An Efficient Assay for Simultaneous Quantification of Ethyl Carbamate and Phthalate Esters in Chinese Liquor by Gas Chromatography-Mass Spectrometry

Extraction and analytical approaches for the determination of post-food processing major carcinogens: A comprehensive review towards healthier processed food

Different food processing methods, e.g. fermentation, grilling, frying, etc., to improve food sensory attributes or shelf-stability are typically employed in different cuisines worldwide. These methods may illicit in-situ health-hazardous chemicals via thermal or enzymatic-mediated processes or chemical interactions with food preservatives. This review provides a comparative overview of the occurrence, extraction, and determination of the major food carcinogens such as nitrosamines (NAs), biogenic amines (BAs), heterocyclic aromatic amines (HAAs), polycyclic aromatic hydrocarbons (PAHs), ethyl carbamate (EC), and malondialdehyde (MDA). Their carcinogenicity levels vary from group 1 (carcinogenic to humans) e.g. benzo[a]pyrene, group 2A (probably carcinogenic to humans) e.g. N-nitrosodiethylamine, group 2B (possibly carcinogenic to humans) e.g. chrysene or group 3 (non-classifiable as carcinogenic to humans) e.g. MDA. Chromatography-based methods are the most predominant techniques used for their analysis. LC-MS is widely used for both volatile/non-volatile NAs, HAAs, BAs, and EC, whereas GC-MS is applied more for volatile NAs, PAHs and MDA.

Rapid measurement of ethyl carbamate in Chinese liquor by fast gas chromatography photoionization-induced chemical ionization mass spectrometry

As a common by-product during the production of alcoholic beverages, such as Chinese liquor, ethyl carbamate (EC) poses potential genotoxicity and is associated with the risk of various cancers. Hence, rapidly and accurately measuring the content of EC in liquor is critical to assess the product quality and risks of mass samples during the production process. In this study, a feasible method based on fast gas chromatography photoionization-induced chemical ionization mass spectrometry (FastGC-PICI-TOFMS) was developed for the analysis of EC in Chinese liquor. The rapid separation of EC in Chinese liquor was conducted using FastGC based on a thermostatic column set at 150 °C to eliminate the interferences of matrix effects. The PICI-TOFMS could realize accurate quantification of EC without any sample pre-treatment due to the efficient ionization of EC by the PICI source. As a result, the total analysis time for EC in Chinese liquor was less than 4 min. The limit of detection (LOD) for EC was 4.4 μg L-1. And the intra-day and inter-day precision were 3.2%-3.7 % and 1.6 %, respectively. Finally, the ability of the proposed method was preliminarily proved by high-throughput and accurate measurement of EC in four different flavors of Chinese liquors.

A Straightforward, Sensitive, and Reliable Strategy for Ethyl Carbamate Detection in By-Products from Baijiu Production by Enzyme-Linked Immunosorbent Assay

Baijiu is a renowned Chinese distilled liquor, notable for its distinctive flavor profile and intricate production process, which prominently involves fermentation and distillation. Ethyl carbamate (EC), a probable human carcinogen, can be potentially formed during these procedures, thus prompting significant health concerns. Consequently, the contamination of EC during Baijiu production has become an increasingly pressing issue. In this study, we developed a rapid and easily operable immunoassay for determining EC in the fermented materials used in Baijiu production. The development of a high-quality antibody specific to EC facilitated a streamlined analytical procedure and heightened method sensitivity. Furthermore, we systematically evaluated other essential parameters. Following optimization, the method achieved an IC50 value of 11.83 μg/kg, with negligible cross-reactivity against EC analogs. The recovery study demonstrated the method's good accuracy and precision, with mean recovery rates ranging from 86.0% to 105.5% and coefficients of variation all below 10%. To validate the feasibility of the technique, we collected and analyzed 39 samples simultaneously using both the proposed immunoassay and confirmatory gas chromatography-mass spectrometry (GC-MS). A robust correlation was observed between the results obtained from the two methods (R2 > 0.99). The detected EC levels ranged from 2.36 μg/kg to 7.08 μg/kg, indicating an increase during the fermentation process.

Rapid Determination of Ethyl Carbamate in Chinese Liquor via a Direct Injection Mass Spectrometry with Time-Resolved Flash-Thermal-Vaporization and Acetone-Assisted High-Pressure Photoionization Strategy

Ethyl carbamate (EC), a carcinogenic compound, is naturally produced in fermented foods and alcoholic beverages. Rapid and accurate measurement of EC is necessary and important for quality control and safety evaluation of Chinese liquor, a traditionally distilled spirit with the highest consumption in China, but it remains a great challenge. In this work, a direct injection mass spectrometry (DIMS) with time-resolved flash-thermal-vaporization (TRFTV) and acetone-assisted high-pressure photoionization (HPPI) strategy has been developed. EC was rapidly separated from the main matrix components, ethyl acetate (EA) and ethanol, by the TRFTV sampling strategy due to the retention time difference of these three compounds with large boiling point differences on the inner wall of a poly(tetrafluoroethylene) (PTFE) tube. Therefore, the matrix effect of EA and ethanol was effectively eliminated. The acetone-assisted HPPI source was developed for efficient ionization of EC through a photoionization-induced proton transfer reaction between EC molecules and protonated acetone ions. The accurate quantitative analysis of EC in liquor was achieved by introducing an internal standard method (ISM) using deuterated EC (d₅-EC). As a result, the limit of detection (LOD) for EC was 8.88 μg/L with the analysis time of only 2 min, and the recoveries ranged from 92.3 to 113.1%. Finally, the prominent capability of the developed system was demonstrated by rapid determination of trace EC in Chinese liquors with different flavor types, exhibiting wide potential applications in online quality control and safety evaluation of not only Chinese liquors but also other liquor and alcoholic beverages.

Simulation and Control of the Formation of Ethyl Carbamate during the Fermentation and Distillation Processes of Chinese Baijiu

Baijiu is a popular alcoholic beverage with a long history in China. However, the widespread presence of the ethyl carbamate (EC) carcinogen has raised many food safety concerns. To date, the main precursors of EC and its formation process have not been determined, resulting in difficulty controlling EC in Baijiu. In this study, the main precursors of EC are identified as urea and cyanide during the process of brewing for different flavors of Baijiu, while the dominant stage in which EC formation occurs is during the process of distillation rather than fermentation. In addition, the effects of temperature, pH value, alcohol concentration and metal ions on the formation of EC are confirmed. In the following study, the main precursor of EC is identified as cyanide during the process of distillation, and a combination of optimizing the distillation device and adding copper wire is proposed. Furthermore, the effect of this novel strategy is examined in gaseous reactions between cyanide and ethanol, reducing the concentration of EC by 74.0%. Finally, the feasibility of this strategy is verified in simulated distillations of fermented grains, reducing the formation of EC by 33.7-50.2%. This strategy has great application potential in industrial production.

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

Ethyl carbamate in Chinese liquor (Baijiu): presence, analysis, formation, and control

Ethyl carbamate (EC) is a genotoxic and carcinogenic compound that is also a by-product of fermented foods (bread, sour milk, soy cheese, etc.) and alcoholic beverages (wine, sake, distilled liquor, etc.). Studies have showed that ethyl carbamate is ingested by humans primarily through the consumption of alcoholic beverages. Many countries have thus established EC limits for alcoholic beverages. Chinese liquor (Baijiu) is a traditional and unique distilled liquor, which has a huge consumption in China due to its excellent color, flavor, and taste. Therefore, the control of EC in Chinese liquor is of great significance. This review summarized for the first time the progress in presence level, analysis method, formation mechanism, and elimination strategy of EC of Chinese liquor in recent decades. KEY POINTS: • GC-MS and HPLC are the main methods to quantify EC in Chinese liquor. • EC is formed in the fermentation, distillation, and storage stage. • EC content can be reduced from raw material, microorganism, and production process.

Directional design of a starter to assemble the initial microbial fermentation community of baijiu

Tetramethylpyrazine (TTMP) is an important aroma compound in the sesame-flavored Chinese liquor, baijiu. Similar to other traditional spontaneously fermented foods, it is difficult to directionally increase the key aroma compound in situ fermentation system of baijiu without changing its sensory profile. The assembly of the starting microbial community for fermentation by using a functional starter provides a promising solution which needs careful manipulations. This study aimed to increase TTMP concentration in baijiu using the functional starter inoculated with the indigenous strain B. amyloliquefaciens XJB-104 with high TTMP production ability. After inoculation, the relative abundance of Bacillus in the initial stage of fermentation increased from 82.14% to 88.47%. The TTMP concentration increased by about 26 and 24-fold in the fermented grains (zaopei) and baijiu respectively compared with controls. Moreover, the quality of baijiu was improved according to sensory analyses. In addition, correlation analysis confirmed that the increased TTMP content in baijiu was due to the successful assembly of the initial fermentation microbiota after the inoculation of B. amyloliquefaciens.

The importance of higher alcohols and esters for sensory evaluation of rheinriesling and chardonnay wine varieties

For a consumer, one of the first characters for evaluation of wine is its scent. A pleasant aroma of wine associated with the subsequent taste experience can be remembered by the consumer for a long time and appreciated appropriately. For this reason, the aromatic properties of wine are very important to both consumers and producers. The question, however, is to assess the evaluation of wine sensory evaluation based on a rapidly developing chemical analysis without the use of a panel of evaluators. This study has dealt with the problem of the correlation of sensory evaluation of wine with the total content of higher alcohols and esters in wine prepared from the same wine varieties (Rheinriesling and Chardonnay) on the same vineyard under the same climatic conditions and processed using the same production technology in the years 2008 - 2012. The total content of higher alcohols and esters was determined by gas chromatography with a mass spectrometer (GC/MS). The correlation between the sensory evaluation and the total content of higher alcohols has not been established. However, the direct effect of the total content of the esters on the level of the sensory analysis of the two varieties studied was demonstrated. This can be an important economic indicator for a manufacturer who can estimate the sensory quality of the wine only on the basis of chemical analysis and thus estimate the success of the wine on the consumer market.