Development of a solid phase microextraction protocol for the GC–MS determination of volatile off-flavour compounds from citral degradation in oil-in-water emulsions

The conditions for headspace solid phase microextraction (HS-SPME) analysis of volatile off-flavour compounds in citral emulsion were determined. Type of SPME phase (65 μm PDMS/DVB, 100 μm PDMS and 75 μm CAR/PDMS), adsorption temperature and salt concentration were significant factors affecting total peak area in the gas chromatogram and optimised in one factor experiments. Then, adsorption temperature (30–50 °C), adsorption time (20–40 min), and salt concentration (0–6 M) were studied to develop HS-SPME condition for obtaining the highest extraction efficiency. PDMS/DVB in 65 μm was the optimum fiber because of high adsorption efficiency and good reproducibility. The optimal condition was adsorption at 50 °C for 40 min and 6 M salt added to sample. Good Linearity, high recovery, good reproducibility and low limit of detection (LOD) for all off-odour compounds according to the optimised SPME conditions indicated that the SPME procedure was applicable for the analysis of the degraded citral products in headspace volatile of emulsion.     

Effect of Arabic gum,xanthan gum and orange oil on flavor release from diluted orange beverage emulsion

The influence of main emulsion components namely Arabic gum (13–20% w/w), xanthan gum (0.3–0.20% w/w) and orange oil (10–14% w/w) on semi-quantitative headspace analysis of target volatile flavor compounds released from a model orange beverage (diluted orange beverage emulsion) was evaluated by using a three-factor circumscribed central composite design (CCCD). For optimization procedure, the peak area of 13 volatile flavor compounds (i.e. ethyl acetate, α-pinene, ethyl butyrate, β-pinene, 3-carene, myrcene, limonene, γ-terpinene, octanal, decanal, linalool, neral and geranial) were considered as response variables. The response surface analysis exhibited that the significant (p < 0.05) second-order polynomial regression equations were successfully fitted for all response variables except for ethyl butyrate. A satisfactory coefficient of determination (R²) ranged from 0.831 to 0.969 (>0.8) was obtained for the response variables studied. No significant (p > 0.05) lack of fit was indicated for the reduced models except for the models fitted for limonene and linalool. This observation confirmed an accurate fitness of the reduced response surface models to the experimental data. The multiple response optimizations indicated that an orange beverage emulsion containing 15.87% (w/w) Arabic gum, 0.5% (w/w) xanthan gum and 10% (w/w) orange oil was predicted to provide the minimum overall flavor release.     

Identification of volatile compounds in soymilk using solid-phase microextraction-gas chromatography

Headspace solid-phase microextraction (HS-SPME) gas chromatography was used to analyze volatile compounds in soymilk. The effect of incubation temperature (30–70 °C) and time (5–60 min), sample volume (0.5–5 ml), and type of SPME fiber (65 μm CWAX–DVB, 70 μm PDMS–DVB and 85 μm CAR–PDMS) were studied. All the factors markedly affected sensitivity and selectivity. Among the three fibers tested, the CAR–PDMS fiber had greater sensitivity to a more diverse range of volatile compounds, followed by PDMS–DVB and CWAX–DVB fibers using both soymilk and water with added volatiles as a matrix. SPME optimization conducted using a water matrix with added known soy volatiles, showed the following conditions to be optimal for selectivity and sensitivity: incubation temperature of 40 °C, incubation time of 20 min, and sample volume of 5 ml (for volatile compound concentration of ∼25 ppm). The selected conditions were used for the analysis of volatiles in six commercial soymilk samples. A total of 30 volatile compounds were identified. The results showed significant differences in the total volatiles of the soymilk products. The repeatability of measurements of total volatiles compounds of soymilk was ∼5.4% for four replicate analyses. Similar volatile compounds were present in all the samples analyzed but at different concentrations. The method proposed is simple and can be used to measure both hexanal and/or total volatiles in soymilk samples.     

Influence of the type of fiber coating and extraction time on foal dry-cured loin volatile compounds extracted by solid-phase microextraction (SPME)

Extraction of dry-cured loin volatile compounds by solid-phase microextraction (SPME) was optimized. Two different fiber coatings: carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and three extraction times (15, 30 and 45 min) were assayed. Between the fibers tested, CAR/PDMS coated fibers extracted between two and three times more total amount of volatile compounds than the DVD/CAR/PDMS coating (1314 × 10⁶ vs. 526 × 10⁶ area units). Fifty five compounds were extracted by the CAR/PDMS fiber, while only 48 of these were found with the DVB/CAR/PDMS fiber. On the other hand, 6 additional volatile compounds were extracted by the CAR/PDMS coating, all of them being of low molecular weight. Three of the major compounds extracted, hexanoic acid, methyl ester; butanoic acid, 3-methyl-, methyl ester and hexanal, were found in high proportion in both fiber coatings. The effect of exposure time was more marked for the DVD/CAR/PDMS fiber than for the CAR/PDMS coating. Fifteen minutes of extraction provided a volatile compounds profile with lower area counts for most compounds and significantly different to that obtained with 30 and 45 min of extraction. The extraction yields of dry-cured loin volatile compounds varied according to the fiber coating used and the time of exposure. Therefore, extraction conditions should be selected depending on the objective of the study. Finally, it can be concluded that both porous fibers tested, CAR/PDMS and DVB/CAR/PDMS, provide a similar volatile compounds profile for dry-cured foal loin.     

基于HS-SPME-GC-MS和PCA的不同萃取头对鸡肉香精香气成分萃取效果比较

为提高鸡肉香精香气成分分析的可靠性,比较不同纤维涂层萃取头萃取鸡肉香精香气成分的效果,采用顶空固相微萃取(headspace solid-phase micro-extraction,HS-SPME)结合气相色谱质谱联用仪(gas chromatography-mass spectrometry,GC-MS)检测技术对热反应鸡肉香精中的挥发性风味物质种类和组成进行提取分析,通过灵敏性及主成分分析(principal component analysis,PCA)法比较香气成分数量及含量建立香气品质评价模型,研究不同纤维涂层萃取头(75μm CAR/PDMS、65μm DVB/PDMS、85μm PA、50/30μm DVB/CAR/PDMS)与所萃取挥发性物质间的相关性。结果表明,75μm CAR/PDMS萃取头为萃取鸡肉香精样品挥发性物质的最优萃取头,萃取得到样品中共含有146种挥发性物质,包括醇类24种(16.44%)、醛类16种(10.96%)、吡嗪类12种(8.22%)、呋喃(酮)类13种(8.91%),含硫化合物10种(6.85%)等多种香气物质,检测到2-甲基-3-呋喃硫醇、2-甲基-3-戊烷硫醇、(E,E)-2,4-癸二烯醛、(E,E)-2,4-庚二烯醛及反式-2-壬烯醛等关键肉香味化合物。     

Analysis of human male armpit sweat after fenugreek ingestion: Instrumental and sensory optimisation of the extraction method

In this study, we intend to develop a simple and selective procedure to extract compounds involved in the strong odour which appears after fenugreek ingestion (this odour is responsible of the so-called pseudo-maple syrup urine disease). Two procedures, solvent extraction and headspace solid-phase microextraction (HS-SPME), were employed to extract compounds from armpits sweat samples collected from two volunteer subjects. The HS-SPME extraction parameters were first optimised and then applied to extracts of armpit sweat collected from subjects after fenugreek ingestion. The sensory evaluation of the different extracts was carried by eight trained assessors; the HS-SPME and solvent extracts were, respectively, smelled by direct gas chromatography–olfactometry and direct olfaction. The results of sensory evaluation indicate that HS-SPME with a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre, of 50/30 μm film thickness and 2 cm length, gives a global odour close to that of sweat after ingestion of fenugreek infusion.     

Volatile Constituents of Jambolan (<Emphasis Type="Italic">Syzygium cumini</Emphasis> L.) Fruits at Three Maturation Stages and Optimization of HS-SPME GC-MS Method Using a Central Composite Design

The volatile compounds of jambolan (Syzygium cumini L.) fruit were determined at three different maturity stages (unripe, half-ripe, and ripe) by headspace solid-phase microextraction (HS-SPME)–gas chromatography-mass spectrometry (GC-MS) technique using five different fibers (Fused silica PDMS/DVB, DVB/CAR/PDMS, PEG, Stable flex PDMS/DVB, and PDMS). The optimal extraction conditions were evaluated using different variables such as adsorption temperature (minimum 25 °C, maximum 55 °C), salt quantity (minimum 0, maximum 30.0%), and extraction time (min 10, max 30 min). The major classes of compounds identified were ester, terpene, alcohol, aldehyde, and carboxylic acid. Ninety volatile compounds with characteristics aroma attributes were identified, and the primary compounds linked with development of characteristics aroma of ripe jambolan fruit pulp were trans-β-ocimene, β-ocimene, caryophyllene, humulene, D-α-pinene, L-β-pinene, β-pinene, D-limonene, α-terpineol, neo-allo-ocimene, 2-hexenal (E), δ-cadinene, 3-hexen-1-ol, (Z) β-linalool, terpinolene, eremophilene, valencene, 1-hexanol, longipinene, γ-terpinene, γ-muurolene, endo-borneol, o-cymene, nonanal, terpinen-4-ol, β-terpineol, α-muurolene, fenchol, α-fenchene, β-thujene, benzaldehyde, (E)-2-hexenal, β-cadinene, and decanal.     

Analysis of volatile compounds of Antrodia camphorata in submerged culture using headspace solid-phase microextraction

In this work a headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) and GC–olfactometry (GC–O) was developed to evaluate the profile of the volatile compounds that contribute to the aroma of Antrodia camphorata in submerged culture. For this purpose, the HS-SPME sampling method for the volatile compounds of A. camphorata in submerged culture was optimised by a D-optimal design. A HS extraction of the culture broth of A. camphorata followed by incubation on a carboxen/polydimethylsiloxane (CAR/PDMS) fibre during 31.8 min at 54.6 °C gave the most effective and accurate extraction of the volatile compounds. By the optimised method, a total of 49 volatile compounds were identified in culture broth of A. camphorata, while a total of 55 volatile compounds were identified in the mycelia. A series of C₈ aliphatic compounds (mushroom-like odour), several lactones (fruity odour) and l-linalool (citrus-like odour) were the most potent key odourant in both the mycelia and culture broth. This combined technique is fast, simple, sensitive, inexpensive and useful to monitor volatile compounds associated to A. camphorata.     

Optimization of equilibrium headspace analysis of volatile flavor compounds of malaysian soursop (Annona muricata): Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS)

Headspace solid-phase microextraction (HS-SPME) coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was applied for equilibrium headspace analysis of Malaysian soursop (Annona muricata) volatile flavor compounds. A two-level fractional factorial design (2^5-1) was used to determine the effect of SPME variables, namely, SPME fibers, adsorption temperature, extraction time, amount of salt, sample amount and sample concentration on the extraction efficiency of volatile flavor compounds. A total of 37 volatile compounds were identified, comprising 21 esters, 6 alcohols, 3 terpenes, 2 acids, 2 ketones, 2 aldehydes and an aromatic with different hydrophobicities (log P) ranging between −0.14 and 4.83. Extraction using 10 g of diluted (5% w/w) blended soursop pulp with CAR/PDMS fiber at 25 °C for 30 min and 30% (w/w) of NaCl under stirring mode resulted in the highest extraction efficiency of volatile flavor compounds. The principal component analysis score discriminated the influence of SPME variables on the equilibrium headspace concentration of target volatile compounds.     

A headspace solid-phase microextraction method development and its application in the determination of volatiles in honeys by gas chromatography

The first part of the paper presents the detailed optimisation of all steps of the determination procedure of volatiles from Polish honeys by headspace solid-phase microextraction (HS-SPME) as the sample preparation method and gas chromatography/mass spectrometry (GC–MS) as the method of final determination. In the result, the following conditions were applied: CAR/PDMS/DVB SPME fibre, the sample composition (5:1 w/w honey to water ratio), 3 g sample size. The other procedure parameters, like the temperatures of individual stages of the process, were also included.     

Using headspace solid phase micro-extraction for analysis of aromatic compounds during alcoholic fermentation of red wine

Timely monitoring of changes in the type and quantity of aromatic compounds throughout the must fermentation process provides useful information for wine makers. This paper aimed to use headspace solid phase micro-extraction coupled with gas chromatography (HS-SPME/GC–MS) to analyse aromatic compounds produced during must alcoholic fermentation. The results showed that both qualitatively and quantitatively, the PDMS/CAR/DVB fibre was suitable for extracting aromatic compounds in wine. The amount of alcohols, esters, acids and monoterpenes absorbed on the SPME fibre were influenced by the ethanol content. Calibration curves with a high correlation (R² > 0.900) obtained in seven ethanol contents (2%, 4%, 6%, 8%, 10%, 12% and 14%) were established to quantitatively determine the amount of aromatic compounds during alcoholic fermentation. A validated HS-SPME method for determining aromatic compounds was used to monitor aromatic compounds during Syrah alcoholic fermentation. This modified HS-SPME method was proved to be useful for controlling the oenological process.     

顶空固相微萃取- 气质联用法测定哈尔滨红肠的挥发性风味物质

为进一步探明烟熏灌肠类食品的风味特征,以哈尔滨红肠为对象,采用顶空固相微萃取制备样品,联合气质联用测定其主要挥发性物质。通过比较不同萃取头、萃取温度以及萃取时间对萃取效果的影响,获得较适的萃取条件：50/30μm DVB/CAR/PDMS萃取头、萃取温度50℃、萃取时间50min。采用气质联用对解吸物进行测定的结果表明,其挥发性风味物质的主要成分中醛类占17.59%、酮类占7.01%、酚类占7.27%、醇类占12.29%、烯萜类占9.39%、烷烃类占6.14%、含硫化合物占27.38%、杂环化合物占7.01%。     

欧姆加热对豆浆风味物质的影响

为研究欧姆加热对豆浆挥发性物质的影响,采用顶空固相微萃取结合气相色谱-质谱联用技术,对豆浆的风味物质进行分析,利用内标法对各风味物质成分定量分析。通过对比50/30?μm二乙基苯/碳分子筛/聚二甲基硅氧烷（divinylbenzene/carboxen/polydimethylsiloxane,DVB/CAR/PDMS）、100?μm PDMS、65?μm PDMS/DVB 3 种萃取头对豆浆风味物质的萃取效果,筛选出最佳的萃取头,并在最适条件下分析豆浆的风味物质成分,为排除热效应对实验结果的影响,2?种热处理历程尽可能保持一致。结果表明：65?μm PDMS/DVB纤维萃取头较100?μm PDMS和50/30?μm DVB/CAR/PDMS纤维萃取头更适宜豆浆风味物质的测定;从豆浆样品中共检测到35?种挥发性物质,其中醛类物质16?种,醇类物质5?种,酮类物质3?种,酯类物质1?种,杂环烃类物质10?种,主要包括己醛、（E）-2-庚烯醛、1-辛烯-3-醇等,这些物质共同组成豆浆的特征香气;不同加热处理对豆浆风味物质种类的影响不大,但是对特征香气含量有显著影响（P＜0.05）;欧姆加热处理组样品中己醛、1-辛烯-3-醇、（E）-2-辛烯醛的含量分别比传统加热处理组约低45.55%、58.60%、25.56%,且在欧姆加热处理样品组中未检测到（E）-2-己烯醛和正己醇,而这些物质是豆腥味的主要组成成分。因此,利用欧姆加热方式加热豆浆可以显著降低豆浆的豆腥味。本研究可以为欧姆加热技术在豆浆加工业中的应用提供理论依据。     

Identification of volatile flavor compounds in Chinese Sinkiang camel-naizi using different solid phase microextraction fibers

Volatile components of Chinese Sinkiang camel-naizi (CSCN) were analyzed using solid phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS). A total of 45 volatile compounds were identified by using 3 fibers, including 17 alcohols, 4 aldehydes, 13 acids, 8 esters, 1 sulfur-containing compound, 1 lactone, and 1 ketone. Among all the compounds identified, various alcoholic compounds accounted for 78.91% of the total volatiles, and the amount of various esters was only next to that of alcohols, which accounted for 15.01% of the total volatiles. The content of acids, lactone, aldehydes, ketone, and sulfur-containing compound accounted for 6.08%. All of these volatiles constituted the characteristic flavor of raisin-like, fruity, sweet, cheesy, and yogurt-like note of CSCN. The extraction performances of 3 types of SPME fibers (75 μm CAR/PDMS, 65 μm PDMS/DVB, and 50/30 μm DVB/CAR/PDMS) were compared in this study. Of the 3 fibers, the DVB/CAR/PDMS fiber extracted the most volatiles, and the CAR/PDMS fiber the least. The DVB/CAR/PDMS fiber showed the best performance in trapping compounds of CSCN with different polarities.     

Identification of volatile components in Chinese Sinkiang fermented camel milk using SAFE,SDE, and HS-SPME-GC/MS

The volatile components of Chinese Sinkiang fermented camel milk were isolated by solvent assisted flavour evaporation (SAFE), simultaneous distillation extraction (SDE, dichloromethane and diethyl ether as solvent, respectively) and headspace solid-phase microextraction (HS-SPME, CAR/PDMS, PDMS/DVB and DVB/CAR/PDMS fibre extraction, respectively) and analysed by GC/MS. A total of 133 volatile components were identified under 6 different conditions, including 30 esters, 20 acids, 18 saturated alcohols, 15 unsaturated aliphatic alcohols, 8 saturated ketones, 9 saturated aldehydes, 8 unsaturated aliphatic aldehydes, 6 furans, 5 sulphur-containing compounds, 5 ethers, 5 lactones, 3 other compounds, and 1 unsaturated aliphatic ketone. Three pretreatment methods were compared, assisted by principal component analysis (PCA). The results indicated that the volatile components obtained using different methods varied greatly both in categories and in content, and therefore, a multi-pretreatment method should be adopted together with GC/MS. A total of 71 aroma-active compounds were detected by gas chromatography-olfactometry (GC–O), among which 66 aroma-active compounds were found by SDE (60, dichloromethane as solvent; 24, diethyl ether as solvent), 26 by SAFE.     

Response surface methodology and multivariate analysis of equilibrium headspace concentration of orange beverage emulsion as function of emulsion composition and structure

The influence of emulsion composition (i.e. Arabic gum, xanthan gum and, orange oil) and structural emulsion properties (i.e. average droplet size and apparent viscosity) on equilibrium headspace concentration of beverage emulsions was investigated. Increase in average droplet size led to increase the equilibrium headspace concentration of more hydrophilic volatile compounds (i.e. lower log P) such as ethyl acetate and octanal, but decrease in more hydrophobic volatile compounds such as 3-carene, myrcene and limonene. In most cases, apparent viscosity had significant positive effect on equilibrium headspace concentration. Principle component analysis (PCA) score discriminated the beverage emulsions containing the same orange oil content but different contents of emulsifiers in different classes, thus indicating the significant (p < 0.05) effect of emulsifier fraction on equilibrium headspace concentration. Beverage emulsion containing 22.2% (w/w) Arabic gum, 0.52% (w/w) xanthan gum and 14.21% (w/w) orange oil was estimated to provide the highest equilibrium headspace concentration.     

Optimisation of HS-SPME to study representativeness of partially baked bread odorant extracts

Head-space solid phase microextraction (HS-SPME) has been successfully applied to extract partially baked bread volatile compounds. During this study, three HS-SPME parameters (extraction time, extraction temperature, SPME fibre) were optimised on volatile compounds extraction thanks to a representativeness analysis. Results displayed that a CAR/PDMS or a CAR/PDMS/DVB fibre associated with a time of 30 min or 60 min and a temperature of 35 °C allowed obtaining odorant extracts representative of the bread odour. A flash profile was then carried out to highlight the different flavour perceptions which could exist between these four extracts even if they were close to the same bread odour. Completed by the analysis of their qualitative composition, the study revealed that there were some analytical differences in odour perceptions. These differences may be linked to synergic effects caused by the presence of characteristic volatile compounds in the extracts.     

Characterising the release of flavour compounds from chewing gum through HS-SPME analysis and mathematical modelling

The headspace solid-phase microextraction (HS-SPME) technique combined with GC–MS was evaluated to study 33 selected flavour compounds released from chewing gum. The operating conditions of SPME were optimised, including different fibres (PDMS, DVB/CAR/PDMS, PA and PDMS/DVB), sample size, extraction time and temperature. The results indicated that while HS-SPME was a rapid and valuable technique, poor reproducibility occurred under all conditions. It was found that this deficiency could be alleviated by utilising mathematical modelling techniques, an approach which had not been previously used in the analysis of flavour compounds in chewing gum by HS-SPME. Compared to the instrumental analysis data themselves, the models provided more insights to the release behaviour of flavour compounds from chewing gum and the more reproducible kinetic rate constants might be used for comparing the release of different compounds or the same compound under different conditions.     

固相微萃取结合气质联用法分析一种奶味香精中的挥发性成分

应用固相微萃取法采用3种不同萃取纤维,结合气相色谱-质谱联用技术,剖析1种国外奶味香精样品中的挥发性成分。结果表明;以Carboxen/聚二甲基硅氧烷(carboxen/polydimethylsiloxane,CAR/PDMS)为萃取纤维的方法鉴定出39种挥发性成分,以聚二甲基硅氧烷/二乙烯基苯(polydimethylsiloxane/divinylbenzene,PDMS/DVB)为萃取纤维的方法鉴定出41种挥发性成分,以二乙烯基苯/Carboxen/聚二甲基硅氧烷(Divinylbenzene/Carboxen/Polydimethylsiloxane,CAR/PDMS/DVB)为萃取纤维的方法鉴定出40种挥发性成分;3种纤维萃取的分析结果相互补充,共鉴定出51种挥发性成分,其中酯类、醛酮类和内酯类化合物的含量最高,分别为26.12%、25.95%和15.16%,是该种奶味香精的主要组成成分。