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Ethyl carbamate was quantified in cachaca using high-performance liquid chromatography with fluorescence detection during the production process and during storage in different types of wooden casks and glass containers, with and without the presence of light. According to the physicochemical analysis, the head and tail fractions are unacceptable for consumption. Ethyl carbamate was detected in sugarcane juice and during fermentation. During distillation, ethyl carbamate levels ranged from the limit of detection to 17.1 μg L−1. Ethyl carbamate increased during storage in wooden casks. The presence (or absence) of light did not affect the formation of ethyl carbamate in cachaca stored in glass containers. Copyright © 2017 The Institute of Brewing & Distilling

This study investigates the effect of double- or single-stage distillation and different alcohol content in ‘hearts’ (middle fractions) on the distribution of aroma volatiles and undesirable compounds (methanol, hydrocyanic acid, ethyl carbamate) during distillation of plum brandies. Irrespective of the distillation method used, the first fractions (‘heads’) included mainly aliphatic aldehydes, acetals and esters as well as higher alcohols (1-propanol, 2-methyl-1-propanol, 1-butanol, 2-methyl-1-butanol and 3-methyl-1-butanol). Furfural, 1-hexanol, benzyl alcohol, 2-phenylethanol and ethyl carbamate occurred in relatively high concentrations in the ‘tail’ fractions. Increasing the concentration of alcohol in the heart fractions from 70 to 90% v/v resulted in a gradual decrease in the concentration of all detected volatile compounds. Compared with single-stage distillation, double distillation produced heart fractions with lower concentration of acetaldehyde and benzaldehyde and with higher contents of furfural and esters, such as isobutyl acetate and isoamyl acetate. There was a statistically significant increase in the amounts of methanol and ethyl carbamate obtained from double distillation compared with similar fractions derived from the single-stage process. However, in all fractions these compounds occurred in concentrations much lower than the limits specified by EU regulations. The heart fraction from the double-stage process with 83% v/v alcohol content received the best scores for aroma and flavour. Copyright © 2017 The Institute of Brewing & Distilling

This study aimed to investigate the effects of different distillation patterns on main compounds of Chinese Luzhou-flavour liquor. Results showed that more volatiles of raw liquor might originate from fresh grains for a newly constructed pit. A modest (p = 0.05) increase in the total amount of volatiles was found in the heart liquor from fermented grains added to fresh grains and rice hulls to distillate (AG pattern), reaching a maximum value of 1012.22 mg/L. The percentage of esters in the AG pattern ranged from 81.22 to >95.03% compared with samples from fermented grains only added to rice hulls to distillate (NG pattern). Acids in the heart liquor obtained by the AG pattern were higher than those for NG, but the corresponding proportion was opposite. Alcohols were detected at ~1.62% in NG pattern but were 1.42% in AG. Cyanide and ethyl carbamate content in the head liquor were far higher than those in the heart and tail liquor. In particular, cyanide content dramatically increased after adding fresh grains during the distillation process. Copyright © 2017 The Institute of Brewing & Distilling

Cachaca is a beverage produced by the distillation of fermented must from sugarcane. During the manufacturing steps, producers commonly use naturally occurring yeasts in the preparation of the fermentation broth, resulting in spontaneous fermentation. The composition of the resulting beverages can vary greatly, especially if various species and strains of yeast are present. The beverages produced with selected yeast strains are an alternative, leading to the production of more standardized beverages. Ethyl carbamate, which is highly toxic and has carcinogenic potential, is among the possible contaminants. The objectives of this study were to determine the levels of ethyl carbamate in cachaca produced by different types of fermentation and follow its formation during the production stages. The cachacas that contained rice bran as a nutrient during the fermentation stage contained the highest levels of ethyl carbamate throughout the production process and storage. Copyright © 2016 The Institute of Brewing & Distilling

Ethyl carbamate (EC), which has been confirmed as probably carcinogenic to humans, can be formed during the alcoholic fermentation of Chinese rice wine. In this study, EC and two possible precursors (urea and arginine) were analysed in wines fermented from rice processed by enzymatic extrusion liquefaction pretreatment, with different wheat Qu content gradients from 6 to 18% (dry basis, d.b.). The EC concentration decreased 22.5% with the addition of wheat Qu reduced to 6% for the enzymatic extrusion-processed rice wine (EE). Moreover, although the arginine was generated 6.33–8.39 times higher in the enzymatic extruded rice, instead of the traditional treated rice at the same wheat Qu level, the corresponding level of urea formed from arginine was not high in the EE. In addition, rice treated by extrusion combined with enzymatic hydrolysis was found to be more utilizable and fermentable, and the lost quality of the final traditional rice wine with the low wheat Qu level (6–14%) could be improved using enzymatically extruded rice as the fermenting material. Therefore, it may be feasible to inhibit EC accumulation in Chinese rice wine by wheat Qu control, combined with enzymatic extrusion pretreatment for rice.

The aim of this study was to assess the influence of heat treatment of sugar cane juice, supplementation with urea and double distillation on the concentration of volatile congeners (acetic aldehyde, ethyl acetate, n-propyl, isobutyl and isoamyl alcohols and acetic acid) and contaminants (methanol, 1-propyl and 2-butyl alcohols, copper, and ethyl carbamate) in cachaca. Samples of fresh sugar cane juice, sugar cane juice submitted to heat treatment and contaminated sugar cane juice were supplemented (or not) with urea and fermented. The washes so obtained underwent single and double distillation. Supplementation with urea stimulated ethyl carbamate formation. The distilled products that originated from contaminated worts presented higher concentration of acetic acid and ethyl carbamate. Double distillation reduced the concentration of contaminants. The best quality pot still cachaca was obtained employing heat treatment of sugar cane juice, nonsupplementation with urea and double distillation. Copyright © 2015 The Institute of Brewing & Distilling

This study sought to evaluate the influence of natural light on the concentration of ethyl carbamate (EC) in cachacas aged in wooden barrels and stored in glass bottles for a period of 6 months. The quantification of EC was achieved by HPLC using a fluorescence detector after previous derivation of the samples and standards with 9-xanthydrol. All of the samples presented an EC concentration below the limit established by Brazilian legislation. The highest concentration found was 79.70 µg L−1. As for the influence of light and storage period, 70% of the samples exhibited an influence of these parameters. Copyright © 2015 The Institute of Brewing & Distilling

Most of the fermented alcoholic beverages, particularly Chinese rice wine, contain the potentially human carcinogenic compound ethyl carbamate (EC). As a major EC precursor in Chinese rice wine, urea in fermentations can be transported into the yeast cell by urea permease and finally metabolized by urea carboxylase and allophanate hydrolase in vivo. To eliminate EC in Chinese rice wines, the present study constructed high urea uptake yeast strains N1-D, N2-D and N-D, by introducing a strong promoter (PGK1p) into the urea permease gene (DUR3) of the industrial Chinese rice wine yeast N85, and by the restoration of the URA3 gene at the same time. With these self-cloned, high urea uptake strains, the urea and EC in the terminal Chinese rice wine samples were reduced to different extents. With two copies of overexpressed DUR3, the N-D strain could reduce the urea and the EC by 53.4 and 26.1%, respectively. No difference in fermentation characteristics was found between the engineered strains and the parental industrial yeast strain N85. These results could help to optimize the genetic manipulation strategy for EC elimination in Chinese rice wine production. Copyright © 2015 The Institute of Brewing & Distilling

This study aimed to assess the influence of the pot still configuration on the reduction of ethyl carbamate content in double-distilled sugar cane spirit, as well as to describe the effects of double distillation on this reduction. Ethyl carbamate is a potentially carcinogenic compound that may be present in high concentrations in sugar cane spirit, and therefore could become a public health problem, as well as a factor hindering Brazilian exports of this beverage. In sugar cane spirit production in Brazil, neither pot still configuration nor distillate reflux and cooling/condensation systems are standardized. In this study, ethanol, copper and ethyl carbamate contents were assessed (GC-MS) in sugar cane spirits that were double-distilled in pot stills with different reflux and cooling systems. Double distillation removed 94–98.5% of ethyl carbamate from sugar cane spirit. Pot stills with high reflux rates (equipped with dephlegmator or rectifying system) were more effective in reducing the ethyl carbamate content in double-distilled sugar cane spirit. Copyright © 2013 The Institute of Brewing & Distilling

Ethyl carbamate is an impurity present in distilled beverages. Given the risk of it being a carcinogenic substance, Brazilian legislation has determined that its presence in distilled beverages, such as ‘aguardente’ and ‘cachaca’ (two types of sugarcane spirits), should be limited to a maximum of 150 µg/L. Ordinary spirits usually contain variable amounts of ethyl carbamate, although in lower concentrations than the maximum determined by law. The finding that commercial spirits had a much lower concentration of this impurity (around 50 µg/L) led the authors to research the reasons for the differences, and these are explored in this paper, with a focus on the speed of the distillation process and its influence on the spirit's composition. The team conducted research in a sugarcane distillery producing ‘aguardente’ using a simple pot still and measured the influence of fast and slow distillation on the presence of ethyl carbamate and non-alcohol components in the process. The results demonstrated that the speed of distillation was proportionally related to the concentration of ethyl carbamate and secondary components in the beverage's composition. Copyright © 2012 The Institute of Brewing & Distilling

Ethyl carbamate (EC) is a naturally occurring toxic contaminant that may imply a risk to human health and is usually found in alcoholic beverages such as Chinese rice wine. An automated procedure for the rapid determination of EC in Chinese rice wine was developed by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC-MS). Using propyl carbamate as internal standard, the optimized HS-SPME sampling with a polyacrylic fibre was 45 min at 70°C after applying 38.8% NaCl to saturate the sample. This method showed good linearity over a range of 25–600 µg L−1 (R2 = 0.997). The recovery, relative standard deviation and limit of detection were 90.21–97.35%, lower than 2.89% and 1.19 µg L−1, respectively. Additionally, the ethanol concentration had no effect on the analysis of EC. The total analysis time of 57 min per sample in continuous determination was twice as fast as the widely used solid-phase extraction–GC-MS method. This solvent-free HS-SPME-GC-MS procedure is suitable for the rapid, automated, and therefore convenient, determination of EC in Chinese rice wine. Copyright © 2012 The Institute of Brewing & Distilling

The aim of this study was to verify the effect of a double distillation on the reduction of the ethyl carbamate content in sugar cane spirit. Ethyl carbamate is a potentially carcinogenic compound normally present at critical levels in sugar cane spirit, constituting a public health problem and therefore hindering the export of this beverage. The ethanol, copper and ethyl carbamate contents were evaluated, using gas chromatography/mass spectroscopy, during a double distillation of the fermented sugar cane juice. The distillate fraction from the first distillation accumulated 30% of the ethyl carbamate formed. In the second distillation, the ethyl carbamate and the copper content increased during the process as the alcohol content decreased, and only 3% of the ethyl carbamate formed was collected in the spirit. Double distillation decreased the ethyl carbamate content in the sugar cane spirit by 97%. Copyright © 2012 The Institute of Brewing & Distilling

An analytical method for the determination of ethyl carbamate in alcoholic beverages has been developed and optimized. A combination of headspace solid phase microextraction (HS-SPME), as the extraction technique, and GC/MS, as the determination technique, was utilized. Analytical grade ethyl carbamate dissolved in ethanol solution was analyzed to determine the optimum analytical conditions. Ethyl carbamate-d5 was added as an internal standard. The following HS-SPME conditions were investigated: type of stationary phase of the fibre, ethanol content, sample volume and extraction time. The optimized procedure showed that the detection limit, relative standard deviation, and recovery were 6.7 μg/L, 0.4–2.0%, and 103.6–107.6%, respectively. The precision of this new method was equivalent to previous analyses. Finally, the developed method was applied to the analysis of ethyl carbamate in sake.

There are residual organic and inorganic contaminants in the cachaca production chain. Among the organic contaminants, ethyl carbamate has been widely studied. It is formed naturally during the fermentation processes and can be found in many foods and beverages such as bread, yoghurt, wine, beer and especially in fermented–distilled beverages such as whiskey, rum, vodka, grappa, cachaca and tiquira. The objective of this study was to identify and quantify ethyl carbamate during the steps of the production process and aging of cachaca in oak (Quercus sp) and amburana (Amburana cearensis) barrels. The cane used for cachaca production, as well as the process for obtaining the fermentation broth, did not affect the formation of ethyl carbamate, as it was not detected. Carbamate was detected in low concentrations, but was not quantified, in the fermentation, distillation and aging steps. Copyright © 2014 The Institute of Brewing & Distilling

The aging process of distilled spirits is a complex system based on the extraction of molecules from the wood and interactions with the liquid, the phenomenon of migration of wood constituents, as well as the formation and degradation of several compounds. Volatile and maturation-related congeners were evaluated during the aging process of cachaca, a Brazilian sugarcane spirit aged in oak barrels. Aged cachaca presented alterations in the levels of ethanol, higher alcohols, acetaldehyde, volatile acidity, ethyl acetate, total volatile congeners, isoamyl alcohol, ethyl carbamate and copper. The aging markers (gallic acid, furfural, 5-hydroxymethylfurfural, vanillic acid, syringic acid, vanillin, syringaldehyde, sinapaldehyde and coniferaldehyde) were compared with the compounds found in whisky, cognac, armagnac, bourbon and brandy. Monitoring the generation and evolution of congeners during the aging process allowed the characterization of cachaca and the identification of product maturity. Copyright © 2014 The Institute of Brewing & Distilling

Ethyl carbamate, also known as urethane, is the ethyl ester of carbamic acid. Animal studies with this compound have demonstrated its carcinogenic potential. In this study, gas chromatography coupled to mass spectrometry (GC-MS) was applied for the determination of ethyl carbamate in sugar cane spirits in the northern and southern regions of the state of Minas Gerais in Brazil. The samples were collected from distillates from small- and medium-scale stills. The concentrations determined for ethyl carbamate in the samples ranged from 23 to 980 µg L−1. All of the samples analysed from the southern region of Minas Gerais had an ethyl carbamate content below the limit set by the Brazilian legislation for ethyl carbamate of 150 µg L−1, while a number of samples from northern Minas Gerais exceeded this limit. No correlations were observed between the levels of ethyl carbamate and the alcohol content, acidity or copper concentrations in the samples. Copyright © 2014 The Institute of Brewing & Distilling

Sugarcane spirit is the most consumed distilled beverage in Brazil. Currently the manufacturing industries are trying to widen their market and attract new consumers, and thus it has become necessary to elevate the product to national and international quality standards. This study's aim was to determine the influence of subsequent distillations on the composition of organic sugarcane spirit. From mono-distilled organic sugarcane spirit, bi-, tri-, tetra- and penta-distilled sugarcane spirits were obtained, and analysed for the following: relative density, alcoholic degree, volatile acidity, pH, copper, methanol, aldehydes, furfural, esters, ethyl carbamate and higher alcohols. The most relevant results were reductions of 69.57% volatile acidity, 98.4% copper, 40.9% methanol, 71.5% aldehydes, 100% esters, 100% ethyl carbamate and 32.2% higher alcohols in the penta-distilled sugarcane spirit, as compared with the mono-distilled. It was concluded that subsequent distillations would put sugarcane spirit in line with the international standards for distilled beverages. Copyright © 2013 The Institute of Brewing & Distilling

Ion chromatographic procedures are described for the identification and determination of a series of cyanide related precursors involved in ethyl carbamate formation in maturing grain whisky produced by the continuous distillation Coffey still process. These precursors include cyanide and copper cyanide complex anions, lactonitrile and isobutyraldehyde cyanohydrin (collectively determined as “measurable cyanide” or MC) and cyanate and thiocyanate anions. The components comprising MC may be determined individually using a pre-chromatographic separation procedure based on anion exchange resins. These techniques have been shown to be applicable for monitoring precursors involved in post-distillation ethyl carbamate formation in maturing grain whisky. Similar ion chromatographic procedures are described for the detection of a range of copper salts, incorporating cyanide, cyanate and thiocyanate, which are naturally occurring deposits within the copper Coffey still. These results are correlated with those based upon X-ray diffraction and secondary ion mass spectrometric techniques. Species identified included cuprous cyanide, cuprous thiocyanate, cuprous oxide, cuprous and cupric sulphide and copper cyanide cluster ions such as CuCN−, Cu(CN)2−, Cu2(CN)3− and Cu3(CN)4− and mixed species Cu(CN)2S−, CuSCN− and CuCNO+. In addition, an ion chromatographic procedure developed to investigate the role of carbamyl phosphate in ethyl carbamate formation, showed that conversion took place by means of its thermal decomposition into cyanate ion.

Distilled spirits are subject to post-distillation ethyl carbamate formation in the presence of appropriate precursors. Freshly distilled grain whisky, produced by the continuous distillation Coffey still process, normally contains ethyl carbamate concentrations not exceeding 20 ppb (normalized to 43% v/v alcoholic strength). Further ethyl carbamate formation, dependent upon the presence of trace anionic precursors such as cyanate, cyanide, and copper cyanide complexes, may take place during normal maturation in oak casks. Related but different mechanisms may induce ethyl carbamate formation under normal daylight and artificial light in the laboratory. Ethyl carbamate precursors convert into ethyl carbamate during the initial three months of maturation and are not detectable in the final bottled product. Thus the final ethyl carbamate concentration in spirit is dependent upon the initial ethyl carbamate level measured after distillation plus ethyl carbamate formed from precursors. It is important during process control to monitor not only the ethyl carbamate level in freshly distilled spirit but also the spirit's potential to form ethyl carbamate from precursors with the objective of minimizing these components in the freshly distilled and maturing spirit. A scheme for predicting final ethyl carbamate concentrations from precursor concentrations in freshly distilled spirit is presented.

Low concentrations of ethyl carbamate, which may occur in distilled spirits are shown to originate from traces of cyanide, produced in distillates by thermal decomposition of the cyanohydrin of isobutyraldehyde (IBAC) which is present in fermented wash. This compound arises during fermentation by the hydrolytic action of yeast beta-glucosidase on a naturally-occurring cyanogenic glycoside, identified as epiheterodendrin (EPH). EPH, which is a heat-stable precursor of IBAC is located in the acrospires of malted barley and is readily transferred to worts during mashing. Although many barley varieties display the ability to produce volatile cyanide, some low-yielders have been identified. EPH is absent from unmalted barley and its development is strongly influenced by malting conditions. Conversion of measurable cyanide (MC) into ethyl carbamate takes place during- or after distillation but, apparently, not before.

A new rapid method for the determination of malt glycosidic nitrile, using an enzymatic incubation with beta-glucosidase, was tested in an inter-laboratory collaborative trial. Repeatability (r 95 ) and reproducibility (R 95 ) values are reported. A limited comparison is made with the existing determination of malt combined nitrile using methods involving laboratory fermentations.

The formation of radioactive ethyl carbamate from added H14CN was studied in a sample of new spirit from a grain distillery. Reaction conditions were at ambient temperature in the dark. Cupric ions added to spirit promoted the incorporation of cyanide into ethyl carbamate.

Gas chromatographic methods are described for the determination of naturally occurring ethyl carbamate in distilled spirits at levels as low as 5 ppb. Bottled products, such as whisky, gin and brandy, are extracted in the presence of n-propyl carbamate as internal standard and analysed by capillary column gas chromatography with either nitrogen specific or mass spectrometric detection. A shorter extraction procedure is satisfactory when the more sensitive and selective mass spectrometric detection is used. Direct sample injection without extraction may be used for higher alcoholic strength cask and new-make samples. Analysis of 181 blended Scotch whisky samples indicated ethyl carbamate concentrations ranging from 20 to 75 ppb. Concentrations in 48 malt whiskies ranged from 15–100 ppb. Ethyl carbamate was not detected in gin, vodka and rectified neutral alcohol. All concentrations in bottled product fell below the Canadian limit of 150 ppb in distilled spirits.

Ethanolic solutions of bovine serum albumin or wheat gluten were shown to form ethyl carbamate subsequent to distillation or reflux in the presence of copper. Substitution of propanol for ethanol resulted in the formation of propyl carbamate. The reflux of an ethanolic solution of essential amino acids, in the presence of copper, did not result in significant formation of ethyl carbamate.