Screening of musty-earthy compounds from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry

Compounds responsible for musty-earthy off-flavours in cork, namely 2-methylisoborneol (MIB), geosmin (GSM), 2,4,6-trichloroanisole (TCA) and 2-methoxy-3-isopropylpyrazine (IPMP), were determined from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME–GC–MS). The influence of the fibre coating used and of the extraction time and temperature were investigated for the joint analysis of MIB, GSM, TCA and IPMP. Considering the obtained results, an extraction time of 30 min at a temperature of 50 °C were fixed as experimental conditions, using a divinylbenzene/carboxen-polydimethylsiloxane/polydimethylsiloxane (DVB/CAR/PDMS) fibre. Quality parameters of the chromatographic method were obtained and good recoveries (117–128%) were found in spiked aqueous cork macerates. Using the same experimental conditions, the presence of guaiacol, 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA) and 2-methoxy-3,5-dimethylpyrazine (MDMP) could also be evaluated in a single chromatogram. From all the compounds analyzed in tainted samples, TCA and guaiacol were the only contaminants present and only TCA concentrations were found above its perception threshold in water.     

Differentiation of “Claret”, Rosé, Red and Blend wines based on the content of volatile compounds by headspace solid-phase microextraction and gas chromatography

We studied 46 samples of wine from Denomination of Origin of La Rioja: 8 rosé, 8 “claret”, 10 red, 10 artificial blend and 10 ungrouped wines (3 rosé, 2 “claret”, 2 red and 3 blend). The samples were analysed by gas chromatography using headspace-solid-phase microextraction (HS-SPME) with a Carbowax-divinylbenzene (CW/DVB) fibre. The variables considered were 3-methyl butyl acetate, 3-methyl-1-butanol, ethyl hexanoate, 1-hexanol, ethyl octanoate, diethyl succinate, hexanoic acid, 2-phenylethanol, octanoic acid, decanoic acid and geraniol, all significant for distinguishing the types of wines except 3 metil-1-butanol and 1-hexanol. The different wine samples were classified by multivariate statistical methods. Good differentiation between the different groups of samples was achieved by means of principal component analysis and hierarchical cluster analysis. Linear discriminant analysis was used to differentiate and classify these wines. 3-methyl-butyl acetate, ethyl octanoate, diethyl succinate, hexanoic acid, 2-phenylethanol and decanoic acid were the most discriminant variables and gave 100% recognition ability and 100% prediction ability.     

固相微萃取结合气相色谱-质谱测定海南番木瓜香气成分

运用顶空固相微萃取结合气相色谱-质谱联用技术分析番木瓜香气成分,考察萃取头类型、萃取时间、样品量和氯化钠添加量4个单因素对萃取成分的影响。结果表明最佳萃取条件为萃取头:50/30μm DVB/CAR/PDMS;样品量:6g番木瓜浆液;氯化钠添加量:3g;萃取时间:30min。将此条件下所得谱图与标准谱图比对分析,共鉴定出28种化合物,占总峰面积的90.82%,番木瓜主要香气化合物为甲苯（36.68%）、芳樟醇（33.55%）、异硫氰酸苄酯（7.04%）、顺式芳樟醇氧化物（2.56%）和氧化芳樟醇（1.46%）。      

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.     

Solid-phase microextraction for headspace analysis of key volatile compounds in orange beverage emulsion

Headspace solid-phase microextraction (HS-SPME) gas chromatography was used to analyze target flavor compounds in orange beverage emulsion. The effects of SPME fiber (PDMS 100 μm, CAR/PDMS 75 μm, PDMS/DVB 65 μm and DVB/CAR/PDMS 50/30 μm), adsorption temperature (25–45 °C), adsorption time (5–25 min), sample concentration (1–100%), sample amount (5–12.5 g), pH (2.5–9.5), salt type (K₂CO₃, Na₂CO₃, NaCl and Na₂SO₄), salt amounts (0–30%) and stirring mode were studied to develop HS-SPME condition for obtaining the highest extraction efficiency and aroma recovery. For the head space volatile extraction, the optimum conditions were: CAR/PDMS fiber, adsorption at 45 °C for 15 min, 5 g of diluted beverage emulsion (1:100), 15% (w/w) of NaCl with stirring and original pH 4. The main volatile flavor compounds were: limonene, 94.9%; myrcene, 1.2%; ethyl butyrate, 1.1%; γ-terpinene, 0.41%; linalool, 0.36%; 3-carene, 0.16%; decanal, 0.12%; ethyl acetate, 0.1%; 1-octanol, 0.06%; geranial, 0.05%; β-pinene, 0.04%; octanal, 0.03%; α-pinene, 0.03%; and neral, 0.03%. The linearity was very good in the considered concentration ranges (R² ? 0.97). Average recoveries ranged from 88.3% to 121.7% and showed good accuracy for the proposed analytical method. Average relative standard deviation (RSD) for five replicate analyses was found to be less than 14%. The limit of detection (LOD) ranged from 0.06 to 2.27 mg/l for all volatile flavor compounds and confirmed the feasibility of the HS-SPME technique for headspace analysis of orange beverage emulsion. The method was successfully applied for headspace analysis of five commercial orange beverage emulsions.     

Discrimination of Chinese vinegars based on headspace solid-phase microextraction-gas chromatography mass spectrometry of volatile compounds and multivariate analysis

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography mass spectrometry (GC-MS) was applied for the determination of the characteristic volatile profiles of Chinese vinegars. Multivariate statistical techniques, such as principal component analysis (PCA) and cluster analysis (CA), were used to characterize the different Chinese vinegars by types, fermentation method, and production area. A total of 56 volatile compounds were identified, including 15 esters, 10 aldehydes, 5 acids, 12 alcohols, 5 ketones, 4 volatile phenols, 2 pyrazines, and 3 miscellaneous compounds. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. The PCA results showed that characterizing the Chinese vinegars by HS-SPME-GC-MS was highly related to their type, fermentation method, and production area, and all these influencing factors were not independent. The CA results indicated that the fermentation method had a greater effect than vinegar type and production area. The results showed that HS-SPME-GC-MS together with chemometrics could provide practical reference for characterization of Chinese vinegars. Practical Application: HS-SPME coupled with GC-MS was applied for the determination of the characteristic volatile profiles of Chinese vinegars. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. HS-SPME-GC-MS together with chemometrics was an efficient tool for evaluating vinegar authenticity.     

Analysis of volatile flavour components by dynamic headspace analysis/gas chromatography-mass spectrometry in roasted pistachio extracts using supercritical carbon dioxide extraction and sensory analysis

In this study, optimum process parameters for supercritical carbon dioxide (CO₂) (SC-CO₂) extraction of roasted pistachio (Pistacia vera L.) were investigated by depending on amount of the characteristic flavouring components (α-pinene, limonene-D, α-terpinolene and β-myrcene). The extracts were analysed by DHA/GC-MS for determination of the volatile compounds and the optimum process parameters were decided as 200 g, 350 Bar, 70°C, 75 g _CO2/min and 60 min. In the pistachio extracts obtained having the optimum process parameters, α-pinene, β-myrcene, limonene-D and α-terpinolene were detected as 24.47 g/100 g, 0.52 g/100 g, 2.25 g/100 g and 5.70 g/100 g among 31 volatile compounds in total, respectively. The fatty acid composition of the extract, which had the most desirable taste and flavour, was detected by gas chromatography using fatty acid methyl esters (FAME) preparation. The fatty acid composition analysis showed that the pistachio extract had included mostly oleic acid (67.51%, w/w) and linoleic acid (17.85%, w/w).     

Botanical discrimination and classification of honey samples applying gas chromatography/mass spectrometry fingerprinting of headspace volatile compounds

A validated method for the discrimination and classification of honey samples performing GC/MS fingerprinting of headspace volatile compounds was developed. Combined mass spectra of honey samples originated from different plants and geographical regions of Greece were subjected to orthogonal partial least squares-discriminant analysis™ (OPLS™-DA), soft independent modelling of class analogy (SIMCA), and OPLS™-hierarchical cluster analysis (OPLS™-HCA). Analyses revealed an excellent separation between honey samples according to their botanical origin with the percentage of misclassification to be as low as 1.3% applying OPLS™-HCA. Fragments (m/z) responsible for the observed separation were assigned to phenolic, terpenoid, and aliphatic compounds present in the headspace of unifloral honeys. On the other hand, a variable classification for citrus and thyme honeys according to their geographical origin could be achieved. Results suggested that the developed methodology is robust and reliable for the botanical classification of honey samples, and the study of differences in their chemical composition.     

Components detected by means of solid-phase microextraction and gas chromatography/mass spectrometry in the headspace of artisan fresh goat cheese smoked by traditional methods

The study of the headspace components of fresh smoked goat cheese, was carried out by means of solid-phase microextraction using a polyacrylate fiber followed by gas chromatography/mass spectrometry. The samples studied were six artisan Palmero cheeses manufactured following traditional methods and smoked using pine needles. The cheese regions studied were exterior, interior, and a cross section. In total, more than 320 components were detected, the exterior region being the richest in components, among which were acids, alcohols, esters, hydrocarbons, aldehydes, ketones, furan and pyran derivatives, terpenes and sesquiterpenes, nitrogen derivatives, phenol, guaiacol and syringol derivatives, ethers, and others. In addition to typical cheese components, typical smoke components were also detected; these latter were present especially in the headspace of the exterior region and only those in significant concentrations in the exterior region were also detected in the interior. The main components were acids and phenolic derivatives. These latter compounds play an important role in the flavor of this cheese, and their relative proportions together with the presence of specific smoke components derived from pine leaves may be considered of interest in order to distinguish this cheese from others smoked with different vegetable matter.     

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.     

Determination of volatile compounds to characterize fish spoilage using headspace/mass spectrometry and solid‐phase microextraction/gas chromatography/mass spectrometry

Changes in volatile compounds were monitored in whiting (Merlangius merlangus), cod (Gadus morhua) and mackerel (Scomber scombrus) and related to spoilage. Data are presented from headspace/mass spectrometric (HS/MS) analysis and solid‐phase microextraction/gas chromatographic/mass spectrometric (SPME/GC/MS) analysis at two time points (day 0 and day 10) during storage at 4 °C. HS/MS revealed 24 ions that could be used as markers of spoilage. SPME/GC/MS identified 86 compounds, 20 of which could perhaps be used to characterize freshness: principally alcohols, ketones, aldehydes and C₂–C₁₁ esters. Compounds common to the three species studied appear to be generated by microbial degradation. Copyright © 2005 Society of Chemical Industry     

Screening and distinction of coffee brews based on headspace solid phase microextraction/gas chromatography/principal component analysis

The volatile profiles of espresso and plunger (cafetière) coffees prepared from (1) an 80:20 (w/w) blend of natural roasted Robusta and Arabica (Robusta Natural blend), (2) a 40:40:20 (w/w/w) blend of Robusta Natural blend, Robusta torrefacto roast (850 g kg^?1 Robusta, 150 g kg^?1 sugar) and (3) natural roasted pure Arabica were established by headspace solid phase microextraction (SPME) after selection of the fibre coating (polyacrylate or polydimethylsiloxane) and the temperature and time of extraction. For the analysis of furans and indoles the polyacrylate coating proved to be more suitable; however, for the overall characterisation of the volatile composition of espresso and plunger coffees the polydimethylsiloxane coating was chosen. SPME/gas chromatography (GC)/mass spectrometry (MS) analyses allowed the identification of 37 compounds: four aldehydes, two ketones, 11 furans, 10 pyrazines, two pyridines, three phenolic compounds, two indoles, one lactone, one ester and one benzothiazine. The volatile composition was related more to the botanical variety (Arabica or Robusta) than to the method of preparation of the brew (espresso or plunger). Furthermore, use of the variability provided solely by the GC peak areas and respective retention times, combined with principal component analysis (PCA), yielded the information necessary for discrimination. The combined technique of headspace SPME/GC/PCA, as an alternative to conventional techniques based on GC/MS, is proposed as a lower‐cost, fast and reliable technique for the screening and distinction of coffee brews. Copyright © 2003 Society of Chemical Industry     

Aroma analysis of apple juice: Influence of salt addition on headspace volatile composition as measured by gas chromatography and corresponding sensory evaluations

Sensory response to the aroma of a food depends on the composition and concentrations of the volatiles of the headspace. When analyzing the headspace composition by gas chromatography, salts are often added to the sample as a means of increasing the concentration of the aroma compounds in the vapor phase (e.g. enrichment of the vapor phase). This will only give a correct impression of the original aroma when all volatile components are affected equally. In this study on apple juice aroma, it is demonstrated that the degree of headspace enrichment resulting from salt addition is different for esters, aldehydes and alcohols, In our collection system, the average degree of enrichment at 40°C (described in terms of Relative Peak Areas—RPA) was greater than 4 for alcohols, between 1·75 and 3·50 for aldehydes and less than 1·75 for esters. How these differences can be useful when trying to identify gas chromatography peaks is also discussed.Sensory evaluations showed that aroma response is changed when salt is added to the juice, resulting in an increased aroma intensity and off-aroma. Fruit aroma was not affected. A comparison of the sensory responses with headspace gas chromatographic measurements indicates that increase in off-aroma can be related to the increase in alcohol percentage in the headspace.From these results it can be noted that, when attempting to correlate sensory scores with aroma component concentrations as measured by headspace gas chromatography, it is most important that the test conditions utilized for each analysis correspond as closely as possible with each other.     

Evaluation of chemical indicators for monitoring freshness of food and determination of volatile amines in fish by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A headspace solid-phase microextraction and gas chromatography–mass spectrometric (HS-SPME-GC-MS) method was developed to monitor methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA) in fish. The alkylamines were extracted using carboxen/divinylbenzene/polydimethylsiloxane (CAR/DVB/ PDMS) fibres at 25 °C and exposure time of 5 min. Calibration curves showed good linearity in the concentration range of 0.5–10 μg ml⁻¹ and the corresponding coefficients of correlation were all above 0.99. Detection limits were estimated to be 0.10 μg ml⁻¹ for MA and DMA; and 0.15 μg ml⁻¹ for TMA. Intra-day and inter-day variation of spike samples at 2.0 μg g⁻¹ were 4.3–6.2% and 5.4–10%, respectively. Recovery of the method for TMA was found to be comparable to that of a standard titration method with the mean deviation of the two methods being 6.7%. The validated method was applied to study the decay profiles of the concerned alkylamines in two fish species that were stored at 0 and −20 °C; and the results obtained were compared with that obtained by using the classical parameter of total volatile basic nitrogen (TVBN).     

Assessment of the effect of the non-volatile wine matrix on the volatility of typical wine aroma compounds by headspace solid phase microextraction/gas chromatography analysis

BACKGROUND: The aim of this study was to evaluate the effect of the whole non‐volatile wine matrix composition on the volatility of typical wine aroma compounds by comparing the slopes of regression lines of five deodorised and reconstituted wines with the slopes calculated for the same compounds in a control wine with no matrix effect. RESULTS: The main effect observed was a reduction in the slopes, or a retention effect, that was largest for the reconstituted sparkling wine, which showed between 11 and 69% lower slopes than the control wine. In addition, an increase in the slopes, or a ‘salting‐out’ effect, in the most compositionally complex reconstituted aged‐red and sweet wines was also noticed for some volatiles with a very low boiling point or a low hydrophobic constant value. CONCLUSION: This study has shown that the non‐volatile composition of wines strongly affects the volatility of wine aroma compounds. In addition, the aroma chemical class, in particular its physicochemical properties (volatility and hydrophobicity), strongly influences this behaviour. On the basis of these results, many odour threshold values calculated in simple hydroalcoholic solutions and usually employed to evaluate the odour importance of specific volatile compounds may have been over‐ or underestimated. Copyright © 2011 Society of Chemical Industry     

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.