Ethyl Carbamate in Foods and Beverages – A Review

Abstract

Foods and beverages contain many toxic chemicals that raise health concerns. Ethyl carbamate (EC) or urethane is the ethyl ester of carbamic acid. It occurs at low levels, from ng/L to mg/L, in many fermented foods and beverages. EC is genotoxic and carcinogenic for a number of species such as mice, rats, hamsters and monkeys. It has been classified as a group 2A carcinogen, "probably carcinogenic to humans", by the World Health Organization's International Agency for Research on Cancer (IARC) in 2007. The benchmark dose lower limit of EC is 0.3 mg/kg bw/day and the mean intake of EC from food is approximately 15 ng/kg bw/day. Those levels were calculated for relevant foods including bread, fermented milk products and soy sauce. Alcoholic beverages were not included in this calculation. However, high levels of EC can be found in distilled spirits at concentrations ranging from 0.01 mg/L to 12 mg/L depending on to the origin of spirit. Alcoholic drinks should thus be considered as a source of EC. EC is produced by several chemical mechanisms: first, from urea and various proteins like citrulline produced during the fermentation step, and second from cyanide and hydrocyanic acid, via EC precursors such as cyanate. A large panel of EC formation mechanisms is described from simple ethanolysis of urea in homogeneous liquid phase to photochemical oxidation of cyanide ion or complex heterogeneous gas/solid catalytic reactions. Determination of EC in foods and beverages involves various strategies according to the material, food or beverage, solid or liquid, and according to the concentration, from ng/L to mg/L. Usually adapted extractive techniques and pre-concentration steps are followed by analysis by gas chromatography coupled to mass spectrometry (GC-MS of GC-MS-MS). High-performance liquid chromatography (HPLC) and semi-quantitative spectroscopic methods (infra-red) are also proposed as valuable alternatives to the classical but time-consuming GC-MS. Various preventing methods are developed and used in some cases at industrial scale to lower EC levels in food. Two types of preventing methods are described. practices in all steps of the chain of food (or beverages) production lead, in general, to low EC level. Secondly, the abatement of EC precursors can be done by adapted enzymatic, physical-chemical or chemical methods according to the nature of raw materials and conditions of their production processes.

Effect of ‘wheat Qu’ addition on the formation of ethyl carbamate in Chinese rice wine with enzymatic extrusion liquefaction pretreatment

“…Similar results on free arginine (8.2–77.6 and 73.4–586.2 mg/kg in rice and wheat Qu, respectively) and urea (3.3–6.6 and 19.1–29.7 mg/kg in rice and wheat Qu, respectively) were previously reported . It has been demonstrated that a greater amount of arginine during fermentation could be catabolized to generate more urea after being taken into the yeast cell, and this could result in even more EC formed in the final wine product . In addition, the wheat Qu contained more protein than the rice, which indicates a potential resource for EC formation, as total amino acids are also possible indirect precursors of EC .…”

The arginine deiminase pathway of koji bacteria is involved in ethyl carbamate precursor production in soy sauce

“…Ethyl carbamate (EC) is a byproduct generated during fermentation process that belongs to the 2A group of carcinogen (Beland et al, 2005;Coulon et al, 2006). It is widely persisted in brandy, bread, yogurt, Chinese rice wine, and traditional condiment soy sauce (Battaglia et al, 1990;Matsudo et al, 1993;European Food Safety Authority, 2007;Koh & Kwon, 2007;Weber & Sharypov, 2009). EC is formed from various precursors (Ough et al, 1988) through a reaction promoted by heat and acid condition with ethanol (Kitamoto et al, 1991).…”

Functional enhancement of Sake yeast strains to minimize the production of ethyl carbamate in Sake wine

“…2005). As it is found in most alcoholic beverages in the μg l −1 range (Weber and Sharypov 2009), exposure to EC may be increased by the regular consumption of alcoholic beverages, and this may be a factor involved in human cellular mutagenesis and resultant tumorigenesis (Zimmerli and Schlatter 1991; Park et al. 2009).…”

“…Furthermore, EC has been shown to cause various cancers in a variety of test animals (Leithauser et al 1990;Schlatter and Lutz 1990;Hubner et al 1997;Beland et al 2005). As it is found in most alcoholic beverages in the lg l )1 range (Weber and Sharypov 2009), exposure to EC may be increased by the regular consumption of alcoholic beverages, and this may be a factor involved in human cellular mutagenesis and resultant tumorigenesis (Zimmerli and Schlatter 1991;Park et al 2009). As a result, winemakers have been actively reducing EC levels in wines by both agricultural practices, wine-making practices and, more recently, molecular biological means (Kitamoto et al 1991;Butzke and Bisson 1998;Yoshiuchi et al 2000;Park et al 2001;Schehl et al 2007).…”