Ethyl carbamate (EC) commonly found in fermented beverages has been verified to be a multisite carcinogen in experimental animals. EC was upgraded to Group 2A by the Intl. Agency for Research on Cancer (IARC) in 2007, which indicates that EC is a probable carcinogen to humans. Because of its threat to human safety, the presence of EC may be a big challenge in the alcoholic beverage industry. During the past few years, thorough and systematic research has been carried out in terms of the generation of EC in order to meet the allowed limitation levels in fermented beverages. Previous studies have indicated that EC primarily results from the reaction of ethanol and compounds containing carbamyl groups. These main EC precursors are commonly generated from arginine metabolism by Saccharomyces cerevisiae or lactic acid bacteria accompanied by the fermentation process. This review comprehensively summarizes the genotoxicity, analytical methods, formation pathways, and removal strategies of EC in various beverages. The article also presents the metabolic mechanism of EC precursors and pertinent metabolites, such as urea, citrulline, and arginine.

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Abstract:With the rising awareness of a healthy lifestyle, natural functional foods have gained much interest as promising alternatives to synthetic functional drugs. Recently, wild Agaricus bisporus (Lange) Sing. Chaidam has been found and artificially cultivated for its thick fresh body and excellent taste, with its antioxidant and anti-hypoxic abilities unknown. In this work, the antioxidant potential of its methanolic, 55% ethanolic, aqueous extracts and crude polysaccharide was evaluated in different systems. The results showed that polysaccharide was the most effective in scavenging ability on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals, metal chelating activity and reducing power, with EC50 values of 0.02, 2.79, 1.29, and 1.82 mg/mL, respectively. Therefore, we further studied the anti-hypoxic activity of crude polysaccharide. The results turned out that polysaccharide (300 mg/kg) prolonged the survival time, decreased the blood urea nitrogen and lactic acid content as well as increased the liver glycogen significantly, compared with the blank control and the commercialized product Hongjingtian (p < 0.05). With such excellent activities, we purified OPEN ACCESSMolecules 2015, 20 17776 the polysaccharide and analyzed its molecular weight (120 kDa) as well as monosaccharide components (glucose, fructose and mannose). This study indicated that wild Agaricus bisporus (Lange) Sing. Chaidam had strong potential to be exploited as an effective natural functional food to relieve oxidative and hypoxia stresses.

Ethyl carbamate (EC) is a potential carcinogen that forms spontaneously during Chinese rice wine fermentation. The primary precursor for EC formation is urea, which originates from both external sources and arginine degradation. Urea degradation is suppressed by nitrogen catabolite repression (NCR) in Saccharomyces cerevisiae. The regulation of NCR is mediated by two positive regulators (Gln3p, Gat1p/Nil1p) and two negative regulators (Dal80p/Uga43p, Deh1p/Nil2p/GZF3p). DAL80 revealed higher transcriptional level when yeast cells were cultivated under nitrogen-limited conditions. In this study, when DAL80-deleted yeast cells were compared to wild-type BY4741 cells, less urea was accumulated, and genes involved in urea utilization were up-regulated. Furthermore, Chinese rice wine fermentation was conducted using dal80Δ cells; the concentrations of urea and EC were both reduced when compared to the BY4741 and traditional fermentation starter. The findings of this work indicated Dal80p is involved in EC formation possibly through regulating urea metabolism and may be used as the potential target for EC reduction.