Volatile Phenols Research Articles

Use of AirMixing M.I.® resonance waves to produce aroma richer Sangiovese wine without sulphites addition in a sustainable way

In recent years, wine without sulphite addition has grown increasingly popular. In this work, resonance waves (AirMixing M.I.®) were applied to Sangiovese must in fermentation to produce wine without sulphite addition, monitoring the fermentation kinetics and analyzing polyphenols and volatile organic compounds (VOCs) extraction. Resonance waves were created by injecting compressed air into a 10 hL stainless steel tank filled with Sangiovese must, without pumping-over/delestage, and no sulphites in all the process (AM). Control wine was produced using pumping-over/delestage and adding sulphur dioxide. After 4 months in bottles, simulating the commercial habit used to sell in spring the last year wine, volatile acidity was significantly lower in AM wine, while total anthocyanins, trans-resveratrol and free quercetin were significantly higher. Among free (VOCs), the classes of terpenes and benzenoids were significantly higher in the Control wine while the classes of aldehydes, alcohols, volatile phenols, lactones and pyrazine were in the AM wine. Unlike free VOCs, in glycosylated VOCs, terpenes and benzenoids were significantly higher in AM wine. In conclusion, resonance waves permit to speed up the fermentation increasing phenols extraction and producing wines with excellent maintenance of VOCs, requiring less energy and labor, and thus being more economically and environmentally sustainable.

Aromatic Characterization of Graševina Wines from Slavonia and Podunavlje Sub-Regions

This study investigated the chemical aromatic profiles of 60 volatile organic compounds (VOCs), including 21 terpenes, 6 norisoprenoids, 6 volatile phenols, 4 C-6 alcohols, and 23 esters, in Graševina wines originating from Slavonia and Podunavlje sub-regions (Croatia). Headspace solid-phase microextraction gas chromatography coupled with mass spectrometric detection (HS-SPME-GCMS) was used to assess 60 VOCs, and a novel HS-SPME-GCMS method for the determination of terpenes and norisoprenoids was developed and validated. Statistical analysis found no significant differences between VOCs present in Graševina wines and others wines (Chardonnay and Pinot gris); nonetheless, comparison of VOC fingerprints between different wines from the same producer showed that four terpenes (α-terpinene, γ-terpinene, 1,4-cineol, and 4-terpineol) were present in higher amounts in Graševina wines when compared to other wines. By exclusively examining VOCs within Graševina wines through the utilization of a heatmap and hierarchical clustering, a distinct visualization of samples and VOCs emerged, highlighting the vintage effect. Simultaneously, a partial least squares discriminant analysis model was developed with a confidence interval of 95%, demonstrating a noticeable distinction between samples originating from the western and eastern regions. Furthermore, by employing the heatmap using only VOCs from the terpene and norisoprenoidic groups, a clear separation of samples into two groups was observed based on geographical origin; namely, higher concentrations of norisoprenoids and terpenes were observed in the Slavonia sub-region. These results suggest that terpenes and norisoprenoids to a lower extent may be valuable aromatic markers for the regional typicality of Graševina wines.

Dynamic changes in metabolomics and flavoromics during industrial scale fermentation of Chinese traditional soy sauce

Flavor substances are crucial to the quality of soy sauce and closely related to the intermediate metabolites. This study systematically explored the dynamic changes in physicochemical characteristics, metabolomics and flavoromics during traditional Chinese soy sauce fermentation. The results indicated that the amino acid nitrogen gradually increased to 0.95 g/100 mL on the 13th day and then stabilized, and the changes of reducing sugars increased to 66.40 mg/mL on the 7th day and then slowly decreased. A total of 90 volatile compounds and 1172 non-volatile metabolites were detected. In the early fermentation period (1–7 day), alcohols, aldehydes and ketones were the main volatile compounds, but as fermentation proceeded, phenols and esters gradually accumulated. The total content of volatile compounds, mainly alcohols and phenols, reached the highest value on the 23rd day. Non-volatile metabolites were mainly amino acids, organic acids, lipids and carbohydrates, and the content and types of varied with fermentation time. KEGG analysis indicates there were significant changes in the proline and arginine metabolism in the middle and late periods (7–28 day) compared to the early fermentation period. Correlation analysis indicating a delicate balance between the transformation of metabolites and the formation of volatile compounds in traditional Chinese soy sauce.

Characterization of key aroma compounds in cold brew coffee prepared by negative-pressure extraction technology and its changes during storage

Cold brew coffee is gaining popularity among consumers; however, its extraction is time consuming and it has a short shelf life. This study employed negative-pressure extraction to reduce the extraction time of cold brew coffee. Ninety-four volatile compounds, including furans, ketones, pyrazines, esters, aldehydes, azoles, pyrroles, phenols, pyridines, acids, and alcohols, were identified. The concentrations of these compounds varied with the extraction time. Sensory evaluation revealed the optimal extraction time to be 5 h, significantly enhancing the extraction efficiency of cold brew coffee. At this point, 9 key aroma compounds (OAV ≥1) were identified, with 2,3-diethyl-5-methyl-pyrazine and 3-ethyl-2,5-dimethyl-pyrazine predominant in the sample. We also investigated the changes in the physicochemical properties and key aroma compounds of cold brew coffee during refrigerated storage. The results showed a significant increase in acidity and total acid content, a notable decrease in antioxidant activity, and a decline in key aroma compounds with the extension of storage time. These findings indicated that the deterioration of cold brew coffee might be caused by the degradation of aroma compounds, leading to changes in the coffee's physicochemical properties. This study provides theoretical support for accelerating the extraction of cold brew coffee and extending its shelf life.

Ambient Monitoring Portable Sensor Node for Robot-Based Applications.

The leakage of gases and chemical vapors is a common accident in laboratory processes that requires a rapid response to avoid harmful effects if humans and instruments are exposed to this leakage. In this paper, the performance of a portable sensor node designed for integration with mobile and stationary robots used to transport chemical samples in automated laboratories was tested and evaluated. The sensor node has four main layers for executing several functions, such as power management, control and data preprocessing, sensing gases and environmental parameters, and communication and data transmission. The responses of three metal oxide semiconductor sensors, BME680, ENS160, and SGP41, integrated into the sensing layer have been recorded for various volumes of selected chemicals and volatile organic compounds, including ammonia, pentane, tetrahydrofuran, butanol, phenol, xylene, benzene, ethanol, methanol, acetone, toluene, and isopropanol. For mobile applications, the sensor node was attached to a sample holder on a mobile robot (ASTI ProBOT L). In addition, the sensor nodes were positioned close to automation systems, including stationary robots. The experimental results revealed that the tested sensors have a different response to the tested volumes and can be used efficiently for hazardous gas leakage detection and monitoring.

Efficient flocculation pretreatment of coal gasification wastewater by halophilic bacterium Halovibrio variabilis TG-5.

The isolated halophilic bacterial strain Halovibrio variabilis TG-5 showed a good performance in the pretreatment of coal gasification wastewater. With the optimum culture conditions of pH = 7, a temperature of 46°C, and a salinity of 15%, the chemical oxygen demand and volatile phenol content of pretreated wastewater were decreased to 1721mg/L and 94mg/L, respectively. The removal rates of chemical oxygen demand and volatile phenol were over 90% and 70%, respectively. At the optimum salinity conditions of 15%, the total yield of intracellular compatible solutes and the extracellular transient released yield under hypotonic conditions were increased to 6.88g/L and 3.45g/L, respectively. The essential compatible solutes such as L-lysine, L-valine, and betaine were important in flocculation mechanism in wastewater pretreatment. This study provided a new method for pretreating coal gasification wastewater by halophilic microorganisms, and revealed the crucial roles of compatible solutes in the flocculation process.

The Potential of NIR Spectroscopy and Chemometrics to Discriminate Roast Degrees and Predict Volatiles in Coffee.

This study aimed to establish a rapid and practical method for monitoring and predicting volatile compounds during coffee roasting using near-infrared (NIR) spectroscopy coupled with chemometrics. Washed Arabica coffee beans from Ethiopia and Congo were roasted to industry-validated light, medium, and dark degrees. Concurrent analysis of the samples was performed using gas chromatography-mass spectrometry (GC-MS) and NIR spectroscopy, generating datasets for partial least squares (PLS) regression analysis. The results showed that NIR spectroscopy successfully differentiated the differently roasted samples, similar to the discrimination achieved by GC-MS. This finding highlights the potential of NIR spectroscopy as a rapid tool for monitoring and standardizing the degree of coffee roasting in the industry. A PLS regression model was developed using Ethiopian samples to explore the feasibility of NIR spectroscopy to indirectly measure the volatiles that are important in classifying the roast degree. For PLSR, the data underwent autoscaling as a preprocessing step, and the optimal number of latent variables (LVs) was determined through cross-validation, utilizing the root mean squared error (RMSE). The model was further validated using Congo samples and successfully predicted (with R2 values > 0.75 and low error) over 20 volatile compounds, including furans, ketones, phenols, and pyridines. Overall, this study demonstrates the potential of NIR spectroscopy as a practical and rapid method to complement current techniques for monitoring and predicting volatile compounds during the coffee roasting process.

Engineering Multinanochannel Polymer-Intercalated Graphene Oxide Membrane for Strict Volatile Sieving in Membrane Distillation.

Graphene oxide (GO) membranes enabled by subnanosized diffusion channels are promising to separate small species in membrane distillation (MD). However, the challenge of effectively excluding small volatiles in MD persists due to the severe swelling and subsequent increase in GO interlamination spacing upon direct contact with the hot feed. To address this issue, we implemented a design in which a polymer is confined between the GO interlaminations, creating predominantly 2D nanochannels centered around 0.57 nm with an average membrane pore size of 0.30 nm. Compared to the virginal GO membrane, the polymer-intercalated GO membrane exhibits superior antiswelling performance, particularly at a high feed temperature of 60 °C. Remarkably, the modified membrane exhibited a high flux of approximately 52 L m-2 h-1 and rejection rates of about 100% for small ions and 98% for volatile phenol, with a temperature difference of 40 °C. Molecular dynamics simulations suggest that the sieving mechanisms for ions and volatiles are facilitated by the narrowed nanochannels within the polymer network situated between the 2D nanochannels of GO interlaminations. Concurrently, the unrestricted permeation of water molecules through the multinanochannel GO membrane encourages high-flux desalination of complex hypersaline wastewater.

Molecular recognition-induced structural flexibility in ZIF-71

The adsorption performance of ZIF-71 towards two common volatile organic compounds, chlorobenzene and phenol, has been evaluated using a number of experimental techniques and Grand Canonical Monte Carlo (GCMC) simulations.

Exploring Variation in Grape and Wine Volatile Phenol Glycoconjugates to Improve Evaluation of Smoke Taint Risk

Exploring Variation in Grape and Wine Volatile Phenol Glycoconjugates to Improve Evaluation of Smoke Taint Risk

Electrosynthesis of metal coordination cluster Zn5/polyaniline composite coating for headspace solid phase microextraction of nine volatile phenolic compounds in aqueous samples

A novel polyaniline (PANI) coating doped with Zn5(H2Ln)6(NO3)4 (Zn5, H3Ln=(1,2-bis(benzimidazole-2-yl)-ethenol) cluster on a stainless-steel wire was prepared by the electrodeposition method for the headspace solid-phase microextraction (HS-SPME) of nine volatile phenols. Scanning electron microscopy, Fourier transform infrared spectrometry, energy dispersive spectrometry and thermogravimetry were employed to characterize the morphology, composition, structure and thermal stability of the Zn5/PANI composite coating. The extraction efficiency of the Zn5/PANI composite coating for nine phenols was nearly 2 times higher than that of pure PANI coating. After the extraction conditions were optimized, an HS-SPME-gas chromatography-flame ionization detector (GC-FID) method was developed for the determination of nine phenols in water samples. The HS-SPME-GC-FID method had superior analytical performance with good linearities (0.05–50.0 μg/L) and low limits of detection (0.01–0.08 μg/L). Then, the proposed method was successfully applied for the determination of nine phenols in water samples with satisfactory recoveries (79.4–110.0%).

Evaluation of Functional Spray Coatings for Mitigating the Uptake of Volatile Phenols by Pinot Noir Wine Grapes via Blocking, Absorption, and/or Adsorption.

Spray coatings have shown promising potential in preventing the uptake of smoke phenols from wildfires into wine grapes. Three cellulose nanofiber-based coatings with low methoxyl pectin or varying concentrations of chitosan were made into films and their potential for blocking, absorption, or adsorption of phenols (guaiacol, m-cresol, and syringol) was evaluated using a custom-built smoke diffusion box. The coatings were also applied to Pinot noir grapes in a vineyard. GC-MS analysis for smoke phenols from headspace gases of diffusion study and extractions of films indicated that chitosan-based films can block guaiacol and syringol, and all films are able to capture m-cresol. The type of coating and application time in a vineyard did not affect (P < 0.05) physicochemical properties, size, and weight of the berries, whereas chitosan-based coatings resulted in a higher anthocyanin content of berries. This study provided new information about the key mechanisms (i.e., blocking phenols) of coatings to mitigate smoke phenol uptake in wine grapes.

Institute of Chemistry, Chernyshevsky Saratov State University

New test tools made of nanofibers based on polyamide-6 (PA-6) for the sorption preconcentration of some phenols as their azo derivatives followed by colorimetric determination are obtained. Approaches to the derivatization of phenol and chlorine derivatives by azo coupling with 4-nitrophenyldiazonium and oxidative condensation with 4-aminoantipyrine for improving the sorption characteristics of the studied phenols are proposed. The efficiency of the two derivatization methods is compared. The sorption kinetics of phenol and 2-chlorophenol derivatives and the effect of pH on the nature of their sorption are studied. The features of the sorption of phenol derivatives on nonwoven materials and the corresponding sorption isotherms are interpreted. Examples of the quantitative assessment of the concentration of phenols in aqueous media by the mathematical processing of digital images of the colored areas of test tools are presented. It is shown that the proposed methods can be used for the determination of phenol and 2-chlorophenol with the preconcentration of their derivatives on a PA-6 nanofiber in the range 0.2–1.0 μM (≈0.02–0.09 mg/L for phenol, ≈0.03–0.13 mg/L for 2-chlorophenol) with an error of colorimetric determination of no more than 20% (MAChshld phenol is 0.001 mg/L for the amount of volatile phenols in water bodies, provided that water is disinfected with chlorine; in other cases, the MAC is 0.1 mg/L).

Impact of Smoke from Wheat, Oat, and Clover Stubble Burning on Cabernet Sauvignon Grapes and Wine

Background and Aims. Stubble burning is an agricultural practice employed by some grain growers to prepare farmland for sowing and/or to control weeds and pests. Grapegrowers and winemakers have questioned whether the resulting smoke can contaminate grapes in nearby vineyards. This study therefore sought to determine the potential for smoke from three different stubble burns to taint grapes and wine. Methods and Results. Excised bunches of mature Cabernet Sauvignon grapes were exposed to smoke from prescribed burning of wheat, oat, and Balansa clover stubble windrows. Environmental sensors monitored the concentration of particulate matter as a measure of smoke density, while chemical and sensory analysis established the extent to which grapes and wine were tainted by smoke. Only grapes that were positioned among the burning wheat windrows or downwind, but in close proximity (∼200 m) to the oat stubble burn, were exposed to sufficient quantities of smoke to result in a detectable concentration of volatile phenols (up to 12 µg/kg), as chemical markers of smoke taint. These grapes yielded wines with two to threefold higher volatile phenol concentrations (up to 18 µg/L) than other wines, including the control wine, and low intensity, but perceptible smoke-related sensory attributes, indicative of low-level smoke taint. Conclusions. Chemical and sensory analyses suggest the risk of smoke taint from stubble burning is low, except where vineyards are immediately downwind and/or prolonged or repeated smoke exposure occurs. However, stubble moisture content and prevailing weather conditions affect smoke density and dispersion, and will therefore affect the potential for smoke contamination by grapes. Significance of the Study. This study will assist colocated grain growers and grape and wine producers to undertake commercial operations, without negatively impacting one another.

Development of a molecular diagnostic test for the specific detection of Brettanomyces bruxellensis in red wine

Brettanomyces bruxellensis is considered the main source of spoilage in red wine. This yeast, by producing volatile phenols, is responsible for the development of unpleasant aromas affecting the quality of final products and resulting in substantial economic losses for wine producers. This work therefore describes the development of an easy to-use colorimetric molecular diagnostic test for the rapid and specific detection of B. bruxellensis in wine. Detection was achieved using a sandwich hybridization format in which the target RNA was recognized by an immobilized DNA capture probe and a labelled DNA signal probe. The proposed device was highly specific to B. bruxellensis and showed a linear relationship between measured signal and target RNA concentration in the range 0.1–5 ng μL−1, with a limit of detection value of 0.1 ng μL−1 of total RNA. The colorimetric assay was validated on red wine samples, with a detection limit of 102 CFU mL−1. This study suggests that the reported method could be used for early detection of spoilage yeasts in wine and other alcoholic beverages.

Contaminated Perry in Patagonia Argentina: A Case Study.

Perry is a beverage obtained by fermentation of pear juice, popular in the North Hemisphere. In Argentina it is an emerging market, particularly in the Patagonian region. The aim of this work is to describe and to evaluate the spoilage yeasts associated to six perry samples showing signs of microbiological contamination from a local craft perry company in North Patagonian region. Eighteen yeasts were isolated from four of the six perry samples where Brettanomyces custersianus, Brettanomyces bruxellensis and Zygosaccharomyces parabailii were identified. The growth capacity of these isolates in the presence of antimicrobial agents (sulfite and potassium sorbate) was analyzed in solid media. Growth parameters in sterile perry must was evaluated and the production of undesirable compounds were evaluated, products were characterized in terms of their aromatic and physicochemical features. The yeasts Z. parabailii NPCC1791 was able to grow on plates containing sulfite concentrations of up to 4mM and produced high methanol concentrations in perry. Additionally, B. bruxellensis NPPC1792 was able to produce methanol as well as high concentrations of volatile phenols including 4-ethylphenol and 4-ethylguaiacol. These results demonstrate the potential of these species as perry contaminants. Given the lack of studies describing the contaminating yeasts in perry production, this work represents the first report about perry spoilage yeasts in Argentina, with this knowledge, control strategies can be developed to prevent microbiological contamination and minimize product loss.

Role of p-Coumaric Acid and Micronutrients in Sulfur Dioxide Tolerance in Brettanomyces bruxellensis

Role of p-Coumaric Acid and Micronutrients in Sulfur Dioxide Tolerance in Brettanomyces bruxellensis

Cloning and characterization of phenolic acid decarboxylase responsible for aromatic volatile phenols production in Paocai based on metatranscriptomics

Sichuan Paocai is a kind of fermented vegetable with rich microorganism and enzyme resources. Based on our previous metatranscriptomics and flavor-oriented metabolomics studies, three potential phenolic acid decarboxylases LvPAD, DhFDC1 and LvUbiD were mined from environmental RNA of industrial Sichuan Paocai, and their catalytic function were verified by heterologous expression. LvPAD, which was derived from Lactobacillus vermolensis and had the highest catalytic activity among the three enzymes, was selected for further purification and characterization. It was optimally active at pH 6.0 and 35 °C, had good thermal stability and pH tolerance, and did not require specific cofactors. Kinetic parameters showed that LvPAD could catalyze the decarboxylation of p-coumaric acid, ferulic acid and caffeic acid with the kcat/Km values of 460.6 ± 0.1, 23.7 ± 0.09 and 118.2 ± 0.1 mM−1 s−1, respectively, and the products of the first two substrates were 4-vinylphenol and 4-vinylguaiacol with aromatic characteristics. Moreover, LvPAD was successfully used to preliminarily strengthen the vinylphenol aroma of industrial Paocai, which could shorten the fermentation time to a certain extent in practical production. Therefore, this work not only validated the important role of LvPAD in the production of aromatic phenols in Paocai, but also facilitated the mining of more enzymes from Paocai to improve the flavor and production process in the future.

Correlation Between the Diversity Characteristics of Groundwater Bacterial Community and Environmental Factors in Typical Industrial Areas

In order to investigate the composition and diversity of groundwater bacterial communities in typical industrial areas in Shanghai, the Illumina MiSeq high-throughput technology was adopted to explore the correlation and response mechanism of groundwater bacterial communities and environmental factors in typical industries, combined with the analysis of groundwater tri-nitrogen, heavy metals, organic matter, and other indicators. The results showed that the ammonia nitrogen in the groundwater of the petrochemical industry was 64.49%, 32.46%, and 113.91% higher than that of the textile industry, metal products industry, and other industries (P<0.05), respectively. The main detectable indicators of organic matter were total petroleum hydrocarbons (TPH) and volatile phenol. The mass concentration of volatile phenol in groundwater of the petrochemical industry was significantly higher than that of the textile industry, metal products industry, and other industries (P<0.05). The mass concentration of arsenic in the metal products industry was 49.26% and 50.59% higher than that in the petrochemical industry and other industries (P<0.05), respectively. Chloride, manganese, sulfate, etc., were significantly different in different industries (P<0.05). The Shannon index of groundwater in the textile industry was the highest at 3.14, whereas the Shannon index and Ace index of the groundwater in the metal products industry were as low as at 2.42 and 960.46, respectively. The dominant bacterial phylum in groundwater in the industrial area was Proteobacteria, accounting for 80.05%-86.18%. Arsenic, mercury, TPH, etc. were the main influencing factors in groundwater in industrial areas, whereas the nitrifying bacteria, denitrifying bacteria, and organic matter-degrading bacteria were mostly related to groundwater environmental factors. The results of this study can provide theoretical support for groundwater pollution risk management and microbial remediation in petrochemical and metal product industrial areas.

Rapid headspace solid-phase microextraction sheets with direct analysis in real time mass spectrometry (SPMESH-DART-MS) of derivatized volatile phenols in grape juices and wines

Volatile phenols possess “smoky, spicy” aromas and are routinely measured in grapes, wines and other foodstuffs for quality control. Routine analyses of volatile phenols rely on gas chromatography – mass spectrometry (GC-MS), but slow throughput of GC-MS can cause challenges during times of surge demand, i.e. following ‘smoke taint’ events involving forest fires near vineyards. Parallel extraction of headspace volatiles onto sorbent sheets (HS-SPMESH) followed by direct analysis in real time mass spectrometry (DART-MS) is a rapid alternative to conventional GC-MS approaches. However, HS-SPMESH extraction is poorly suited for lower volatility odorants, including volatile phenols. This work reports development and validation of an HS-SPMESH-DART-MS approach for five volatile phenols (4-ethylphenol, 4-ethylguiacol, guaiacol, 4-methylguaiacol, and cresols). Prior to HS-SPMESH extraction, volatile phenols were acetylated to facilitate their extraction. A unique feature of this work was the use of d6-Ac2O as a derivatizing agent to overcome issues with isobaric interferences inherent to chromatography-free MS techniques. The use of alkaline conditions during derivatization resulted in cumulative measurement of both free and bound forms of volatile phenols. The validated HS-SPMESH-DART-MS method achieved a throughput of 24 samples in ∼60 min (including derivatization and extraction time) with low limits of detection (<1 μg L−1) and good repeatability (3–6% RSD) in grape and wine matrices. Validation experiments with smoke-tainted grape samples indicated good correlation between total (free + bound) volatile phenols measured by HS-SPMESH-DART-MS and a gold standard GC-MS method.