Solid-phase Microextraction In Combination Research Articles

Volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening and senescence using HS–SPME with GC–MS

The volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening stages and senescence times was determined by headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry. The HS-SPME-GC-MS analysis allowed the identification of 46 metabolites that produce the metabolic fingerprint of this fruit, the major compounds at all ripening stages and senescence times were ethyl butanoate, methyl butanoate, β-myrcene and eucalyptol. The composition in the different stages was subjected to principal component analysis (PCA), which explained 77.3% of the total variance in the principal components. It allowed to classify the samples by ripening stages and senescence times and it was corroborated with K-means clustering and dendrogram analyses. Through multivariate analyses PCA, partial least squares-discriminant analysis (PLS-DA), and heatmap it was possible to determine volatiles methyl (E)-2-hexenoate, 4-tert-butylcyclohexyl acetate, methyl benzoate, methyl (Z)-3-hexenoate, 3-methylbutyl acetate, β-thujene, cis-3-hexenol, hexanal and trans-2-hexenal as potential markers in the ripening stages, while volatiles propyl butanoate, ethyl octanoate, ethyl acetate, ethyl butanoate, β-myrcene and estragol predominated in the senescence times. HS-SPME-GC-MS analysis of volatiles in combination with the chemometric approach used in this research allowed to make a clear distinction between ripening stages and senescence times in common red variety of tree tomato pulp.

Identification of quality markers for the geographical and botanical differentiation of Mediterranean prickly pears based on conventional physicochemical parameters, volatile compounds, sugars and colour

Seventy-four prickly pear samples grown in Mediterranean countries (Cyprus, Greece, Italy and Spain) and 43 prickly pear samples, from 3 different Cypriot varieties (Yellow, Red and Spineless), were characterized and differentiated according to geographical and botanical origin. Prickly pear conventional quality parameters (pH, electrical conductivity, titratable acidity, moisture content, crude fat and protein, total carbohydrates and ash) were determined using official methods of analysis. Colour parameters were determined using HunterLab tristimulus colorimetry and individual sugars using UPLC–MS/MS. Volatile compounds were identified and semi-quantified using solid-phase microextraction in combination with gas chromatography–mass spectrometry. Multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) were used to analyze the experimental data. Results showed that the combination of physicochemical parameters and volatiles gave a correct differentiation rate of 80.8% according to geographical origin while the combination of physicochemical parameters gave a correct differentiation rate 95.3% according to botanical origin using the cross-validation method.

Chemical composition of volatile components in the honey of some species of stingless bees

Using the technique of headspace solid-phase microextraction in combination with gas chromatography and mass spectrometric detection (HS-SPME/GC-MS), the composition of the volatile organic compounds (VOCs) of the honey of four species of stingless bees was studied in comparison with the honey of Apis mellifera bees. Peaks for 284 volatile components were registered on the chromatograms. Only eight components were present in all six studied samples. A high level of specificity in the composition of VOCs is a prerequisite for differentiating honey produced by different types of stingless bees and honey bees. Several specific features have been identified that are characteristic of the composition of VOCs in the honey of each species of stingless bees. These characteristics can be used to distinguish it from the honey of A. mellifera. The data obtained indicate the applicability of the HS-SPME/GC-MS technique for establishing the origin and for quality control of stingless bee honey.

Characterization and Differentiation of Fresh Orange Juice Variety Based on Conventional Physicochemical Parameters, Flavonoids, and Volatile Compounds Using Chemometrics.

The present study focused on the possibility of differentiating fresh-unprocessed orange juice according to botanical origin (variety), based on the use of conventional physico-chemical parameters, flavonoids, and volatile compounds, in combination with chemometrics. For this purpose, oranges from seven different varieties were collected during the harvest years of 2013–2014 and 2014–2015 from central and southern Greece. The physico-chemical parameters that were determined included: electrical conductivity, acidity, pH, and total soluble solids. The flavonoids: hesperidin, neohespseridin, quercetin, naringin, and naringenin were determined using high-performance liquid chromatography (HPLC-DAD). Finally, volatile compounds were determined using headspace solid-phase micro-extraction in combination with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Statistical treatment of data by multivariate techniques showed that orange juice variety had a significant (p < 0.05) impact on the above analytical parameters. The classification rate for the differentiation of orange juice according to orange variety using multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) was 89.3%, based on the cross-validation method.

Volatile composition of the morning breath

We have measured the composition of volatile organic compounds (VOCs) in the morning breath of 30 healthy individuals before and after tooth brushing. The concentrations of VOCs in the breath samples were measured with proton-transfer-reaction time-of-flight mass spectrometry (MS) and further identification was performed with a combination of solid phase microextraction and offline gas chromatography–MS. We hypothesize that compounds, whose concentrations significantly decreased in the breath after tooth brushing are largely of microbial origin. In this study, we found 35 such VOCs. Out of these, 33 have been previously connected to different oral niches, such as salivary and subgingival bacteria. We also compared the concentrations of the 35 VOCs found in increased amounts in the morning breath to their respective odor thresholds to evaluate their ability to cause odor. Compounds that could contribute to the breath odor include many volatile sulfur compounds, such as methanethiol, hydrogen sulfide, dimethyl sulfide, and 2-methyl-1-propanethiol, but also other VOCs, such as acetic acid, butyric acid, valeric acid, acetaldehyde, octanal, phenol, indole, ammonia, isoprene, and methyl methacrylate.

Using Solid-Phase Microextraction Coupled with Reactive Carbon Fiber Ionization-Mass Spectrometry for the Detection of Aflatoxin B1 from Complex Samples

Aflatoxin B1 (AFB1) is a common mycotoxin present in agricultural and food products. Therefore, rapid screening methods must be developed for AFB1 detection with high sensitivity and good selectivity. In this study, we developed an analytical method based on the combination of solid-phase microextraction (SPME) with carbon fiber ionization (CFI)-mass spectrometry (MS) to detect the presence of trace AFB1 from complex samples. A pencil lead (type 2B, length: ~2.5 cm) with a sharp end (diameter: ~150 μm) was used as the SPME fiber and the ionization emitter in CFI-MS analysis. Owing to the graphite structure of the pencil lead, AFB1 can be trapped on the pencil lead through π–π interactions. After adsorbing AFB1, the pencil lead was directly introduced in a pipette tip (length: ~0.7 cm; tip inner diameter: ~0.6 mm), placed close (~1 mm) to the inlet of the mass spectrometer, and applied with a high voltage (−4.5 kV) for in situ AFB1 elution and CFI-MS analysis. A direct electric contact on the SPME-CFI setup was not required. Followed by the introduction of an elution solvent (10 μL) (acetonitrile/ethanol/deionized water, 2:2:1 (v/v/v)) to the pipette tip, electrospray ionization was generated from the elution solvent containing AFB1 for CFI-MS analysis. A reactive SPME-CFI-MS strategy was employed to further identify AFB1 and improve elution capacity using our approach. Butylamine was added to the elution solvent, which was then introduced to the pipette tip inserted with the SPME fiber. Butylamine-derivatized AFB1 was readily generated and appeared in the resultant SPME-CFI mass spectrum. The lowest detectable concentration against AFB1 using our approach was ~1.25 nM. Our method can distinguish AFB1 from AFG1 in a mixture and can be used for the detection of trace AFB1 in complex peanut extract samples.

Unravelling the key aroma compounds in the characteristic fragrance of Dendrobium officinale flowers for potential industrial application

Dendrobium officinale Kimura et Migo, one of the most important orchids because of its medicinal and edible value, has a typical Dendrobium Sw. flora scent, which has great application potential and commercial value to be characterized. The aroma-active compounds originating from D. officinale fresh flowers (DFF) were investigated using a sensomics approach. A combined solid phase microextraction and solvent-assisted flavor evaporation method were used to accurately capture the overall aromatic profile. Exactly 34 odorants were detected and identified by aroma extract dilution analysis (AEDA) coupled with gas chromatography/olfactometry−mass spectrometry (GC/O−MS) in DFF, of which nine odorants had a flavor dilution (FD) factor ≥27. All 34 odorants were further quantified. The odor activity values (OAVs) were calculated with the highest value of 7444, in which 18 compounds were confirmed to be key odorants, including 1-octen-3-ol, hexanal, nonanal, phenylacetaldehyde, linalool, 4-oxoisophorone, theaspirane, methyl salicylate, etc. Among the studies above, 42 out of 78 volatiles and 14 out of 34 odorants were identified in DFF for the first time. Then, the aroma profile of the DFF was simulated successfully by aroma recombination experiments based on the quantitation results, and the omission test suggested that alcohols are the decisive type of compounds in the DFF key odorants. In addition, a progressive addition test showed that the aroma recombinate prepared with 18 reference key odorants was able to reconstruct the characteristic aroma of DFF. In comparison, the recombinate constituted by mixing all 34 reference odorants in the same concentrations as determined in the DDF sample could mimic the flower scent and closely match the sensory attributes of the original D. officinale fresh flower.

Group-type quantitative analysis of flavor compounds in ripening avocados.

Avocados are a superfood gaining popularity in people's diet. Profiling and quantifying the volatiles associated with flavor can further help in understanding the fruit. However, this is challenging due to relatively low abundance of volatile compounds. The complex mixtures inherent to avocado flavor can result in coelutions using classical chromatographic techniques. To overcome these challenges, solid-phase microextraction was used to extract and preconcentrate volatiles, then separated and quantified using two-dimensional gas chromatography with a flame ionization detector. This technique enhances separation power and produces well-ordered chromatograms, allowing for templated groupings of compounds of similar chemical composition into regions. Using the flame ionization detector, an average response factor was determined and used for quantification of these templated group-type regions, as well as individual compounds. This group-type quantification improved the overall precision of compound classes in 50 avocados by at least a factor of 2, when compared to that of the individual components. Overall, the abundance of associated flavor groups, such as terpenes and alcohols decreased, whereas aldehyde groups remained constant throughout ripening. The combination of solid-phase microextraction with two-dimensional gas chromatography and group-type quantification allows for an overall better understanding of the volatiles associated with flavor of avocados.

Identifying volatile in vitro biomarkers for oral bacteria with proton-transfer-reaction mass spectrometry and gas chromatography\u2013mass spectrometry

We have measured the volatile fingerprints of four pathogenic oral bacteria connected to periodontal disease and dental abscess: Porphyromonas gingivalis (three separate strains), Prevotella intermedia, Prevotella nigrescens and Tannerella forsythia. Volatile fingerprints were measured in vitro from the headspace gas of the bacteria cultured on agar. Concrete identification of new and previously reported bacterial volatiles were performed by a combination of solid phase microextraction (SPME) and offline gas chromatography–mass spectrometry (GC–MS). We also studied the effect of the reduced electric field strength (E/N) on the fragmentation patterns of bacterial volatiles in online proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS). We aimed to discover possible new biomarkers for the studied oral bacteria, as well as to validate the combination of GC–MS and PTR-MS for volatile analysis. Some of the most promising compounds produced include: 1-Methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ), indole, and a cascade of sulphur compounds, such as methanethiol, dimethyl disulphide (DMDS) and dimethyl trisulphide (DMTS). We also found that several compounds, especially alcohols, aldehydes and esters, fragment significantly with the PTR-MS method, when high E/N values are used. We conclude that the studied oral bacteria can be separated by their volatile fingerprints in vitro, which could have importance in clinical and laboratory environments. In addition, using softer ionization conditions can improve the performance of the PTR-MS method in the volatile analysis of certain compounds.

Combination of solid phase microextraction and low energy electron ionisation gas chromatography-quadrupole time-of-flight mass spectrometry to meet the challenges of flavour analysis

The flavour analysis of volatile compounds remains challenging not only because of their diversity in properties and dynamic range, but also due to the high background noise from food matrix constituents. To improve sensitivity and specificity for a multiclass range of compounds, a combination of solid phase micro-extraction (SPME) devices and low energy electron ionisation (LE-EI) was proposed for the analysis of 36 volatile compounds, using coffee as a model matrix. From a pre-evaluation of devices and extraction modes, the combined use of direct immersion-stir bar sorptive extraction and headspace-thin-film SPME (SBSE-TFSPME) was selected to increase compound recovery, and further optimised for extraction temperature (88 °C) and time (110 min). Furthermore, to complement sample preparation by improving method specificity, a LE-EI technique was developed by evaluating the effect of ionisation energy, source temperature, and emission current on the formation of the diagnostic molecular ions and their preservation. This LE-EI method (15 eV, 150 °C, 0.3 μA) was validated with SBSE-TFSPME as a complete workflow in coffee matrices, and was found to possess good repeatability (intra-day RSD: 1.6–7.3 %), intermediate precision (inter-day RSD: 4.1–12.2 %), and linearity (R2 > 0.98). Even for complex coffee samples, the method detection limit reached the pg/mL range (e.g. 2,4,5-trimethylthiazole was detected at 15 pg/mL). In conclusion, this study provided insights on the potential of SPME and LE-EI to improve the sensitivity and specificity of analysis for a range of volatile compounds from food and other complex matrices.

Profiling of volatile compounds in Japanese sake stored in sherry casks using solid phase microextraction/gas chromatography/mass spectrometry analysis

The combination of solid phase microextraction (SPME) and gas chromatograph-mass spectrometer (GC-MS) is frequently used for comprehensive analysis of aroma components in foods because it can be used to easily analyze volatile components, allowing saving of the amount of solvent used. In this study, SPME-GC-MS analysis of sake samples before and after sherry cask storage was performed to investigate the special flavor derived from sherry cask storage. A GC column with polyethylene glycol as the stationary phase, which is the first choice for volatile component analysis, was used. However, the peak of the acid having a carbonyl group was tailed due to its bond with the hydroxyl group of the stationary phase. In the analysis of sake samples, a large and tailing peak derived from the large amount of fatty acids in Japanese sake was observed. Additionally, it was not possible to analyze other co-eluting components. To overcome this problem, a novel extraction condition was examined using SPME and tris (hydroxymethyl) aminomethane (Tris). By adding Tris solution to sake, the fatty acid peak was removed successfully, thereby facilitating analysis of the peaks of compounds co-eluting with fatty acids and comprehensive analysis of the aroma components in sake. Furthermore, a comparative analysis of sake before and after storage in sherry cask showed that levels of fatty alcohols, organic acid esters, fatty acid esters, and terpenes increased significantly after storage in sherry cask, suggesting that these ingredients might constitute the special flavor of sherry cask-stored sake.

Assessment of solid phase microextraction as a sample preparation tool for untargeted analysis of brain tissue using liquid chromatography-mass spectrometry

This work presents an evaluation of solid-phase microextraction (SPME) SPME in combination with liquid chromatography-high resolution mass spectrometry (LC-HRMS) as an analytical approach for untargeted brain analysis. The study included a characterization of the metabolite coverage provided by C18, mixed-mode (MM, with benzene sulfonic acid and C18 functionalities), and hydrophilic lipophilic balanced (HLB) particles as sorbents in SPME coatings after extraction from cow brain homogenate at static conditions. The effects of desorption solvent, extraction time, and chromatographic modes on the metabolite features detected were investigated. Method precision and absolute matrix effects were also assessed. Among the main findings of this work, it was observed that all three tested coating chemistries were able to provide comparable brain tissue information. HLB provided higher responses for polar metabolites; however, as these fibers were prepared in-house, higher inter-fiber relative standard deviations were also observed. C18 and HLB coatings offered similar responses with respect to lipid-related features, whereas MM and C18 provided the best results in terms of method precision. Our results also showed that the use of methanol is essential for effective desorption of non-polar metabolites. Using a reversed-phase chromatographic method, an average of 800 and 1200 brain metabolite features detected in positive and negative modes, respectively, met inter-fibre RSD values below 30% (n=4) after removal of fibre and solvent artefacts from the associated datasets. For features detected using a lipidomics method, a total of 900 and 1800 features detected using C18 fibers in positive and negative mode, respectively, met the same criteria. In terms of absolute matrix effects, the majority of the model metabolites tested showed values between 80 and 120%, which are within the acceptable range. Overall, the findings of this work lay the foundation for further optimization of parameters for SPME-LC-HRMS methods suitable for in vivo and ex vivo brain (and other tissue) untargeted studies, and support the applicability of this approach for non-destructive tissue metabolomics.

Differences of characteristic aroma compounds in Rougui tea leaves with different roasting temperatures analyzed by switchable GC-O-MS and GC × GC-O-MS and sensory evaluation.

Roasting, an important process to refine Wuyi Rock tea, could impart different types of aroma to the final products. This study focuses on the differences in aroma characteristics among three kinds of refined teas, named light fire (LF), moderate fire (MF), and high fire (HF). A combination of solid phase microextraction (SPME) and a switchable system between GC-O-MS and GC × GC-O-MS was utilized to identify the odorants. In total, 97 aroma-active compounds could be smelled at the sniffing port, comprising alcohols, aldehydes, ketones, esters, heterocycles, and terpenes. However, only 52 obtained r-OAV >1. Significant differences were uncovered by the application of principal component analysis (PCA) and partial least squares regression (PLSR). Thereby, MF and HF had a more similar aroma profile, while in LF samples, alcohols, aliphatic aldehydes and some ketones were responsible for the aroma profile, such as (E,E)-2,4-hexadienal, octanal, hexanal, (E,Z)-2,6-nonadienal, (E)-β-ionone, 3-octen-2-one etc. Strecker aldehydes had a great impact on the aroma of MF, including 2-methylpropanal, 2-methylbutanal, 3-methylbutanal etc. Some N-heterocyclic compounds also affected the overall aroma, for instance, 6-methyl-2-ethylpyrazine. In HF, the majority of aroma compounds increased with increasing roasting temperature, especially N-heterocyclic compounds as well as furfural and 5-methyl-2-furancarboxaldehyde, which are all closely related to the Maillard reaction. Besides, 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol, trans-linalooloxide and 2-nonanone also remarkably influenced the aroma of HF. In addition, it was supposed that most amino acids that participated in the Maillard reaction during roasting were decomposed from the compounds that combined with tea polyphenols and amino acids.

Comparative Evaluation of Key Aroma-Active Compounds in Sweet Osmanthus (Osmanthus fragrans Lour.) with Different Enzymatic Treatments

Sweet osmanthus (Osmanthus fragrans Lour.) (OF) is one of the ten most famous flowers in China for its unique and delicate fragrance. A combined solid-phase microextraction and solvent-assisted flavor evaporation method was used to accurately capture the overall aromatic profile and characterize the predominant odorants of fresh osmanthus with the help of gas chromatography (GC)-olfactometry and comprehensive two-dimensional GC-quadrupole time-of-flight mass spectrometry (GC × GC-QTOF-MS). Twenty-six volatiles were identified for the first time in OF. A total of 23 potent odorants, dominated by monoterpene oxides and C6 aliphatic aldehydes, were identified. The efficacy of pectinase, β-glucosidase, and their combination on the aroma enhancement of OF was evaluated by quantitation of the target aroma components using GC-triple quadrupole-MS. The total concentration of key aroma components increased in all three enzyme treatment groups, and the increase was more significant in two β-glucosidase-treated groups. Changes in odor activity values and odor spectrum values of key odorants indicated that the pectinase-treated sample had more prominent floral, green, and potato-like scents. In contrast, the β-glucosidase-treated sample had more dominant floral, woody, almond-like, and fruity notes but less green odor, which was confirmed by sensory evaluation. β-Glucosidase and pectinase complement one another very well, and together, promote a remarkable aroma enhancement in OF.

Fabrication of monolith-based solid-phase microextraction for effective extraction of total chromium in milk and tea samples prior to HPLC/DAD analysis

A convenient, sensitive and low-cost approach for the determination of trace levels of total chromium in milk and tea samples was developed by combination of solid-phase microextraction (SPME) and HPLC/DAD. To meet the chromatographic separation and UV detection, Cr(VI) was reacted with sodium diethyldithiocarbamatetrihydrate to form Cr coordination compound. According to the chemical properties of the complex, a new sorbent based on porous monolithic material (PMM) was fabricated and employed as the extraction phase of SPME. The prepared PMM displayed satisfying enrichment ability for Cr complex. Under the most appropriate parameters, the linear ranges for chromium were 1.0–500 μg/kg and 0.5–300 μg/kg in milk and tea samples, respectively, with good correlation coefficients (R2 greater than 0.99). The limits of detection for chromium were as low as 0.11 μg/kg and 0.092 μg/kg in milk and tea samples, separately. The RSDs for method precision were in the range of 0.23–8.6%. The reliability and applicability of introduced method was successfully demonstrated by quantification of low contents of total chromium in milk and tea samples. The recoveries at three fortified levels varied from 83.4% to 112%, and the RSDs (n = 3) were in the range of 2.1% and 8.9%. Compared with existing methods, the current approach exhibited some merits such as satisfactory sensitivity, low consumption of sample and high cost effectiveness.

Multivariate Cherry Quality Assessment Using Morphological, Biochemical and Volatile Compound Traits

ABSTRACT This study was carried out to evaluate fruit quality of five sweet cherry cultivars grown in Morocco, namely, Burlat, Van, Cerisette, Napoleon and Coeur de pigeon. Significant differences (p˂0.05) were observed across the five cultivars in fruit weight (5.24–8.72 g), geometric mean diameter (14.22–16.36 mm), pH (3.48–4.12), soluble solid content (17.70–24.50 °Brix), total phenolics (426.44–485.69 mg GAE/100 g fresh weight (fw)), total proanthocyanidins (51.17–131.20 mg CE/100 g fw) and total anthocyanins (194.53–267.67 mg cya-3-glu/100 g fw). The antioxidant activity was evaluated by three assays. The values were 11.96–21.04, 16.48–63.96 and 9.62–15.65 mmol TE/g for DPPH scavenging test, FRAP and ABTS, respectively. Volatile compounds were identified and semi-quantified in sweet cherry fruit using solid-phase microextraction in combination with gas chromatography/mass spectrometry (SPME-GC/MS). Nine volatile compounds (benzaldehyde, nonanal, ethyl hexanoate, ethyl octanoate, γ-terpinene, β-pinene, limonene, linalool and 2-ethyl-1-hexanol) were detected in all sweet cherry cultivars. Aldehydes compounds were the most abundant in sweet cherry aroma, followed by terpenes and esters. Correlation between all parameters showed varying trends.

Quantitation of pyrazines in roasted green tea by infrared-assisted extraction coupled to headspace solid-phase microextraction in combination with GC-QqQ-MS/MS

Pyrazines play an important role in the characteristic flavor of roasted green tea due to powerful strong odours and low sensory thresholds. It is important to analyze these compounds reliably and rapidly in roasted green tea. In this study, infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) and gas chromatography-triple quadrupole-tandem mass spectrometry (GC-QqQ-MS/MS) were developed and validated to determine the pyrazines in roasted green tea. Good linear correlation coefficients (0.9955–0.9996) were obtained over the concentration ranges of 10–5000 ng/mL. The limits of detection (LODs) and limits of quantification (LOQs) for the pyrazines were in the range of 1.46–3.27 ng/mL and 4.89–10.90 ng/mL, respectively. The average recoveries varied from 84% to 119%. The method was used to analyze the pyrazines in roasted green tea manufactured by different final firing methods, the results revealed that microwave final firing method had maximum contents of pyrazines, and significantly improved the aroma quality. In addition, there were great disparities of pyrazines in flatten-shaped green tea and strip-shaped green tea according to the appearance. The result is expected to better understand the role of pyrazines related to aroma quality of roasted green tea and improve processing technology.

Identifikacija isparljivih aromatičnih jedinjenja voćnih rakija metodom mikroekstrakcije na čvrstoj fazi u kombinaciji sa gasnom hromatografijom i masenom spektrometrijom

The optimization of the headspace solid-phase microextraction in combination with the gas chromatography-mass spectrometry (HS-SPME-GC/MS) for the qualitative identification of the aroma compounds in fruit spirits (Williams, plum spirit, grape spirit , apricot spirit) was the subject of the presented paper. The SPME extraction conditions (temperature, time, and NaCl amount) have been varied in order to achieve the more efficient chromatographic separation of the gas mixtures, to efficiently salt-out a higher number of less volatile compounds, and to save the energy during the sample preparation. Optimal parameters were determined as: T = 40 °C; m NaCl = 2 g; dilution = 10 times. According to the results obtained, the analyzed samples of Serbian fruit spirits produced from different fruits have a comparable composition of volatile aroma compounds to whiskey. The detection and definition of specific compounds that are "fingerprint" of fruit spirits could be an efficient method of the product authentication developing.

Inhibitory Abilities of Bacillus Isolates and Their Culture Filtrates against the Gray Mold Caused by Botrytis cinerea on Postharvest Fruit.

Botrytis cinerea, a major phytopathogenic fungus, has been reported to infect more than 200 crop species worldwide, and it causes massive losses in yield. The aim of this study was to evaluate the inhibitory abilities and effects of Bacillus amyloliquefaciens RS-25, Bacillus licheniformis MG-4, Bacillus subtilis Z-14, and Bacillus subtilis Pnf-4 and their culture filtrates and extracts against the gray mold caused by B. cinerea on postharvest tomato, strawberry, and grapefruit. The results revealed that the cells of Z-14, culture filtrate of RS-25, and cells of Z-14 showed the strongest biocontrol activity against the gray mold on the strawberry, grape, and tomato fruit, respectively. All the strains produced volatile organic compounds (VOCs), and the VOCs of Pnf-4 displayed the highest inhibition values. Based on headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry, esters accounted for the largest percentage of the VOCs produced by RS-25, MG-4, Z-14, and Pnf-4 (36.80%, 29.58%, 30.78%, and 36.26%, respectively). All the strains showed potent cellulase and protease activities, but no chitinase activity. RS-25, Z-14, and MG-4, but not Pnf-4, grew on chrome azurol S agar, and an orange halo was formed around the colonies. All the strains showed biofilm formation, fruit colonization, and lipopeptide production, which may be the main modes of action of the antagonists against B. cinerea on the fruit. This study provides the basis for developing natural biocontrol agents against the gray mold caused by B. cinerea on postharvest fruit.

Interrelation of Volatile Organic Compounds and Sensory Properties of Alternative and Torrefied Wood Pellets

The increasing demand for wood pellets on the market, which is caused by their excellent combustion properties, inspires the production as well as the utilization of alternative biomass pellets as fuel. However, the emission of volatile organic compounds gives pellet materials a distinct odor or off-odor, which is directly perceived by the end user. Thus, there is an urgent need for knowledge about the emitted volatile organic compounds and their potential formation pathways as well as their contributions to odor properties of the pellets. In this study, pellets made of biomass energy crops (i.e., straw or miscanthus), byproducts from the food industry (i.e., rapeseed, grapevine, or DDGS (dried distillers grains with solubles from beer production)), or eucalyptus, as well as torrefied pinewood and torrefied sprucewood were investigated with respect to the emitted volatile compounds and their possible impact on the pellet odor. Headspace solid-phase microextraction in combination with gas chromatography–mass spectrometry was used to enrich, separate, and identify the compounds. Techniques used in sensory science were applied to obtain information about the odor properties of the samples. A total of 59 volatile compounds (acids, aldehydes and ketones, alcohols, terpenes, heterocyclic compounds, and phenolic compounds) were identified with different compound ratios in the investigated materials. The use of multivariate statistical data analysis provided deep insight into product–compound interrelation. For pellets produced from bioenergy crops, as well as from byproducts from the food industry, the sensory properties of the pellets reflected the odor properties of the raw material. With respect to the volatiles from torrefied pellets, those volatiles that are formed during the torrefaction procedure dominate the odor of the torrefied pellets covering the genuine odor of the utilized wood. The results of this work serve as a substantiated basis for future production of pellets from alternative raw materials.