Classes Of Volatile Organic Compounds Research Articles

Enhancing Electronic Nose Performance by Feature Selection Using an Improved Grey Wolf Optimization Based Algorithm.

Electronic nose is a kind of widely-used artificial olfactory system for the detection and classification of volatile organic compounds. The high dimensionality of data collected by electronic noses can hinder the process of pattern recognition. Thus, the feature selection is an essential stage in building a robust and accurate model for gas recognition. This paper proposed an improved grey wolf optimizer (GWO) based algorithm for feature selection and applied it on electronic nose data for the first time. Two mechanisms are employed for the proposed algorithm. The first mechanism contains two novel binary transform approaches, which are used for searching feature subset from electronic nose data that maximizing the classification accuracy while minimizing the number of features. The second mechanism is based on the adaptive restart approach, which attempts to further enhance the search capability and stability of the algorithm. The proposed algorithm is compared with five efficient feature selection algorithms on three electronic nose data sets. Three classifiers and multiple assessment indicators are used to evaluate the performance of algorithm. The experimental results show that the proposed algorithm can effectively select the feature subsets that are conducive to gas recognition, which can improve the performance of the electronic nose.

Long-lasting direct capture of xylene from air using covalent-triazine frameworks through multiple C-H…π weak interactions

Xylene molecules are a class of volatile organic compounds (VOCs) in the air that are harmful to human health. It is difficult to selectively capture xylenes from the air using existing porous sorbents, due to unspecific and insufficient sorbent/sorbate interactions. We herein report a series of covalent-triazine frameworks (CTFs) that enable selectively capturing of xylene compounds with high adsorption capacities at low pressure. The best-performing CTF material (CTF-2-400), which is comprised of biphenyl and triazine motifs, can adsorb a remarkable amount of o-xylene (358 mg g−1), m-xylene (392 mg g−1) and p-xylene (523 mg g−1) at 25 °C, outperforming most of emerging porous adsorbents. Its ability to capture low-concentration xylenes from the air has been demonstrated using a column breakthrough measurement. The column packed with CTF-2-400 (1 g) continuously captured xylene from the flowing air (~1300 ppm; 10 mL min−1) for 192 h; by contrast, the commercial activated carbon lost its xylene capture capability after only 35 h under the same conditions. We find that the xylene adsorption capacities of the evaluated CTF adsorbents are unrelated to their pore widths or surface areas, and infer that the multiple C-H…π interactions between the CTF framework and xylene molecules account for the observed excellent xylene capture performance.

Development and application of a solid-phase microextraction gas cromatography mass spectrometry method for analysing volatile organic compounds produced during cooking.

In the last decades, there is more awareness on the impact on human health of pollutants emitted during cooking processes, both from commercial and from domestic activities. In this study, a new method exploiting solid-phase microextraction and gas chromatography coupled to mass spectrometry (SPME-GC-MS) was developed to analyse the volatile organic compounds (VOCs) emitted during cooking. The air above the cooking plate was sampled using a polyethylene terephthalate olfactometric bag that allows to transport the sample to the instrument location and to perform the SPME extraction of the sampled air. The efficiency of different extraction systems and different extraction times (1, 8, 16, and 24 h) was evaluated in order to obtain sufficient sensitivity. Thus, the proposed system, combining the use of olfactometric bags and SPME-GC-MS, was applied for the first time to study VOCs emitted during cooking allowing to perform the analysis, even on samples produced in sites far from the instrument location, in an easy way and with instrumentations available in most of laboratories. Then, the method was applied to assess the efficiency of odour filters used in common kitchen hoods, using deep frying of potatoes in sunflower oil as cooking model system. VOCs were analysed in the air before and after passage through the filter, calculating then percentages of dejection for the different classes of VOCs that resulted to be in the range 31-77%.

Adsorption of volatile organic compounds by industrial porous materials: Impact of relative humidity

Abstract In this study, the adsorption of several classes of volatile organic compounds by materials with a range of pore size distributions and chemistries were assessed gravimetrically in both dry and wet carrier gas conditions. Measurements carried out at room temperature, and a range of relative humidity values (RH) from 0 to 70%, reflected real-world conditions similar to those of indoor air. Dry removal performance appeared to be dependent on the surface area of adsorbents and, for polar compounds, the relative hydrophobicity of the material. Performance of sorbents with hydrophilic surface chemistry, such as silica gel and molecular sieve 13X, decreased drastically with small increases in pre-exposed humidity. Activated charcoal and high-silica faujasite Y retained their capacities for toluene in relative humidities up to 50% and 70% respectively, with their selectivity for non-polar species credited to hydrophobic pore structure and low water vapour uptake. These conclusions help to emphasise the importance of process humidity as a key parameter when designing or selecting adsorbents in realistic process conditions. Additionally, the methods used in this study provide a simple and reproducible way of testing porous materials for applications requiring or involving high levels of relative humidity.

Identification of plastic toys contaminated with volatile organic compounds using QCM gas sensor array

In this paper, we propose a fast and easy-to-use analytical method to identify the children toys contaminated with potentially dangerous substances from the class of volatile organic compounds (VOCs). It is shown that the use of cross-sensitive gas sensor array based on piezoelectric sensors, modified with different sorbents, allows reliable recognition of items with the elevated levels of VOCs. Applying chemometric methods for processing of the sensor array data, it is possible to classify the toys into clean and hazardous ones with sensitivity and accuracy around 96%. Taking into account the simplicity of the suggested procedure, it appears to be an attractive option for cost-effective pre-screening of potentially dangerous plastic toys in comparison with the expensive and time-consuming chromatographic methods.

Rose volatile compounds allow the design of new control strategies for the western flower thrips (Frankliniella occidentalis)

Western flower thrips (WFT) is a serious pest on rose crops. Semiochemical-mediated WFT–rose interactions have been studied because different rose cultivars interact differently with WFT. Thus, the volatile organic compounds (VOCs) emitted from six commercial rose cultivars were collected in vivo by headspace-solid phase microextraction (HS-SPME) in greenhouses and analyzed by gas chromatography coupled to mass spectrometry. Qualitative and quantitative differences were found among the six cultivars, and terpenes were the most abundant class of VOCs, followed by aromatic hydrocarbons, and esters. Principal component analysis (PCA) was further applied to identify the VOCs with the greatest influence on the differentiation of the cultivars. Cramer’s phi coefficients between the VOCs emitted by each cultivar and their thrips incidence were also estimated. Accordingly, nine VOCs that could generate chemotactic responses in WFT were selected for testing in a linear track olfactometer, and seven of them elicited responses in female WFT at at least to one of the test concentrations. Thrips showed significant positive chemotaxis (attraction) to six compounds, and of these, the highest response was detected for (±)-theaspirane. These findings suggest that the tested VOCs could be used to develop a new strategy for the control of WFT on roses.

Compuestos orgánicos volátiles de plantas inducidos por insectos: situación actual en México


 Las plantas producen y emiten compuestos orgánicos volátiles, generalmente son mezclas que están compuestas por terpenos, derivados de ácidos grasos y compuestos aromáticos. Los compuestos orgánicos volátiles sirven a las plantas para: reproducción, atraer polinizadores o dispersores de semillas, como defensa para repeler insectos o detener la colonización por bacterias y hongos fitopatógenos, para atraer enemigos naturales de herbívoros y como mensajeros intraespecíficos e interespecíficos. Las plantas emiten algunos volátiles especialmente cuando las partes vegetativas se exponen a estimulo abiótico o biótico. Considerando lo antes expuesto, se realizó una revisión bibliográfica, siendo el objetivo del presente trabajo dar a conocer la clasificación de los compuestos orgánicos volátiles de las plantas, describir y señalar las características de las técnicas de extracción e identificación de los compuestos orgánicos volátiles, presentar los avances reportados en la literatura científica acerca de estos compuestos inducidos por insectos y su situación actual en México.

Floral volatiles and visitors: A meta‐network of associations in a natural community

Abstract Chemosensory communication between flowers and pollinators is a fundamental component of terrestrial biodiversity, given the importance of olfaction to foraging animals. In this respect, exploring chemically mediated interspecific interactions in natural assemblies may provide novel insights into the ecofunctional significance of volatile organic compounds (VOCs) for plant–insect co‐evolution. However, multispecies datasets of associations between plant semiochemicals and arthropods are still very rare and tend to lack community context. Here, we present the first insect–floral VOC meta‐network using plant–pollinator visitation data and the plants’ floral scent blends, collected in a Mediterranean scrubland. We assembled the insect–VOC meta‐network by substituting each plant species in the plant–pollinator network with the blend of VOCs it emits. Furthermore, we identified the modules of the network that is the most densely connected insect–VOC groups. After describing the role of the species in the network, we focused on the bees of the community, and by building phylogenetically informed GLS models, we found the species traits predicting the degree of chemical specialization. Modularity analysis of the meta‐network revealed tight associations between several classes of VOCs and pollinator groups. Linkage patterns suggest positive associations between (a) Megachilidae bees and sesquiterpenes, (b) Apidae and Andrenidae bees and benzenoids/phenylpropanoids, and (c) wasps, C6 green‐leaf volatiles and specific terpenoids. Benzenoids were found to be the least influential and most specialized chemical class in the community, whereas sesquiterpenes represented the most influential one. Furthermore, the degree of chemical generalization of the bees in the meta‐network was significantly associated with their ecological generalization, body mass and phenology, whereas their contribution to the network's structure was related to their level of sociality. Synthesis. Our findings help to disclose the ecofunctional significance of the floral volatile landscape and contribute novel testable hypotheses on the behavioural trends and chemical niches of pollinators in a natural community. The insect–volatilome meta‐network is thus shown to be advantageous for detecting and visualizing patterns of chemically mediated interspecific interactions. Given the ubiquity of chemosensory biocommunication, our approach can be applied for investigating various types of ecological interactions in community contexts.

Selective adsorption of BTEX on calixarene-based molecular coordination network determined by 13C NMR spectroscopy

Benzene, toluene, ethylbenzene, and xylenes (BTEX), a class of volatile organic compounds, are harmful pollutants but also very important precursors in organic industrial chemistry. Among different approaches used for the BTEX treatment, the adsorption technology has been recognized as an efficient approach because it allows to recover and reuse both adsorbent and adsorbate. However, the selective adsorption of the components is the key factor for the efficiency of the process. With this view, calixarene-based materials are very promising due to the unique cavity-like structure of the ligand. An unprecedented coordination network based on calixarene of an interesting nanosheet-like morphology was prepared via a solvothermal layer method. This material showed selectivity for non-polar molecules with remarkable uptake of benzene (38.33 mmol/g). In addition, a simple and useful method of BTEX quantification, through 13C NMR spectroscopy, is reported here for the first time.

In vitro antibacterial activity and volatile characterisation of organic Apis mellifera ligustica (Spinola, 1906) beeswax ethanol extracts

Apis mellifera beeswax is synthesized from honey sugars and secreted by specialized glands situated in the ventral side of the abdomen of worker bees from 12 to 18 days old. It is also characterized by several therapeutic properties of great interest for human health with applications for healing bruises, inflammation, burns and with antimicrobial activity. The aims of this investigation were to assess the antibacterial activity of three organic beeswax samples from different locations and to evaluate their volatile composition with HS-SPME/GC-MS analysis. The beeswax's volatile organic compounds (VOC) included 82 molecules belonging to different chemical classes, such as aldehydes, hydrocarbons, alcohols, esters, ketones, organic acids, and terpenes. The total VOC contents was 35 ± 5 and 40 ± 2 ppm for samples A and B, respectively. Aldehydes were the main class of VOC in the beeswax ethanol extracts, particularly linear aldehydes such as octanal, nonanal and decanal. Minimal inhibitory concentration (MIC) showed that Pseudomonas aeruginosa and Listeria monocytogenes were inhibited by all beeswax samples. Salmonella Typhimurium was the most resistant bacterial strain. Against the 13 Staphylococcus aureus wild strains tested, beeswax samples A was the most effective, followed by sample B and C.

Elucidation of headspace volatilome in Polianthes tuberosa flower for identifying non-invasive biomarkers

To date, no volatilome study has used the dynamic headspace method, based on adsorption–desorption principle, to investigate the chemical divergence of floral fragrance in Polianthes tuberosa L. (cv. Calcutta Single). This study proposes a suitable adsorbent/solvent combination to analyze emitted volatiles from this flower, allowing for a qualitative, and tentatively quantitative, floral volatilome using a holistic approach. Here, 13 different adsorbent/solvent combinations were used to determine the total emitted volatilome, from in situ and plucked flowers, using headspace and gas chromatography–mass spectrometry. Several adsorbent/solvent combinations were explored to optimize trapping the most diverse range of volatile organic compounds in a single attempt. A mixture of porous polymers (Porapak or Tenax) with graphite or charcoal were best when combined with dichloromethane as the eluting solvent. Among the two solvents, dichloromethane showed better desorption efficiency than hexane. For better elucidation of any specific chemical group, suitable adsorbent and solvent should be chosen properly or the quantity or quality of the volatilome captured would be compromised. Three distinct classes of volatile organic compounds were categorized: aromatics, terpenes, and fatty acid derivatives. Maximum diversity, along with quantity, was found with the aromatic group. Total chemical divergence of volatilome from in situ and freshly plucked flowers was similar. Benzyl salicylate, methyl 2-amino benzoate, germacrene D, farnesal, farnesyl acetate, and delta decalactone may be considered biomarkers for the origin of P. tuberosa floral scent.

An Optimized E-nose for Efficient Volatile Sensing and Discrimination.

Electronic noses (E-noses), are usually composed by an array of sensors with different selectivities towards classes of VOCs (Volatile Organic Compounds). These devices have been applied to a variety of fields, including environmental protection, public safety, food and beverage industries, cosmetics, and clinical diagnostics. This work demonstrates that it is possible to classify eleven VOCs from different chemical classes using a single gas sensing biomaterial that changes its optical properties in the presence of VOCs. To accomplish this, an in-house built E-nose, tailor-made for the novel class of gas sensing biomaterials, was improved and combined with powerful machine learning techniques. The device comprises a delivery system, a detection system and a data acquisition and control system. It was designed to be stable, miniaturized and easy-to-handle. The data collected was pre-processed and features and curve fitting parameters were extracted from the original response. A recursive feature selection method was applied to select the best features, and then a Support Vector Machine classifier was implemented to distinguish the eleven distinct VOCs. The results show that the followed methodology allowed the classification of all the VOCs tested with 94.6% (± 0.9%) accuracy.

Simultaneous determination of fifteen multiclass organic pollutants in human saliva and serum by liquid chromatography-tandem ultraviolet/fluorescence detection: A validated method.

A quick and inexpensive validated method, based on sample treatment by liquid-liquid microextraction followed by liquid chromatography (LC) coupled with ultraviolet tandem fluorescence detection is proposed for the determination of 15 multiclass pollutants both in serum and in saliva, as a simple and easy to draw matrix. The method was set up and validated according to European guidelines. The compounds of interest include some endocrine-disrupting chemicals (i.e. bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AF, bisphenol A diglycidyl ether, bisphenol M, diethylhexyl phthalate, monoethylhexyl phthalate, triclosan and 4-nonylphenol), as well as other pollutants belonging to the class of volatile organic compounds (2-chlorophenol, 1,2 dichlorobenzene, 1,2,4,5-tetrachlorobenzene). The limits of quantifications ranged from 2.28 × 10-3 μg mL-1 (bisphenol A diglycidyl ether) to 6.29 μg mL-1 (diethylhexyl phthalate), while those of detection ranged from 0.068 × 10-3 μg mL-1 (bisphenol A diglycidyl ether) to 1.031 μg mL-1 (diethylhexyl phthalate). To test method suitability, it was applied to real saliva and serum samples of healthy human volunteers and was found to meet the demands of the laboratories handling simple and relatively inexpensive equipment for screening oriented at rapid and reliable contamination assessment of a population.

Applications of Electronic-Nose Technologies for Noninvasive Early Detection of Plant, Animal and Human Diseases

The development of electronic-nose (e-nose) technologies for disease diagnostics was initiated in the biomedical field for detection of biotic (microbial) causes of human diseases during the mid-1980s. The use of e-nose devices for disease-diagnostic applications subsequently was extended to plant and animal hosts through the invention of new gas-sensing instrument types and disease-detection methods with sensor arrays developed and adapted for additional host types and chemical classes of volatile organic compounds (VOCs) closely associated with individual diseases. Considerable progress in animal disease detection using e-noses in combination with metabolomics has been accomplished in the field of veterinary medicine with new important discoveries of biomarker metabolites and aroma profiles for major infectious diseases of livestock, wildlife, and fish from both terrestrial and aquaculture pathology research. Progress in the discovery of new e-nose technologies developed for biomedical applications has exploded with new information and methods for diagnostic sampling and disease detection, identification of key chemical disease biomarkers, improvements in sensor designs, algorithms for discriminant analysis, and greater, more widespread testing of efficacy in clinical trials. This review summarizes progressive advancements in utilizing these specialized gas-sensing devices for numerous diagnostic applications involving noninvasive early detections of plant, animal, and human diseases.

Miniaturized micromachined gas chromatography with universal and selective detectors for targeted volatile compounds analysis

An effective analytical strategy for targeted analysis of volatile organic compounds which combines two orthogonal separation mechanisms and multiple tunable detection in a compact transportable analytical system is introduced. This strategy uses a commercially available micromachined gas chromatograph comprising a micromachined on-board thermal conductivity detector. The chromatograph capability is enhanced by incorporating a modified diode array detector and a radio frequency modulated ion mobility spectrometry microfabricated electromechanical system. The analytical platform offers powerful detection capabilities of individual compounds and various classes of volatile organic compounds with improved provisional confirmatory capability. The transportable micromachined gas chromatograph employs field replaceable conventional capillary columns for the separation of analytes. The use of a silicon micromachined sample introduction device affords fast injection to minimize band broadening with fast chromatographic separation rendered in the order of minutes. Advantaged synergy also includes leveraging the resolving power of gas chromatography to minimize charge exchange in the ionization chamber of the differential mobility spectrometer for improved detector performance. Performance of this scalable and transportable analytical system is demonstrated with relevant volatile compounds such as acetaldehyde, acetone, carbon disulfide, benzene, and ethyl butyrate having a day-to-day variability less than 5% and with a high degree of reliability.

GC-MS aroma characterization of vegetable matrices: Focus on 3-alkyl-2-methoxypyrazines.

Abstract3‐Alkyl‐2‐methoxypyrazines (MPs) are a very important class of volatile organic compounds (VOCs), intensively characterizing the aroma of several food products including fruits and vegetables. Due to the very low orthonasal sensory threshold, low amounts of MPs may act as key positive or negative aroma compounds. The analysis of these volatiles in foods is then remarkably important, and it may be very challenging as confirmed by the scarce literature focused on MPs, particularly with respect to quantitative data. In the attempt to fill this gap, in this work, presence and quantification of MPs in four different vegetables, namely, green bell pepper (Capsicum annuum L. var grossum), green pea (Pisum sativum L. and Pisum spp), carrot (Daucus carota subsp sativus), and cucumber (Cucumis sativus L.) have been investigated. Two different volatile extraction techniques (solid phase microextraction [SPME] and simultaneous distillation‐extraction [SDE]) in conjunction with VOC qualitative analysis by gas chromatography‐mass spectrometry (GC‐MS) methods were applied. Solid phase microextraction coupled with GC‐MS in single ion monitoring (SIM) mode showed the best performances in sensitivity to detect MPs on the different vegetable matrices. Therefore, a headspace (HS) SPME‐GC‐MS quantitative method was developed and optimized, and dominant MPs quantified. 3‐Isopropyl‐2‐methoxypyrazine (IPMP), 3‐sec‐butyl‐2‐methoxypyrazine (sBMP), and 3‐isobutyl‐2‐methoxypyrazine (IBMP) have been detected and quantified in all the vegetables. 3‐Isopropyl‐2‐methoxypyrazine was the prevalent MP in peas and cucumber while IBMP in bell pepper. These MPs were detected for the first time in carrot and cucumber. Finally, sBMP has been confirmed to be the most important MP in carrot. The developed method allowed to characterize the VOC pattern and, in particular, to quantify MPs in four vegetables. Results highlight the feasibility of further applications of the analytical approach to determine MPs in other food matrices where an excessive amount of these aromas may negatively affect their flavor (eg, coffee).

SnO2 Nanostructured Thin Films for Room-Temperature Gas Sensing of Volatile Organic Compounds.

We demonstrated room-temperature gas sensing of volatile organic compounds (VOCs) using SnO2 nanostructured thin films grown via the aerosol chemical vapor deposition process at deposition temperatures ranging from 450 to 600 °C. We investigated the film's sensing response to the presence of three classes of VOCs: apolar, monopolar, and biopolar. The synthesis process was optimized, with the most robust response observed for films grown at 550 °C as compared to other temperatures. The role of film morphology, exposed surface planes, and oxygen defects were explored using experimental techniques and theoretical calculations to improve the understanding of the room-temperature gas sensing mechanism, which is proposed to be through the direct adsorption of VOCs on the sensor surface. Overall, the improved understanding of the material characteristics that enable room-temperature sensing gained in this work will be beneficial for the design and application of metal oxide gas sensors at room temperature.

Performances of Different Metabolic Lactobacillus Groups During the Fermentation of Pizza Doughs Processed from Semolina

The main hypothesis of this work is that facultative and obligate heterofermentative Lactobacillus species can differently impact the final characteristics of pizza. The objective was to evaluate separately the behaviors of the obligate heterofermentative species (OHS), such as Lactobacillus sanfranciscensis, Lactobacillus brevis, and Lactobacillus rossiae, and the facultative heterofermentative species (FHS), including Lactobacillus plantarum, and Lactobacillus curvatus, in the sourdoughs to be used for pizza production. The production of the experimental pizzas was carried out with semolina (Triticum turgidum L. ssp. durum). The acidification process—which was followed by pH, total titratable acidity (TTA), and lactic acid bacteria (LAB) development—indicated for all of the experimental trials that the kinetics is comparable to those of the controls. The fermentation quotient of the FHS trial was particularly higher than that of the other trials, including the control production performed with a sourdough inoculum used in an artisanal bakery. The dominance of the added strains indicated the clear persistence of L. sanfranciscensis PON100336, L. brevis 200571, and L. plantarum PON100148 in the obligate–facultative heterofermentative species (OFHS) trial. The pizzas were baked without seasoning in order to investigate weight loss, color, morphology, and a generation of volatile organic compounds (VOCs). The data showed the differences among trials regarding the inocula. Eight classes of VOCs were detected in the pizza samples with aldehydes, esters, alcohols, and acids as major compounds. The sensory attributes were significantly different for the judges and the pizzas. The multivariate statistical approach found marked differences among the trials. The results indicated that the application of mixed cultures of the facultative heterofermentative species of Lactobacillus determined high quality pizzas.

Inoculation of Brevibacterium linens RS16 in Oryza sativa genotypes enhanced salinity resistance: Impacts on photosynthetic traits and foliar volatile emissions

The emission of volatiles in response to salt stress in rice cultivars has not been studied much to date. Studies addressing the regulation of stress induced volatile emission by halotolerant plant growth promoting bacteria containing ACC (1-aminocyclopropane-1-carboxylate) deaminase are also limited. The objective of the present study was to investigate the salt alleviation potential of bacteria by regulating photosynthetic characteristics and volatile emissions in rice cultivars, and to compare the effects of the bacteria inoculation and salt responses between two rice genotypes. The interactive effects of soil salinity (0, 50, and 100 mM NaCl) and inoculation with Brevibacterium linens RS16 on ACC accumulation, ACC oxidase activity, carbon assimilation and stress volatile emissions after stress application were studied in the moderately salt resistant (FL478) and the salt-sensitive (IR29) rice (Oryza sativa L.) cultivars. It was observed that salt stress reduced foliage photosynthetic rate, but induced foliage ACC accumulation, foliage ACC oxidase activity, and the emissions of all the major classes of volatile organic compounds (VOCs) including the lipoxygenase pathway volatiles, light-weight oxygenated volatiles, long-chained saturated aldehydes, benzenoids, geranylgeranyl diphosphate pathway products, and mono- and sesquiterpenes. All these characteristics scaled up quantitatively with increasing salt stress. The effects of salt stress were more pronounced in the salt-sensitive genotype IR29 compared to the moderately salt resistant FL478 genotype. However, the bacterial inoculation significantly enhanced photosynthesis, and decreased ACC accumulation and the ACC oxidase activity, and VOC emissions both in control and salt-treated plants. Taken together, these results suggested that the ACC deaminase-containing Brevibacterium linens RS16 reduces the temporal regulation of VOC emissions and increases the plant physiological activity by reducing the availability of ethylene precursor ACC and the ACC oxidase activity under salt stress.

Combining color chart, colorimetric measurement and chemical compounds for postharvest quality of white wine grapes.

This paper provides data for the potential use of a color chart to establish the best quality of white wine grapes destined for postharvest processing. Grechetto, Vermentino and Muscat of Alexandria white wine grape varieties were tested by sampling berries at different dates during their quality attribute evolution. A color chart and reflectance spectrocolorimeter were used in combination with analyses of total carotenoids and chlorophylls in all three varieties and of volatile organic compounds (VOCs) in Grechetto alone. Total carotenoids decreased from 0.85 to 0.76 µg g-1 in Grechetto berries and from 0.70 to 0.46 µg g-1 in Vermentino berries while increased from 0.70 to 0.80 µg g-1 in Muscat berries during ripening. Total chlorophylls decreased in all varieties, and a strict correlation was found between hue angle (measured by color chart or spectrocolorimeter) and chlorophyll disappearance, with R2 ranging from 0.81 to 0.95 depending on the variety. VOCs were only measured in Grechetto grapes, and a significant increase in glycosylation was found with ripening. The concentration of different classes of VOCs exhibited a clear decrease during ripening, except for terpenoids and esters which showed a peak at the beginning. The benzenoid class reached the highest concentration, which was almost 50% of the total. Cluster analysis using Ward's method enabled the best grape quality to be identified. This experimental work highlights that a color chart is cheap and easy to use to define the right quality stage for white wine grapes. The color chart enabled the enochemical features to be matched with the VOC results for the aromatic maturity of Grechetto. © 2018 Society of Chemical Industry.