Influence of ripeness and maceration of the grapes on levels of furan and carbonyl compounds in wine - Simultaneous quantitative determination and assessment of the exposure risk to these compounds

Flavor characteristics of Shanlan rice wines fermented for different time based on HS-SPME-GC-MS-O, HS-GC-IMS, and electronic sensory analyses

Flavor characteristics of Shanlan rice wines with different fermentation time were analyzed. Results suggested that 3-methyl-1-butanol, phenylethyl alcohol, ethyl acetate, and diethyl succinate were the characteristic volatiles of Shanlan rice wine by using headspace solid-phase microextraction-gas chromatography-mass spectrometry-olfactometry. The most varieties (38) of volatiles appeared at a 3-year-fermentation time, contributing a unique and harmonious aroma to the Shanlan rice wine fermented for 3 years, but only 19 types were observed at 45-days and 1-year fermentation times. A similar trend was intuitively visible in the headspace-gas chromatography-ion mobility spectrometry analysis. The Shanlan rice wine fermented for 3 years had a similar taste profile to that fermented for 45 days, but with distinguishing contents of free amino acids (1352.80 mg/L and 2261.50 mg/L, respectively) and organic acids (9.58 g/L and 49.88 g/L, respectively). The Shanlan rice wine fermented for 1 year had a strong taste with more intensity of most taste attributes.

Research progress on the application of different controlling strategies to minimizing ethyl carbamate in grape wine

Ethyl carbamate (EC) is a probable carcinogenic compound commonly found in fermented foods and alcoholic beverages and has been classified as a category 2A carcinogen by the International Agency for Research on Cancer (IARC). Alcoholic beverages are one of the main sources of EC intake by humans. Therefore, many countries have introduced a standard EC limit in alcoholic beverages. Wine is the second largest alcoholic beverage in the world after beer and is loved by consumers for its rich taste. However, different survey results showed that the detection rate of EC in wine was almost 100%, while the maximum content was as high as 100 μg/L, necessitating EC content regulation in wine. The existing methods for controlling the EC level in wine mainly include optimizing raw fermentation materials and processes, using genetically engineered strains, and enzymatic methods (urease or urethanase). This review focused on introducing and comparing the advantages, disadvantages, and applicability of methods for controlling EC, and proposes two possible new techniques, that is, changing the fermentation strain and exogenously adding phenolic compounds. In the future, it is hoped that the feasibility of this prospect will be verified by pilot-scale or large-scale application to provide new insight into the regulation of EC during wine production. The formation mechanism and influencing factors of EC in wine were also introduced and the analytical methods of EC were summarized.

A comprehensive review of furan in foods: From dietary exposures and in vivo metabolism to mitigation measures

Furan is a thermal food processing contaminant that is ubiquitous in various food products such as coffee, canned and jarred foods, and cereals. A comprehensive summary of research progress on furan is presented in this review, including discussion of (i) formation pathways, (ii) occurrence and dietary exposures, (iii) analytical techniques, (iv) toxicities, (v) metabolism and metabolites, (vi) risk assessment, (vii) potential biomarkers, and (viii) mitigation measures. Dietary exposure to furan varies among different countries and age groups. Furan acts through various toxicological pathways mediated by its primary metabolite, cis-2-butene-1,4-dial (BDA). BDA can readily react with glutathione, amino acids, biogenic amines, or nucleotides to form corresponding metabolites, some of which have been proposed as potential biomarkers of exposure to furan. Present risk assessment of furan mainly employed the margin of exposure approach. Given the widespread occurrence of furan in foods and its harmful health effects, mitigating furan levels in foods or exploring potential dietary supplements to protect against furan toxicity is necessary for the benefit of food safety and public health.

Development of a Rapid and Sensitive Fluorescence Sensing Method for the Detection of Acetaldehyde in Alcoholic Beverages

Acetaldehyde is regarded as an important flavor compound in alcoholic beverages. With the advantages of rapidity, low cost and high sensitivity, fluorescent probe could be used as a new tool for the detection of acetaldehyde. Here, an effective fluorescence sensing method based on fluorescent probe N1 (FPN1) was established in this study. The function of FPN1 relies on the nucleophile substitution reaction and photoinduced electron transfer (PET), resulting in a fluorescence increase. Remarkably, the pretreatment background removal method (BRM) was successfully applied for removal of the interference of pyruvate and acetal. The linearity range (LR), limit of detection (LOD) and recovery of the fluorescence sensing method with BRM were 0.0053–200 mg/L, 0.0016 mg/L and 94.02–108.12%, respectively, which showed a broader detection range and better performance on sensitivity compared with the traditional quantitation using gas chromatography (GC). Furthermore, successful application of the method in real samples indicated the advantages of low-cost and rapidity for small-scale detection while assuring the accuracy, which provides a new strategy for the detection of acetaldehyde concentration in alcoholic beverages.

Construction of a Turn-off-on Fluorescent System Based On Aggregation Induced Emission of Acetaldehyde Using Carbonized Polymer dots and Tb3

It was the first time to report the aggregation induced emission (AIE) of acetaldehyde (AA) on the surface of carbonized polymer dots (CPDs) with the auxiliary of Tb³⁺. Based on the AIE of AA, a turn-off-on fluorescence method was established for AA detection using the porous CPDs-Tb³⁺ system. The one-pot hydrothermal method was used to obtain CPDs, using milk and polyethyleneimine (PEI) as precursors. In the presence of Tb³⁺, CPDs aggregated immediately and even forming precipitate, and the fluorescence intensity decreased obviously. AA can effectively embed on the surface of CPDs-Tb³⁺ due to the porous structure. AA displayed obviously blue fluorescence with excitation wavelength at 370 nm (emission peak at 460 nm), while there was no fluorescence peak when excited at 460 nm. In the CPDs-Tb³⁺ solution, AA exhibits obvious fluorescence enhancement effect (λ_ex 460 nm, λ_em 545 nm). And then, AA can be determined by the turn-off-on system based on the linear relationship between fluorescence enhancement and the concentration of AA ranging from 0.04 mM to 42.48 mM. The limit of detection (LOD) was 0.02 mM. The turn-off-on system was successfully applied to determine AA in wine samples. The strategy may be exploited to monitor AA in more drinking or foodstuff samples.

Occurrence of Ethyl Carbamate in Foods and Beverages: Review of the Formation Mechanisms, Advances in Analytical Methods, and Mitigation Strategies

ABSTRACT

Ethyl carbamate (EC) is a process contaminant that can be formed as a by-product during fermentation and processing of foods and beverages. Elevated EC concentrations are primarily associated with distilled spirits, but this compound has also been found at lower concentrations in foods and beverages, including breads, soy sauce, and wine. Evidence from animal studies suggests that EC is a probable human carcinogen. Consequently, several governmental institutions have established allowable limits for EC in the food supply. This review includes EC formation mechanisms, occurrence of EC in the food supply, and EC dietary exposure assessments. Current analytical methods used to detect EC will be covered, in addition to emerging technologies, such as nanosensors and surface-enhanced Raman spectroscopy. Various mitigation methods have been used to maintain EC concentrations below allowable limits, including distillation, enzymatic treatments, and genetic engineering of yeast. More research in this field is needed to refine mitigation strategies and develop methods to rapidly detect EC in the food supply.

HIGHLIGHTS

Inhibitory Effect on Acrolein by Cyanidin-3-O-glucoside and Its Acrolein Adducts from the Pigment of Mynica Red

Acrolein (ACR), the simplest α,β-unsaturated aldehyde, possesses high reactivity and toxicity both in vitro and in vivo and results in various chronic diseases. This has attracted increasing interest from researchers to screen various bioactive compounds to control it. In this article, we attempted to discover a new attribute of cyanidin-3-O-glucoside (C3G), including its ACR-scavenging capacity, reaction pathway, and possible application. Our findings revealed that C3G could capture ACR to form mono- and diadducts at room temperature by using liquid chromatography-mass spectrometry, and we further synthesized and elucidated the structures of C3G-ACR and C3G-2ACR using HRMS and 2D NMR. The structural data validated that there were two active sites of C3G for trapping ACR: at C-6 in the A-ring and C-5' in the B-ring. In addition, we found that C3G-ACR exhibited a more remarkable clearing ability than C3G within a short time. More than 65.9% of ACR was eliminated by C3G-ACR within 5 min via further formation of C3G-2ACR, but there was no obvious effect of C3G on ACR. When the incubation time was extended to 120 min, C3G could remove up to 83.2% of ACR. Subsequently, we also observed that mynica red (>5% C3G), as a pigmented food additive, could efficiently eliminate ACR generated in the Chinese liquor model and real red bayberry wine products to form C3G-ACR and C3G-2ACR. Both adducts increased significantly, by 10 times to a 100 times, after adding mynica red to red bayberry wine products for 24 h; they also increased rapidly with prolonged incubation time in the liquor-mynica red model system. Therefore, our findings suggest that C3G or mynica red may be developed as a promising novel ACR inhibitor in fruit wine and assembled alcoholic drinks or as a health food.

Origin, Succession, and Control of Biotoxin in Wine

Wine is a worldwide alcoholic beverage with antioxidant active substances and complex flavors. Moderate drinking of wine has been proven to be beneficial to health. However, wine has some negative components, such as residual pesticides, heavy metals, and biotoxins. Of these, biotoxins from microorganisms were characterized as the most important toxins in wine. Wine fermentation mainly involves alcoholic fermentation, malolactic fermentation, and aging, which endue wine with complex flavors and even produce some undesirable metabolites. These metabolites cause potential safety risks that are not thoroughly understood. This review aimed to investigate the origin, evolution, and control technology of undesirable metabolites (e.g., ochratoxin A, ethyl carbamate, and biogenic amines) in wine. It also highlighted current wine industry practices of minimizing the number of biotoxins in wine.

An insight into volatile and non-volatile compounds of Chinese horsebean-chili-paste meju produced by natural brewing and temperature-controlled brewing methods

BACKGROUND

Chinese horsebean-chili-paste (CHCP) is a traditional fermented condiment in China, known as 'the soul of Sichuan cuisine'. The horsebean-to-meju phase in its preparation is important for CHCP production and contributes significantly to its taste and odor. In this study, a comprehensive flavor compound profiling analysis of the naturally brewed horsebean meju (NBHM) and the temperature-controlled brewed horsebean meju (TCBHM) was performed with two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS), and the analysis of physicochemical characteristics and free amino acids. Their aroma-active components and characteristic flavor compounds were evaluated. The flavor compounds responsible for differentiating NBHM and TCBHM were also determined based on the Fisher ratio and principal component analysis.

RESULTS

The pH and the reducing sugar and amino-acid nitrogen content of NBHM were 5.38, 64.43, and 5.76 g kg^-1 , respectively, whereas those of TCBHM were 5.13, 29.20, and 7.43 g kg^-1 . A total of 356 volatiles were identified from 2571 compounds, and 257 volatile compounds were identified in NBHM compared to 322 volatiles in TCBHM. These two horsebean mejus (HMs) exhibited a similar proportion profile for 30 aroma-active compounds. Benzoic acid ethyl ester, 4-ethyl-2-methoxy-phenol and argnine were determined to be characteristic flavor components for NBHM, while 1-(2-furanyl)-ethanone, 2,6-dimethyl-pyrazine, threonine, valine and tyrosine were specific to TCBHM.

CONCLUSION

Temperature-controlled brewed horsebean meju possessed better physicochemical and flavor characteristics than NBHM. The temperature-controlled brewing technique in CHCP production can be used as a promising alternative to the traditional natural brewing method. © 2020 Society of Chemical Industry.

An overview of chemical contaminants and other undesirable chemicals in alcoholic beverages and strategies for analysis

The presence of chemical contaminant in alcoholic beverages is a widespread and notable problem with potential implications for human health. With the complexity and wide variation in the raw materials, production processes, and contact materials involved, there are a multitude of opportunities for a diverse host of undesirable compounds to make their way into the final product-some of which may currently remain unidentified and undetected. This review provides an overview of the notable contaminants (including pesticides, environmental contaminants, mycotoxins, process-induced contaminants, residues of food contact material [FCM], and illegal additives) that have been detected in alcoholic products thus far based on prior reviews and findings in the literature, and will additionally consider the potential sources for contamination, and finally discuss and identify gaps in current analytical strategies. The findings of this review highlight a need for further investigation into unwanted substances in alcoholic beverages, particularly concerning chemical migrants from FCMs, as well as a need for comprehensive nontargeted analytical techniques capable of determining unanticipated contaminants.

Role of gas chromatography and olfactometry to understand the wine aroma: Achievements denoted by multidimensional analysis

The human nose has been used as a detector in gas chromatography analysis to evaluate odoriferous compounds related to aroma and quality of wine. Several olfactometric techniques are available to access the description, intensity, and/or duration of the odor of each compound. Olfactometry can be associated with one-dimensional gas chromatography or multidimensional gas chromatography, including heart-cut gas chromatography and comprehensive two-dimensional gas chromatography. Multidimensional gas chromatography may help to resolve coeluted compounds and detect important trace components for the aroma. The identification of odor-active compounds may help to differentiate wines according to terroir, grapes cultivars used in winemaking or types of aging, understand the role of fungal infection of grapes for wine quality, find the best management practices in vineyard and vinification to obtain the greatest quality. In addition, when the instrumental techniques are combined with sensory analysis, even more accurate information may be obtained regarding the overall wine aroma. This review discloses the state of the art of olfactometric methods and the analytical techniques used to investigate odor-active compounds such as one-dimensional gas chromatography, multidimensional gas chromatography, and comprehensive two-dimensional gas chromatography. The advances in knowledge of wine aroma achieved with the use of these techniques in the target and profiling approaches were also discussed.

Quantitative Determination of Acrolein in Cider by 1H NMR Spectrometry

Acrolein occasionally appears in cider, completely spoiling its quality due to its bitter taste. It is crucial to detect it in the early steps, before the taste is severely affected, to apply the appropriate treatment. A simple and rapid analytical method to determine this compound in cider is therefore desirable. In this work, a quantitative determination method of acrolein in cider is proposed using the proton nuclear magnetic resonance technique (¹H NMR). Acrolein produces a doublet signal in the spectrum at 9.49 ppm, whose area is used to determine the concentration of this compound. 3-(trimethylsilyl)-2,2,3,3-d⁴-propionic acid sodium salt is added to the cider as a reference for 0.00 ppm and 1,3,5-benzenetricarboxylic acid as an internal standard for acrolein determination. The method is validated by gas chromatography (GC). There is a good correlation between the acrolein concentrations obtained by ¹H NMR and by gas chromatography in different commercial ciders (Pearson coefficient 0.9994). The 95% confidence interval for the intercept is 0.15 ± 0.49 (includes 0) and for the slope is 0.98 ± 0.03 (includes 1). When applying the paired t test, no significant difference is observed. The proposed method is direct, and no prior derivatization is needed.

Modulating Wine Pleasantness Throughout Wine-Yeast Co-Inoculation or Sequential Inoculation

Wine sensory experience includes flavor, aroma, color, and (for some) even acoustic traits, which impact consumer acceptance. The quality of the wine can be negatively impacted by the presence of off-flavors and aromas, or dubious colors, or sediments present in the bottle or glass, after pouring (coloring matter that precipitates or calcium bitartrate crystals). Flavor profiles of wines are the result of a vast number of variations in vineyard and winery production, including grape selection, winemaker’s knowledge and technique, and tools used to produce wines with a specific flavor. Wine color, besides being provided by the grape varieties, can also be manipulated during the winemaking. One of the most important “tools” for modulating flavor and color in wines is the choice of the yeasts. During alcoholic fermentation, the wine yeasts extract and metabolize compounds from the grape must by modifying grape-derived molecules, producing flavor-active compounds, and promoting the formation of stable pigments by the production and release of fermentative metabolites that affect the formation of vitisin A and B type pyranoanthocyanins. This review covers the role of Saccharomyces and non-Saccharomyces yeasts, as well as lactic acid bacteria, on the perceived flavor and color of wines and the choice that winemakers can make by choosing to perform co-inoculation or sequential inoculation, a choice that will help them to achieve the best performance in enhancing these wine sensory qualities, avoiding spoilage and the production of defective flavor or color compounds.

Validation of an analytical method using HS-SPME-GC/MS-SIM to assess the exposure risk to carbonyl compounds and furan derivatives through beer consumption

Compounds with toxic potential may occur in beer, such as carbonyl compounds (acetaldehyde, acrolein, ethyl carbamate [EC] and formaldehyde) and furan derivatives [furfural and furfuryl alcohol (FA)]. The objective of this study was, for the first time, to validate a method based on headspace-solid phase microextraction using a PDMS-overcoated fibre and gas chromatography with mass spectrometric detection in selected ion monitoring mode (HS-SPME-GC/MS-SIM) to investigate target carbonyl compounds and furan derivatives in beers. Analytical curves showed proper linearity with r² ranging from 0.9731 to 0.9960 for acetaldehyde and EC, respectively. The lowest LOD was found for acetaldehyde (0.03 µg L^-1), while the lowest LOQ value (1.0 µg L^-1) was found for acetaldehyde and EC, formaldehyde and furfural. Recovery (90% to 105%), intermediate precision and repeatability (lower than 13%), limits of detection and quantification (values below 2.5 μg L^-1) showed that the method is suitable to simultaneously quantify these compounds. EC was detected in only two samples (1 lager and 1 ale). Furfural was found in 37% and 82% of ale and lager beers, respectively. Acetaldehyde, acrolein, formaldehyde and FA were detected in all samples. However, acrolein was the only compound found in the commercial samples at a concentration capable of causing health risk. Besides furfural and FA, four other furan-containing compounds (5-methyl-2-furan methanethiol, acetylfuran, 5-methylfurfural and γ-nonalactone) were also found in beers, however, at levels low enough not to impose potential health risk.

Carbonyl compounds in different stages of vinification and exposure risk assessment through Merlot wine consumption

The objective of this research was to estimate for the first time the transformations that the free form of some target carbonyl compounds may undergo during winemaking and assess the exposure risk to these compounds through the consumption of the Merlot commercial wines under study. Acrolein and furfural were found in grapes and the respective wines, although levels were observed to decline throughout the winemaking process. Formaldehyde was found in all stages of wine production in levels lower than the limit of quantification of the method and ethyl carbamate was not found in samples. Acetaldehyde seems to be a precursor of acetoin and 2,3-butanediol, since the levels of this aldehyde decreased along winemaking and the formation of the ester and alcohol was verified. Furfural levels decreased, while the occurrence of furan-containing compounds increased during winemaking. The formation of acetaldehyde during alcoholic fermentation and the potential environmental contamination of grapes with acrolein and furfural are considered as the critical points related to the presence of toxic carbonyl compounds in the wine. Acrolein was found in the samples under study in sufficient quantities to present risk to human health, while other potentially toxic carbonyl compounds did not result in risk. This study indicated for the first time the presence of acrolein in grapes suggesting that environmental pollution can play an important role in the levels of this aldehyde detected in wines. Reduction of the emission of this aldehyde to the environment may be achieved by replacing wood burning by another heat source in fireplaces or wood stones, and abandoning the practice of burning garbage and vegetation.

Opportunities for green microextractions in comprehensive two-dimensional gas chromatography / mass spectrometry-based metabolomics - A review

Microextractions have become an attractive class of techniques for metabolomics. The most popular technique is solid-phase microextraction that revolutionized the field of modern sample preparation in the early nineties. Ever since this milestone, microextractions have taken on many principles and formats comprising droplets, fibers, membranes, needles, and blades. Sampling devices may be customized to impart exhaustive or equilibrium-based characteristics to the extraction method. Equilibrium-based approaches may rely on additional methods for calibration, such as diffusion-based or on-fiber kinetic calibration to improve bioanalysis. In addition, microextraction-based methods may enable minimally invasive sampling protocols and measure the average free concentration of analytes in heterogeneous multiphasic biological systems. On-fiber derivatization has evidenced new opportunities for targeted and untargeted analysis in metabolomics. All these advantages have highlighted the potential of microextraction techniques for in vivo and on-site sampling and sample preparation, while many opportunities are still available for laboratory protocols. In this review, we outline and discuss some of the most recent applications using microextractions techniques for comprehensive two-dimensional gas chromatography-based metabolomics, including potential research opportunities.

D-A type sensor array for differentiation and identification of white wine varieties based on specific solvent effect activated by CT-LE transition

In this work, we synthesize a series of compounds with electron donor (D) and acceptor (A) units. They show general solvent effect in aprotic solvents, suggesting a charge transfer (CT) process. While in protic solvents including water, ethanol and methanol, the spectra exert no polarity-dependence but a remarkable hypochromatic shift together with the fading of CT band. Dynamic analysis implies that intermolecular hydrogen bond will be formed between carboxylic acid and protic solvent, boosting another deactivation pathway that jumps off a bigger energy gap, in other words, favoring the locally excited (LE) state emission. The CT-LE transition involves variations in both absorption and emission spectra, and further poses competition with other mechanisms including activated/restricted intramolecular rotation (IR/RIR). Inspired by the cross-reactivity, we turn our attention to the development of sensor array, in order to identify white wine varieties. The differential spectral responses are recorded, generating multiple factors including absorption wavelength (λ_ab), emission wavelength (λ_em), absorbance (Abs.) and emission intensity (Int.). These factors are processed with principal component analysis (PCA), creating a three-dimensional fingerprint data base for white wines. The data points in the coordinate system are clustered into 10 different groups, demonstrating a clear differentiation of all the white wines. More importantly, as our final test for whether the sensor array can identify the counterfeits, an adulterated liquor sample, which is provided by police officers, is fingerprinted on the three-dimensional diagram. Its canonical factors fall into an area distinct from the adulterated wine, indicating a clear identification.

Effects of Schiff Base Formation and Aldol Condensation on the Determination of Aldehydes in Rice Wine Using GC-MS

The Schiff base reaction and aldol condensation that occur during sample preparation can lead to the reduction of aldehyde content in the analysis of traditional Korean rice wine, makgeolli. The contents of aldehydes were decreased, whereas those of hydroxy carbonyl compounds were increased by increasing the pH. In the presence of added amino acids, the levels of aldehydes in makgeolli were reduced as the amount of the amino acid alanine increased. Also, the contents of hydroxyl carbonyl compounds were reduced by alanine addition as compared to the control. Therefore, the determination of aldehydes can be affected by pH and the amount of amino acids, which can vary during fermentation and storage of alcoholic beverages because pH and amino acids affect Schiff base formation and aldol condensation.