Sampling Of Volatile Compounds Research Articles

Microwaves affect the formation of volatile compounds in peper powder by changing the nucleophilic addition reactions in Maillard reactions.

We explored the effect of microwave heating (MWH) and electric heating (ETH) on the volatile compounds (VCs) of pepper (Capsicum annuum L.). The spectral of the produced melanoidins by baking were used to screen samples with similar baking degrees. Mass spectrometry was used to detect the differences of VCs in samples. The results showed a dose-dependent effect between the intensity of absorption and fluorescence of melanoidins, which can be utilized as indicators for assessment baking degree. MWH samples produced larger variety of VCs than ETH. Changes in the variety and content of VCs infer changes in the flavor of pepper. According to the mechanism of Maillard reaction (MR) and MWH, it was deduced that MWH changes the type of chemical reaction in MR by affecting the distribution of valence electrons in the compounds. Therefore, MWH can be used as a novel method to modify the VCs and flavor of peppers.

Studies on the influence of natural resource utilization by humans on foraging behavior of honey bees at rural ecosystems.

Human utilization of natural resources acts as a main driver in altering the ecosystem service and functions. Apart from indirect influence, these human activities also tempt for the behavioral shift in insects especially in honey bees. The foraging behavior of honey bees from the natural floral resources to the man-made food sources eventually degrade the ecosystem's services and cause declining of the honey bee population. Understanding this foraging behavior of bees could help in opting for viable conservation measures for honey bees. In order to understand the influence of human utilization of natural resources on the foraging behavior of bees and its negative impacts on the bee population, the study was carried out in the sites where humans collect palm sap. Palm sap collectors used different containers (mud pots and pet bottles) to collect the palm sap from Borassus flabellifer. The number of containers per tree, volume of palm sap per container/tree, bee visiting frequency, and bee mortality per container/tree were measured at different ecosystems. Palm saps were collected freshly and volatile compounds of samples were identified using FT-IR and GC-MS analysis. The identified volatile compounds were used to study the interaction between volatile compounds and odorant-binding proteins (OBPs) of honey bees for understanding the foraging behavior of bees using in silico approach. Our results clearly showed that bee visitation frequency was directly correlated (0.94) with bee mortality in palm sap in different study sites. The average number of bee mortality was recorded as 491.2 ± 23.48 bees per container/tree/day. GC-MS analyses revealed the presence of 35 volatile compounds in collected palm sap from different study sites. Furthermore, molecular docking studies were performed for all 35 palm volatile compounds OBPs of honey bees to analyze their binding affinities. Docking studies showed that 1-methylbutylmandelate and 6-(hydroxymethyl)-1,4,4-trimethylbicyclo [3.1.0] hexan-2-ol have high binding affinity with OBP residues of bees. These volatile compounds might act as an attractant for bee populations for their foraging behavior. Based on this study, we conclude that human utilization of palm sap has created new ecological niches which highly alters the foraging behavior of bees and results in declining bee populations.

Impact of different FD-related drying methods on selected quality attributes and volatile compounds of rose flavored yogurt melts

Effects of three freeze drying methods including freeze-drying (FD), infrared pulse-spouted freeze-drying (IRPSFD), and microwave pulse-spouted freeze-drying (MPSFD) on physical properties (color, odor, texture, bulk density, and rehydration time), volatile compounds, bioactive compounds (total phenolics and anthocyanins), and antioxidant capacities of rose flavored yogurt melts are evaluated and discussed. FD samples possessed the shortest rehydration time (7.30 sec) and lowest bulk density (0.117 g/cm3). The color analysis showed the MPSFD sample was darker and had higher red coloration than FD and IRPSFD samples. From the PCA and LDA results, the odor of IRPSFD sample was closer to FD sample than MPSFD sample. FD and IRPSFD showed much better retention of volatile compounds in samples than MPSFD. Moreover, IRPSFD samples contributed better product quality over MPSFD and matched to FD samples. Results indicated that IRPSFD may provide an alternative technique for freeze dried rose flavored yogurt melts and many other foods with high-quality characteristics.

Analysis of Caffeine, Chlorogenic Acid, Trigonelline, and Volatile Compounds in Cold Brew Coffee Using High-Performance Liquid Chromatography and Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry.

This study investigated the non-volatile and volatile compounds in samples of cold brew (CB) coffee, coffee from a coffee shop (CS), ready-to-drink (RTD) coffee, and brewed coffee from a coffee maker (CM). The volatile compounds were identified using headspace solid-phase microextraction with gas chromatography-mass spectrometry, and the samples were treated with high-performance liquid chromatography for the quantification of caffeine, chlorogenic acid, and trigonelline. The results indicate that RTD coffee had the lowest amounts of non-volatile compounds. A total of 36 volatile compounds were semi-quantified; the contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples. The contents of 25 volatile compounds in the CM sample were higher than those in the CB sample. The consumer and instrumental data show that the bitterness intensity was correlated with pyrazines, pyrroles, and guaiacols, whereas the coffeeID intensity was correlated with phenols. Semi-quantification and principal component analysis results show that the extraction method and temperature could influence the volatile compound profiles.

Effects of roasting by charcoal, electric, microwave and superheated steam methods on (non)volatile compounds in oyster cuts of roasted lamb

This work was conducted to compare (non)volatile compounds and sensory evaluation of oyster cuts of roasted lamb. Three newer roasting methods, namely electrically heated air (EHA), microwave heat (MWH) and superheated steam (SHS), were compared with traditional burning charcoal (BCC). The results showed that the 3 new roasting methods all generated rich nonvolatile compounds and volatile compounds in samples, which was similar to the results of those prepared by BCC. Particularly, the EHA produced more nonvolatile compounds and higher equivalent umami concentrations than the other new methods, especially regarding umami amino acids. Moreover, the EHA and SHS methods had better sensory evaluations than the MWH, including acceptability, fat and roast flavours, and they had better odour activity values (OAVs) of characteristic volatile compounds, such as octanal, nonanal and (E, E)-2,4-decadienal. It was concluded that the EHA might be a potential method to replace the BCC due to our findings about nonvolatile compounds, OAVs of volatile compounds and sensory evaluation

Direct Classification of Volatile Organic Compounds in Heat-Treated Glutathione-Enriched Yeast Extract by Headspace-Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS)

Yeast extract (YE) is tremendously used as a flavor enhancer in foods because of its composition. However, different types of YE have different aromatic profiles. This study focuses on the thermal treatment of glutathione-enriched yeast extract (GSH-YE) at different temperatures with the addition of Maillard precursors to investigate any change in its volatile organic profile. Headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) was utilized for the instrumental analysis. A total number of 104 volatile compounds were analyzed through this approach. Qualitative and quantitative analysis of the samples were made in order to calculate the concentration of volatile compounds in samples. Sensory evaluation was performed to compare the overall aroma descriptions with the volatile profile of the heat-treated samples. Sensory scores revealed that an increase in the thermal temperature significantly affected the meaty and roasted aroma of GSH-YE. Many sulfur-containing volatile compounds including 2-methyl-3-furanthiol, 2-furfurylthiol, 2-methyl-3-(methylthio)furan, dimethyl trisulfide, 2-acetylthiazol, and some furans and pyrazines related to meaty and roasted odor notes were reported in this study. Significant increase in the amounts of furfural and dimethyl sulfide was observed in samples having higher thermal temperatures as compared with the control treatment. The temperature of 100 °C with adequate amounts of Maillard precursors in GSH-YE was considered an optimal condition for generating ample amounts of 2-methyl-3-methylthiofuran and 2-furfurylthiol. The 3D graphical data confirms the potential application of HS-GC-IMS as a more potent instrumental approach in the determination of volatile compounds in yeast extract.

Olfactory Atlases with an Array of Porphyrinoids Coated ZnO Nanoparticle

Olfactory Atlases with an Array of Porphyrinoids Coated ZnO Nanoparticle

Determination of fatty acids profiles and volatile compounds of cows’ and goats’ butters

In this study, the fatty acid composition and volatile components of cows’ and goats’ yayik butters were analyzed. For this purpose, analyzes in cows’ and goats’ yayik butter obtained from local markets in Adıyaman province were performed. Saturated fatty acids (SFAs) were determined as dominant fatty acids in the butter samples. While the highest SFA content was detected in goats’ butters, the highest unsaturated fatty acid (UNSFA) and monounsaturated fatty acid (MUFA) contents were in cow samples. Furthermore, some individual fatty acid concentrations (tridecanoic, behenic and α-linolenic) of cows’ and goats’ butters were significantly different. Additionally, the total 27 volatile compounds including alcohols, aldehydes, acids, esters, hydrocarbons, ketones and terpenes were quantified in samples. The most important volatile compounds in samples were oxylene, mxylene, butyric, caprylic and valeric acids.

Statistical Analysis of GC/MS Data from Beef Steaks Cooked with Different Grill Temperatures and Steak Thicknesses Containing Missing Values, Lacking Normal Distributions, or Unequal Variance

ObjectivesOur objectives were to determine the degree of normality in selected volatile compound samples, the improvement to normality transformations may make, and the changes in interpretation transformations could induce.Materials and MethodsBeef strip loins (n = 32) were sliced 3.81 or 1.27 cm thick. Steaks were cooked on an electric flat grill set at either 176°C or 232°C to an internal cook temperature of 71°C. Cubes (1.27 square) were transferred to a 470 mL glass jar and the static headspace was collected with SPME for 2 h. The SPME was injected into a multi-dimensional GC/MS identification of volatile aroma compounds. Volatiles were selected with a MS quality score above 75 and occurred in a minimum of 10% of the total steak samples. Absence of an observation for a volatile compound may be due to treatment effect, instrumentation limits, or simply missing from the sample. To analyze the normality of volatiles, representative volatiles selected were benzaldehyde, methyl-pyrazine, nonenal, and 2-octanone, as they were present in 95, 63, 42, or 20% of the total steak samples, respectively. These selected volatiles were then subjected to square root, log10, or Box-Cox transformations. If a volatile was absent in a steak sample, that cell was designated as either a missing value (MV) or as a zero (0). Shapiro-Wilk, box-plot, and normality distribution plots were used to measure normality for each of the volatiles across all conditions. Brown-Forsythe and Bartlett’s tests were used to determine homogeneity of variance.ResultsVolatiles designated as a zero when no GC total ion counts (TIC) were present had residuals within treatment cells that were not normally distributed (P < 0.05). Volatile compounds nonenal and 2-octanone were normally distributed (P > 0.05) when empty cells were designated as MV, but benzaldehyde and methyl-pyrazine were not (P < 0.05). Square-root transformation of the data resulted in all the data designated with MV to be normally distributed (P > 0.05) while data with empty cells designated with 0 were unchanged and not normal (P < 0.05). Furthermore, Box-Cox transformations of MV data had lambda values of 0.23, 0.11, 0.18, and 0.10 for benzaldehyde, methyl pyrazine, nonenal, and 2-octanone, respectively. Brown-Forsythe and Bartlett’s test indicated that as the percentage of volatiles present decreased, the treatment mean responses became less homogeneous in their variance (P < 0.05) as indicated by the fact that only benzaldehyde upheld the assumption of homoscedastic behavior (P > 0.05).ConclusionAnalysis of volatile aroma compounds from cooked beef results in numerous missing values in the data, and by nature the data are not normally distributed, nor do they have homogenous variance as a result. Analyzing data with missing values rather than zeroes improves normality and additionally, transformation of the data using square root or Box-Cox significantly improved normality but had only minor impact on homogeneity of variance. ANOVA F-ratios were consistently highest on data that were entered with missing values rather than zeroes and were not transformed. Care should be taken analyzing volatile GC data to take into account the basic assumptions regarding the data and steps can be taken to conform to those assumptions.

Application of an electronic nose for determination of pre‐pressing treatment of rapeseed based on the analysis of volatile compounds contained in pressed oil

SummaryThe article presents an attempt to use an electronic nose together with a new three‐parameter method for generation of a digital smellprint in order to specify the mode of processing of rapeseed based on the analysis of volatile compounds contained in cold‐pressed rapeseed oil. Prior to the pressing process, the seeds were roasted or improperly stored to obtain oil samples with varied technological quality. The quality of pressed oils was evaluated by determination of the acid value. Furthermore, changes in oil colour were assessed with the use of an imaging colorimeter. Volatile compounds were determined with the use of gas chromatography and an electronic nose with a metal oxide semiconductor (MOS) sensor matrix. It was found that the mode of seed pre‐treatment before pressing did not change the colour of the oil significantly. However, it influenced the profile of volatile organic compounds and changed their proportions. Ketones represented the largest proportion of volatile compounds determined for roasted samples and those pressed from seeds moistened up to 25% (w.b.). Alcohols dominated in samples moistened up to 10 and 12%, terpenes were the dominant volatile compounds in samples roasted at 140 °C, and other volatile compounds dominated in samples moistened up to 10 and 20% (w.b.). In turn, esters and aromatic compounds accounted for the lowest proportion in the analysed samples. The results shown by the electronic nose were correlated with the presence of particular groups of volatile compounds in rapeseed oil.

Water stress and ripeness effects on the volatile composition of Cabernet Sauvignon wines.

Controlled water deficits affect grape berry physiology and the resulting wines, with volatile composition being the one of the affected parameters. However, there is a potential disconnect between aromatic maturity and sugar accumulation. Accordingly, the effects of three different water status levels over two growing seasons (2014 and 2015) and two different harvest dates on the aroma compounds from Cabernet Sauvignon wines were studied. Volatile compounds were determined using headspace solid phase microextraction coupled with gas chromatoghraphy/mass spectrometry. Around 45 volatile compounds were determined in the wines and, among these, esters were affected the most, presenting lower concentrations when the most restrictive water treatment was applied in both years. By contrast, volatile acids presented the highest concentrations when the lowest level of irrigation was applied. On the other hand, a delay in harvesting produced an increase in the total amount of volatile compounds in samples from the most restrictive water treatment. These results are coincident with a principal component analysis that indicated a great separation between years, deficit irrigation treatments and harvest dates. The results of the present study suggest that a low water supply had a negative effect on the aromatic potential of wines at a similar ripening stage. However, this effect could be countered by harvesting at a later date. © 2017 Society of Chemical Industry.

Effect of pulsed electric fields on the flavour profile of red-fleshed sweet cherries (Prunus avium var. Stella).

The aim of this research was to study the effect of pulsed electric fields (PEF) on the flavour profile of red-fleshed sweet cherries (Prunus avium variety Stella). The cherry samples were treated at a constant pulse frequency of 100 Hz, a constant pulse width of 20 μs, different electric field strengths between 0.3 and 2.5 kV/cm and specific energy ranging from 31 to 55 kJ/kg. Volatile compounds of samples were analysed using an automated headspace solid phase microextraction (HS–SPME) method coupled with gas chromatography-mass spectrometry (GC–MS). A total of 33 volatile compounds were identified with benzaldehyde, hexanal, (E)-2-hexenal, (Z)-2-hexen-1-ol, and benzyl alcohol being the predominant volatiles in different PEF-treated samples. Aldehydes namely butanal, octanal, 2-octenal, and nonanal, and (Z)-2-hexen-1-ol increased significantly 24 h after PEF treatment at electric field strengths of more than 1.0 kV/cm. Samples incubated for 24 h after PEF treatment (S3) generated higher concentrations of volatiles than samples immediately after PEF treatments (S2). Quantitative results revealed that more flavour volatiles were released and associated with S3 samples after 24 h storage and S2 samples immediately after PEF both with the highest electric field intensities. Interestingly, this study found that the PEF treatments at the applied electric field strength and energy did not result in releasing/producing undesirable flavour compounds.

Physical, chemical and bioactive properties of onion (Allium cepa L.) seed and seed oil

Onion ( Allium cepa L. ) is one of the economically important vegetable crops grown in Turkey. In this study, some physico-chemical and antioxidant properties, volatile compounds and fatty acid composition of ten different onion seeds were investigated. The fatty acid composition and volatile compounds were analyzed by Gas Chromatography (GC) and Gas Chromatography–Mass Spectrometry (GC-MS), respectively. Physico-chemical analysis showed that onion seeds possessed high amount of oil (21.86%-25.86%) and crude protein (15.7%-26.1%). It was determined that moisture content of samples was in the range of 6.49-9.79% while ash content was between 3.58-4.80%. GC results revealed that onion seed oil was rich in linoleic acid (49.42-60.66%) which was followed by oleic and palmitic acid, respectively. The refractive index of seed oils was 1.4555-1.4771. There were a large number of substances such as hydrocarbon, alcohol, acid, ester and sulfur-containing compounds. It was determined that phenethyl alcohol and 1-hexanol were the most abundant volatile compounds in samples. It could be concluded that onion seeds can be utilized in food industry due to their physico-chemical properties and contents of oil and volatile components.

Changes in Volatile Compounds of Black Cumin (Nigella Sativa L.) Seed Oil During Thermal Oxidation

This study examined the oxidation stability and volatile compounds in samples of black cumin seed oil at 60 and 100°C. Oxidative changes of black cumin oils followed by periodic determination of its conjugated dienes and trienes during accelerated conditions (60 and 100°C). Black cumin oil showed high resistance to oxidation during thermal oxidation (60 and 100°C). In addition to oxidative stability, volatile compounds in the oil were determined by headspace solid phase microextraction with gas chromatography-mass spectrometry analysis technique. The major componenent of the oil was p-cymene (44.77%) followed by thymoquinone (28.62%). Some volatile compounds were lost rapidly during thermal oxidation at the end of storage. Levels of thymoquinone, 4-terpineol, α-longipinene, carvacrol, and isolongifolene reduced slowly and remained more stable during storage at two temperatures (60 and 100°C).

Volatile Compounds in Samples of Cork and also Produced by Selected Fungi

The production of volatile compounds by microbial communities of cork samples taken during the cork manufacturing process was investigated. The majority of volatiles were found in samples collected at two stages: resting after the first boiling and nontreated cork disks. Volatile profiles produced by microbiota in both stages are similar. The releasable volatile compounds and 2,4,6-trichloroanisole (TCA) produced in cork-based culture medium by five isolated fungal species in pure and mixed cultures were also analyzed by gas chromatography coupled with mass spectrometry (GC-MS).The results showed that 1-octen-3-ol and esters of fatty acids (medium chain length C8-C20) were the main volatile compounds produced by either pure fungal species or their mixture. Apparently, Penicillium glabrum is the main contributor to the overall volatile composition observed in the mixed culture. The production of releasable TCA on cork cannot be attributed to any of the assayed fungal isolates.

The compositional quality and volatile compounds of samples from the blend of monovarietal olive oils cultivated in Tunisia

SummaryChemlali olive oil has been blended with oils obtained from Oueslati and Chetoui varieties to improve the quality of the former one. Parameters such as acidity, acids compositions, phenol content, oxidative stability and volatile compounds were characterised for various blends Chemlali × Oueslati and Chemlali × Chetoui.The accumulation of volatiles originating from the lipoxygenase pathway in the monovarietal oils was different and closely dependent on the genetic store of each variety. The concentrations appeared to proportionally vary according to the relative proportion of each monovarietal oil in the mixtures. The blending process improved fatty acids by increasing the oleic acid content and decreasing the palmitic and linoleic acids levels of Chemlali oil. At 40% blending, oleic acid increased from 54% to 62%, while palmitic acid decreased from 18.59% to 16% when Oueslati and Chetoui olive oil was used.

Aroma composition of microwave vacuum dried dill (Anethum graveolens L.) stems

The dill variety ‘Superdukat’ stems and leaves grown in the test fields of the Latvia University of Agriculture were harvested in July 2010 and dried by eight microwave vacuum drying programmes at various vacuum, drum rotation speed and specific energy. Volatiles from fresh dill leaves and fresh and dried dill stems were isolated using solid phase micro extraction with DVB/Car/PDMS fibre and analysed by gas chromatography-mass spectrometry. The main aroma compounds of dill leaves are α-phellandrene, dill ether and these results are comparable with those found in literature. In stems a lower concentration of α-phellandrene but a higher percentage of dill ether was detected. Used microwave vacuum drying programme showed the significant influence to the GC total and individual peak areas of aroma compounds. Deviation square sum was calculated to compare the percentage composition of fresh dill and stems versus dried dill stems. The volatile compounds content in dried dill stems obtained using programme 4 is the most similar to the composition of fresh dill leaves and stems, whereas the least similar –dried using programme 3. The highest content of dill stems volatile compounds in samples dried with programme 8 was detected.

Changes in volatile aroma compounds of traditional Chinese-type soy sauce during moromi fermentation and heat treatment

Considering the important influence of longtime (150 day) moromi fermentation and heat treatment on the aroma formation of traditional Chinese-type soy sauce (TCSS), volatile compounds in samples taken from different stages of moromi fermentation and heat treatment were analyzed by solid phase microextraction coupled with gas chromatography-mass spectrometry. Results showed that a total of 76 volatile compounds were identified in all the samples, and most of the volatile compounds were common. During 150 day of moromi fermentation, relative contents of acids, alcohols, aldehydes and ketones, esters, and furan(one)s along with all the sensory attributes of acidic, alcoholic, fruity, caramel-like, smoky, and malty changed greatly. Notably, relative contents of alcohols, aldehydes and ketones along with the sensory intensities of alcoholic, caramel-like, and smoky of heated sample (80°C/60 min) decreased markedly, whereas there were slight increases in relative contents of furan(one)s, phenols, and sulfur-containing compounds of it. Long-time moromi fermentation and heat treatment have significant influence on the formation and relative contents of volatile compounds in TCSS, whereas changes in volatile compounds and their relative contents of the samples were responsible for the differences in sensory attributes.

Ion source with electron ionization for a portable mass spectrometer

An ion source with electron ionization is considered. The charged-particle flow at the exit from this source has a cross section of ∼0.1 × 0.1 mm, an angle spread of 2° × 2°, a relative energy spread of <0.5%, and an energy range of 0.5–3.0 keV. This ion source is intended for systems where an ion beam is focused in two mutually perpendicular directions. The ion source design makes it possible to ionize a sample locally (in a volume of ∼10 mm3), where the concentration of the particles under study exceeds the concentration averaged over the volume of the vacuum chamber of the mass spectrometer by two to three orders of magnitude. The ion-optical properties of the source are numerically simulated, and the optimum parameters of the source are chosen. Examples of the application of the ion source are given for the mass-spectrometric determination of metal salts in aqueous solutions and of gases and volatile compounds in samples in various phase states.

Determination of volatile compounds in Txakoli wine from Biscay by gas chromatography-mass spectrometry

An analytical method combining a Soxhlet extraction and gas chromatography with mass spectrometric detection is proposed for the determination of volatile compounds in samples of Txakoli from Biscay (region located in the north of Spain). The use of direct injection was compared with the results obtained from the organic extract. The extraction of the compounds from the matrix was performed with dichloromethane-hexane (1:1, v/v). Both procedures were applied to the study of Txakoli varieties of wine