLC–GC) enables the separate analysis of saturated, monounsaturated and aromatic hydrocarbons in packaging materials like polyolefins or paperboard and their migrates into foods. Since normal-phase HPLC on silica gel did not preseparate saturated from monounsaturated hydrocarbons, a separation step on a normal-phase HPLC column treated in the laboratory with an optimized amount of silver nitrate was added. The preparation of this HPLC column and the instrumental set-up are described, followed by examples showing the potential of the method. In a preliminary investigation of 11 polyolefin granulates for food contact up to 40% monounsaturated hydrocarbons among the oligomers C16–35 were determined.
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