Microextraction-gas Chromatography-mass Spectrometry Research Articles

Analysis of flavor change in the industrial production of fungal fermentation based mussel (Mytilus edulis) cooking liquor using a laser irradiation desorption based GC/MS method

The commonly discarded mussel cooking liquor (MCL) of Mytilus edulis is an important resource for industrial preparation of fungus (Aspergillus oryzae) fermented condiment. In this study, the fermentation degree of MCL was evaluated by analyzing the changes of volatile flavor using a newly established laser irradiation desorption (LID) method coupling a 450 nm blue semiconductor laser to a headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME GC/MS). Under the optimized laser conditions (laser power 10 W, irradiation time 5 min, sample volume 3 g), the effect of fungal fermentation was investigated, and a total of 52 volatile compounds in the fermented MCL were detected, such as furans, aromatic compounds, and sulphur and nitrogen containing compounds. By strictly analyzing the characteristic volatiles, the MCL was well processed and the fermentation product showed a desirable and umami flavor, whereas the fishy and burnt smell was roughly removed. Compared with traditional analytical methods, the proposed LID–HS–SPME analysis showed significant characteristic profile and reduced time to only 5 min. The results indicated that the LID–HS–SPME analysis is reliable, efficient, and suitable for industrially used for monitoring the preparation of fungal fermented MCL.

Influence of ultrasonic nebulization extraction, infusion temperatures, and matrices on aroma release and perception of green tea

Tea, as one kind of worldwide popular drink, has complicated aroma profiles. In normal drinking experience, temperatures and matrices affect our perception of tea aroma. In addition, ultrasonic nebulization extraction (UNE), is also viewed as a special way to release tea aroma. In this paper, to investigate the effects of UNE, temperatures, and matrices on the aroma release and profiles expression of Lu'an Guapian tea, solid-phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) and descriptive sensory analysis (DSA) were used. The results showed that the aroma profiles showed significantly difference in different temperatures and matrices. Especially, UNE could efficiently express detailed aroma profiles at low temperature (20 °C), which may be used in the tea aroma evaluation in the future.

Simultaneous determination of 15 BTEX hydroxyl biomarkers in urine by headspace solid-phase microextraction gas chromatography–mass spectrometry

Benzene (B), toluene (T), ethylbenzene (E), o-, m- and p-xylene (o-, m-, p-X) are ubiquitous and frequently exposed to human throughout the environment. Previously published test methods for phenolic biomarkers are not sensitive enough to be detected in most general population groups and require a lot of labor. A simple and convenient headspace solid-phase microextraction (HS-SPME) gas chromatography–mass spectrometry method was described for the simultaneous determination of 15 hydroxyl biomarkers of BTEX in urine. Hydroxyl biomarkers in urine were vaporized and adsorbed onto a selected fiber after enzyme hydrolysis with β-glucuronidase/arylsulfatase. The optimal HS-SPME conditions were achieved with an 85-μm-carboxen-polydimethylsiloxane fiber, an extraction temperature of 70 °C, a heating time of 30 min, and a pH of 4.0. The desorption was performed for 1 min at 250 °C. Under the established conditions, the lowest limits of detection were from 0.02 to 0.15 μg/L in 5.0 mL of urine, and the intra- and inter-day relative standard deviations were less than 12.7% at 0.5, 2.0, 50, and 200 μg/L. The calibration curve demonstrated good linearity with greater than r2 = 0.99 in synthetic urine. This method is convenient, simple, environmentally friendly, and amenable to automation.

Research on Distinguishing Fish Meal Quality Using Different Characteristic Parameters Based on Electronic Nose Technology.

In this paper, a portable electronic nose, that was independently developed, was employed to detect and classify a fish meal of different qualities. SPME-GC-MS (solid phase microextraction gas chromatography mass spectrometry) analysis of fish meal was presented. Due to the large amount of data of the original features detected by the electronic nose, a reasonable selection of the original features was necessary before processing, so as to reduce the dimension. The integral value, wavelet energy value, maximum gradient value, average differential value, relation steady-state response average value and variance value were selected as six different characteristic parameters, to study fish meal samples with different storage time grades. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA), and five recognition modes, which included the multilayer perceptron neural network classification method, random forest classification method, k nearest neighbor algorithm, support vector machine algorithm, and Bayesian classification method, were employed for the classification. The result showed that the RF classification method had the highest accuracy rate for the classification algorithm. The highest accuracy rate for distinguishing fish meal samples with different qualities was achieved using the integral value, stable value, and average differential value. The lowest accuracy rate for distinguishing fish meal samples with different qualities was achieved using the maximum gradient value. This finding shows that the electronic nose can identify fish meal samples with different storage times.

The analysis of organic and inorganic gunshot residue from a single sample

The detection and interpretation of gunshot residue (GSR) can play an important role in the investigation of firearm related incidents. Recently, the potential of organic compounds to provide an additional means to discriminate between GSR and environmental particles, in particular in cases where lead-free ammunition is used, has been highlighted. This work describes a method for the extraction and detection of complementary organic and inorganic compounds from a single GSR sample, using a methodology that makes implementation in the current standard procedure feasible. GSR samples were collected from the shooter’s hands following double and single discharges, using the traditional adhesive carbon aluminium stubs. Analysis of organic compounds was performed using solid-phase microextraction gas chromatography mass spectrometry (SPME-GC–MS), followed by analysis of the traditional inorganic particles using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Detection of both categorised organic GSR compounds (e.g. ethyl centralite, diphenylamine and 2-nitrodiphenylamine) and characteristic inorganic GSR has been achieved. Given the fact that the detected organic GSR compounds are relevant with respect to the confirmation of GSR materials, this method has successfully demonstrated the ability to obtain a total chemical profile from a single GSR sample, which has the potential to increase the probative value of GSR evidence.

Development of a headspace solid-phase microextraction gas chromatography mass spectrometry method for the quantification of volatiles associated with lipid oxidation in whole milk powder using response surface methodology

Lipid oxidation is a major contributor to the deterioration of the sensory quality of fat-containing dairy powders. Hydroperoxides are the primary oxidation products from unsaturated fatty-acids that readily yield a complex mixture of volatile organic compounds that can adversely impact product quality and shelf life. Headspace solid-phase microextraction gas-chromatography mass-spectrometry was chosen to quantify thirteen lipid oxidation compounds in whole milk powder encompassing a range of volatilities and chemical classes. A central composite rotatable design (CCD, α = 1.1) based on a 23 factorial table was used with response surface methodology to optimize the HS-SPME parameters; determined at; 45 min extraction time and 43 °C extraction temperature. The significant model terms were found to be extraction temperature (p < 0.05) and the interaction between time and temperature (p < 0.05). Precision, accuracy, LOD and LOQ were determined and the method was validated for whole milk powder.

A longitudinal study of the faecal microbiome and metabolome of periparturient mares.

BackgroundPeriparturient mares are at increased risk of colic including large colon volvulus, which has a high mortality rate. Alterations in colonic microbiota related to either physiological or management changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population of horses. Although the effect of management changes on the horse faecal microbiota has been investigated, limited work has been conducted to investigate changes in faecal microbiota structure and function in the periparturient period. The objectives of the current study were to investigate temporal stability of the faecal microbiota and volatile organic compounds (VOCs) of the faecal metabolome in periparturient mares.MethodsFaecal samples were collected weekly from five pregnant mares from 3 weeks pre-foaling to 7 weeks post-foaling. The microbiome data was generated by PCR amplification and sequencing of the V1–V2 regions of the bacterial 16S rRNA genes, while the VOC profile was characterised using headspace solid phase microextraction gas chromatography mass spectrometry.ResultsThe mare faecal microbiota was relatively stable over the periparturient period and most variation was associated with individual mares. A small number of operational taxonomic units were found to be significantly differentially abundant between samples collected before and after foaling. A total of 98 VOCs were identified. The total number of VOCs did not vary significantly between individual mares, weeks of sample collection and feeds available to the mares. Three VOCs (decane, 2-pentylfuran, and oct-2-ene) showed significant increase overtime on linear mixed effects modelling analysis. These results suggest that the mare faecal microbiota is structurally and functionally stable during the periparturient period. The findings also suggest that if changes in the gut microbiota are related to development of colic postpartum, altered risk may be due to inherent differences between individual mares. VOCs offer a cost-effective means of looking at the functional changes in the microbiome and warrant further investigation in mares at risk of colic.

Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5 µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10 ± 10.0 wt. % for PLA system and 76.0 ± 3.3 wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.

Prediction of the Biogenic Amines Index of Poultry Meat Using an Electronic Nose.

The biogenic amines index of fresh chicken meat samples during refrigerated storage was predicted based on the headspace analysis using an electronic nose equipped with an array of electrochemical sensors. The reference biogenic amines index values were obtained using dispersive liquid–liquid microextraction–gas chromatography–mass spectrometry. A prototype electronic nose with modular construction and a dedicated sample chamber was used to rapidly analyze the volatile fraction of chicken meat samples, with a single measurement time of five minutes. Back-propagation artificial neural network was used to estimate the biogenic amines index of the samples with a determination coefficient of 0.954 based on ten-fold stratified cross-validation. The results indicate that the determination of the biogenic amines index is a good reference method for studies in which the freshness of meat products is assessed based on headspace analysis and fingerprinting, and that the described electronic device can be used to assess poultry meat freshness based on this value with high accuracy.

Binding of aroma compounds with soy protein isolate in aqueous model: Effect of preheat treatment of soy protein isolate

The interactions between flavors (hexyl acetate [HxAc], heptyl acetate [HpAc], linalyl formate [LiFo], linalyl acetate [LiAc], geraniol, linalool, limonene and myrcene) and soy protein isolate (SPI) were investigated, the influence of flavors structure and preheated SPI (PSPI) were determined by using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME/GC–MS) technology. For HxAc and HpAc, the binding of SPI and the flavors decreased in the order nature > 80 °C > 90 °C > 100 °C PSPI, for LiFo, LiAc, geraniol, and linalool, nature < 80 °C < 90 °C < 100 °C PSPI. For limonene and myrcene, an increase in headspace concentration or “salting out” effect was noticed. The NSPI (nature SPI) and PSPI of 80 °C showed two class binding sites for HxAc and HpAc. These results serve as a foundation for further investigation into the effect of preheating of SPI on its ability to bind to flavor-inducing compounds.

Identification of decomposition volatile organic compounds from surface-deposited and submerged porcine remains

Cadaver dogs are routinely used internationally by police and civilian search organisations to locate human remains on land and in water, yet little is currently known about the volatile organic compounds (VOCs) that are released by a cadaver underwater; how this compares to those given off by a cadaver deposited on land; and ultimately, how this affects the detection of drowned victims by dogs. The aim of this study was to identify the VOCs released by whole porcine (Sus scrofa domesticus) cadavers deposited on the surface and submerged in water using solid phase microextraction gas chromatography mass spectrometry (SPME GC–MS) to ascertain if there are notable differences in decomposition odour depending on the deposition location.For the first time in the UK, the volatile organic compounds (VOCs) from the headspace of decomposing porcine cadavers deposited in both terrestrial and water environments have been detected and identified using SPME-GCMS, including thirteen new VOCs not previously detected from porcine cadavers. Distinct differences were found between the VOCs emitted by porcine cadavers in terrestrial and water environments. In total, seventy-four VOCs were identified from a variety of different chemical classes; carboxylic acids, alcohols, aromatics, aldehydes, ketones, hydrocarbons, esters, ethers, nitrogen compounds and sulphur compounds. Only forty-one VOCs were detected in the headspace of the submerged pigs with seventy detected in the headspace of the surface-deposited pigs. These deposition-dependent differences have important implications for the training of cadaver dogs in the UK. If dog training does not account for these depositional differences, there is potential for human remains to be missed.Whilst the specific odours that elicit a trained response from cadaver dogs remain unknown, this research means that recommendations can be made for the training of cadaver dogs to incorporate different depositions, to account for odour differences and mitigate the possibility of missed human remains operationally.

Comparison of Trihalomethane Formation Using Chlorine-Based Disinfectants Within a Model System; Applications Within Point-of-Use Drinking Water Treatment

© 2019 Clayton, Thorn and Reynolds. Point-of-use (POU) drinking water treatment systems provide solutions for communities where centralized facilities are unavailable. Effective POU systems treat and reduce the number of pathogens in POU water supplies often employing disinfection. Chlorine disinfection results in the formation of disinfection by-products (DBPs), such as trihalomethanes (THMs), through the reaction of chlorine with natural organic matter (NOM) over time. Although THMs are known to be harmful to human health, little is known about their production within POU systems. This study compares the disinfectants; Electrochemically Activated Solutions (ECAS), hypochlorous acid (HOCl), and sodium hypochlorite (NaOCl), with respect to their potential to produce THMs within POU drinking water systems. Headspace solid-phase microextraction (HS-SPME) gas chromatography mass spectrometry (GC-MS) was utilized to quantify THMs in treated water samples containing NOM (Suwannee River humic acid, 4 mg L -1 ). All disinfection treatments were matched to free chlorine concentrations of 1, 3, and 5 mg L -1 , using reaction times of 1, 5, and 10 min. THMs were produced at free chlorine concentrations of 5 mg L -1 and at reaction times of 5 and 10 min for all disinfectants. ECAS or HOCl, resulted in the formation of significantly lower total THM concentrations across all reaction times and free chlorine concentrations, compared to NaOCl. ECAS can be generated at the POU requiring only water, salt and energy for production, and this study demonstrates that its use results in reduced formation of THMs, compared with NaOCl. Further work is required to replicate these findings within scaled-up POU water treatment systems.

Comparison of flavour fingerprint, electronic nose and multivariate analysis for discrimination of extra virgin olive oils.

Flavour is a special way to discriminate extra virgin olive oils (EVOOs) from other aroma plant oils. In this study, different ratios (5, 10, 15, 20, 30, 50, 70 and 100%) of peanut oil (PO), corn oil (CO) and sunflower seed oil (SO) were discriminated from raw EVOO using flavour fingerprint, electronic nose and multivariate analysis. Fifteen different samples of EVOO were selected to establish the flavour fingerprint based on eight common peaks in solid-phase microextraction–gas chromatography–mass spectrometry corresponding to 4-methyl-2-pentanol, (E)-2-hexenal, 1-tridecene, hexyl acetate, (Z)-3-hexenyl acetate, (E)-2-heptenal, nonanal and α-farnesene. Partial least square discrimination analysis (PLS-DA) was used to differentiate EVOOs and mixed oils containing more than 20% of PO, CO and SO. Furthermore, better discrimination efficiency was observed in PLS-DA than PCA (70% of CO and SO), which was equivalent to the correlation coefficient method of the fingerprint (20% of PO, CO and SO). The electronic nose was able to differentiate oil samples from samples containing 5% mixture. The discrimination method was selected based on the actual requirements of quality control.

Rapid discrimination of fungal strains isolated from human skin based on microbial volatile organic profiles

Studies of the microbiota of human skin have gained attention mainly because of its high complexity. Volatile metabolites that emerge from the microbiota play a significant role in fungus metabolism, acting on fungal development, defense, and protection against stress, communication, and pathogenicity. The present study evaluated volatile organic profiles, based on headspace–solid-phase microextraction–gas chromatography–mass spectrometry. We sought to define the optimal experimental conditions for such identification. Chromatograms from 15 fungi were evaluated and discriminated by principal component analysis. The volatile metabolite profiles that were putatively identified in the present study (e.g 2‑isopropyl‑5‑methyl‑cyclohex‑3‑en‑1‑one, 3/2‑methyl‑1‑butanol, isopentyl ethanoate, phenyl ethanol) allowed the discrimination of different microorganisms from human skin. The present methodology may be a more rapid way of identifying microorganisms compared with conventional methods of microbiological identification.

Fragrance transfer between fabrics for forensic reconstruction applications

Sexual assault is a serious crime that often has low conviction rates. Recent literature has demonstrated that there is potential for fragrances to be valuable in forensic reconstructions where there has been contact between individuals. However, developing appropriate evidence bases for understanding the nature of fragrance transfer in these contexts is needed. This article presents three experiments that address the transfer process of fragrances that have been transferred from a primary piece of fabric onto a secondary piece of fabric, in a manner that could occur during an assault. The three variables studied were the ageing time of the fragrances on the first fabric prior to transfer, the contact time between the two fabrics, and lastly the fabric type (of the primary material and the recipient material). The transfer was evaluated using a validated solid phase micro-extraction gas chromatography–mass spectrometry (SPME GC–MS) method. The findings demonstrated that all three variables had an impact on the transfer of fragrances between clothing fabrics. Generally, lower volatility compounds were transferred and recovered in larger amounts than higher volatility compounds. All fragrance compounds were successfully recovered from a secondary piece of fabric even when the contact time was as short as 10 s, and even when the perfume was aged on the primary fabric for as long as 48 h. The nature of the fragrance transfer also depended on the fabric type, so that a clear discrimination was observed between the fragrance transfer that occurred onto a natural fabric (cotton) and onto a synthetic fabric (polyester).

Pod storage with roasting: A tool to diversifying the flavor profiles of dark chocolates produced from ‘bulk’ cocoa beans? (part I: aroma profiling of chocolates)

The impact of pod storage (PS) and roasting temperature (RT) on the aroma profiles of dark chocolates were evaluated. Cocoa liquor samples comprised of ten different combinations of PS and RT, whilst keeping the roasting time fixed at 35 min. Additionally, commercial cocoa liquors from renowned origins (Ecuador, Madagascar, Venezuela, Vietnam, Ivory Coast and Ghana) were acquired for comparison. From these, 70% dark chocolates were produced under the same conditions after which they were subjected to headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS) analysis. Although both PS and RT were found to influence the aroma volatile concentrations, the impact of RT over PS seemed to be greater. An agglomerative hierarchical clustering (AHC) of all chocolates on the basis of their aroma profiles revealed a similar impact as earlier observed, where major clustering of the chocolates was in accordance with the intensity of the roasting process applied. However, within each group, the dissimilarities owing to PS among the chocolates was clearly depicted. Comparatively, chocolates with low (100–120 °C), instead of moderate to high (135–160 °C) RT's, rather showed a low dissimilarity with those from the commercial cocoa liquors of the different origins. Although from the same beans, the diversity of aroma profiles of these chocolates as well as the similitude of some treatments to some chocolates from commercial grade cocoa liquors, unequivocally underscores the possibility for steering diverse distinct flavors from ‘bulk’ cocoa through PS and roasting, with beneficial implications, both from an application and an economic point of view.

Essential oil of Chrysanthemum indicum L.: potential biocontrol agent against plant pathogen Phytophthora nicotianae.

Phytophthora nicotianae is currently considered one of the most devastating oomycete plant pathogens, and its control frequently relies solely on the use of systemic fungicides. There is an urgent need to find environment-friendly control techniques. This study examined the chemical composition, inhibitory activity, and possible modes of action of the essential oil of Chrysanthemum indicum L. (EOC) flower heads against P. nicotianae. The EOC was obtained using hydrodistillation at a 0.15% yielded. It inhibited mycelial growth and spore germination of P. nicotianae at a minimum inhibitory concentration (MIC) of 200μL/L, and exhibited fumigation effects (92.68% inhibition at 157.48μL/L). Marked deformation of P. nicotianae mycelia included deformed tip enlargement, shrinkage, and rupture. Further, 55 and 47 compounds were identified using gas chromatography-mass spectrometry (GC-MS) and headspace solid-phase microextraction (HS-SPME) GC-MS analyses, representing 88.2% and 98.91% of the total EOC, respectively. Monoterpenes (25.77%) and sesquiterpenes (54.14%) were the major components identified using GC-MS, whereas monoterpenes were the main constituents in the HS-SPME GC-MS analysis. The higher proportions of sesquiterpenes and monoterpenes could be responsible for the inhibitory activity of EOC, which increased mycelia membrane permeability and the content of mycelial malondialdehyde (MDA) in a dose-dependent manner. Cell death also occurred. Thus, destruction of the cell wall and membrane might be two modes of action of EOC. Our results would be useful for the development of a new plant source of fungicide for P. nicotianae-induced disease.

Unraveling of the Fishy Off-Flavor in Steam-Treated Rapeseed Oil Using the Sensomics Concept.

The sensomics concept was applied to two steam-treated rapeseed oils, one eliciting a fishy off-flavor (OF) and the other the desired aroma attributes (PC = positive control). After screening the most important odorants via comparative aroma extract dilution analysis, identification experiments and quantitation via stable isotope dilution analysis (SIDA) using gas chromatography-mass spectrometry (GC-MS) were performed. Only five compounds differed in their concentrations by a factor ≥5. In addition, trimethylamine with an intense fishy odor quality and first overlooked by gas chromatography-olfactometry, was only present in OF and finally characterized via ion exchange chromatography and solid phase microextraction GC-MS. For data validation, recombination experiments were performed using all odorants with OAVs ≥ 1, and excellent accordance between GS and OF and their corresponding recombinates was achieved, confirming a correct characterization of all key odorants with trimethylamine as the only odorant responsible for the fishy off-flavor.

Characteristic volatiles fingerprints and changes of volatile compounds in fresh and dried Tricholoma matsutake Singer by HS-GC-IMS and HS-SPME-GC–MS

The present study was to analyze the water dynamics of Tricholoma matsutake Singer during hot air drying by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI), and to investigate the volatile compounds in the pileus, upper stipe and lower stipe of fresh and dried Tricholoma matsutake Singer by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS). Fresh samples were dried at 60 °C for 12 h. With the T2i relaxation times decreasing, the water migrated from the inner toward the periphery and then expelled during drying. The characteristic volatiles fingerprints of different parts of fresh and dried samples were established by HS-GC-IMS. The significant differences in volatile compounds were observed among different parts of the fresh sample and C8 compounds (70%–97%) were the principal components. After drying, the concentration of C8 compounds dramatically decreased and some volatile compounds (hexanal, heptanal, 2(5H)-furanone, acetophenone, nonanal, benzeneacetaldehyde) were formed. Thus, hot air treatment affected the volatile compounds in Tricholoma matsutake Singer.

Volatile fingerprints and biomarkers of three representative kiwifruit cultivars obtained by headspace solid-phase microextraction gas chromatography mass spectrometry and chemometrics

Volatile aroma of kiwifruit is a mixture of complicated and time-dependent compounds, and thereby the study of these compounds required distinguished analytical techniques as well as robust data analysis techniques. In this work, we report on the volatile fingerprints and biomarkers of three representative kiwifruit cultivars with commercial importance using headspace solid-phase microextraction gas chromatography-mass spectrometric (HS-SPME-GC-MS) coupled with multivariate analysis. As a result, 95 volatiles have been analyzed from the fingerprints, and ultimately six of which were identified as volatile biomarkers of the kiwifruit cultivars studied, which are formic acid octyl ester, 2-Methylbicyclo[4.3.0]non-1(6)-ene, 1-ethoxy-2,4-hexadiene, and 2-methyl-5-(1-methylethyl)-bicyclo[3.1.0]hex-2-ene for Jintao (A. chinensis), and 1-methoxy-2-methyl-benzene and (E,E)-2,4-heptadienal for Cuiyu (A. deliciosa), respectively. Since the samples of each cultivar were in various maturities, these compounds could be taken as the maturity-independent volatile biomarkers for the kiwifruit cultivars, which would be valuable for marker-assisted flavour breeding in the kiwifruit production.