Mecanismos de formação do carbamato de etila durante a produção e estocagem de aguardente de cana-de-açúcar

• Autor(a) principal: Baffa Júnior, José Carlos
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/460
• topic: Carbamato de etila; Cachaça; Fermentação; GC/MS; Ethyl carbamate; Cachaça; Fermentation; GC/MS; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS

The ethyl carbamate (EC) or urethane is an ethyl ester of carbamic acid that occurs at low levels (ng / L or mg / L) in many fermented foods such as wines and spirits, whiskey and rum. The EC is genotoxic and carcinogenic to a large number of species including rats, mice and monkeys. The compound has been classified by the World Health Organiz ation (Agency for Research on Cancer) as belonging to group 2A, which means that it is carcinogenic to humans. Its limit of acceptable daily intake (ADI) is 0.3 ng.Kg-1 per day, but that level was calculated by studies in foods such as bread and fermented milk products. The spirits were not included in these calculations despite being the largest products were contaminated by ethyl carbamate, reaching values of 12 mg / L. So drinks like rum should be considered a major source of this toxic compound, even in countries like Brazil, where consumption of the product is high. The Ministry of Agriculture and Livestock and Food Supply of Brazil by Instruction No. 13, June 21, 2005, proposes 150 mg / L as the upper limit of the contaminant in cachaça. However there is no knowledge of (s) your (s) route (s) of training in the production of rum. Three hypotheses are presented, but need to be confirmed by further studies. First there is the possibility of urea, derived from the metabolism of the main process of yeast, Saccharomyces cerevisiae, reacts with ethanol to form ethyl carbamate during the fermentation process. To analyze this hypothesis we analyzed the process of fermentation aliquots were removed for analysis of the amount of the compound. The content of ethyl carbamate after fermentation was 122,076 microg.L -1. The hypothesis was confirmed by increasing the concentration of urea in the broth and hence promote further formation of carbamate. We analyzed the distillation step in fractions head, heart and tail that had content microg.L 59700-1, 52 μg.L-1-1 microg.L and 1570 CE respectively. To the residue contained in the copper still, the stillage concentration of ethyl carbamate was 53,070 μg.L-1. Another hypothesis was verified a chain of reactions involving compounds glicocianogênicos using copper as catalyst for the formation of ethyl carbamate. In this study we can conclude that there is more than one mechanism of formation of ethyl carbamate during fermentation. The second mechanism is related to cyanogenic compounds that undergo oxidation releasing the cyanide reacts with ethanol to form EC. Finally, a third mechanism is correlated with the concentration of arginine, even at low concentration in the urea cycle would provide a greater formation of urea and a larger formation of ethyl carbamate. Fermentation is the step that produces the most ethyl carbamate, in mg levels may be associated with the combination of these three training courses. Finally the possibility of a photochemical reaction after distillation for ethyl carbamate formation involving ultraviolet light, and copper compound has been verified glicocianogênicos. Cachaças bottles packed in amber, tranaparente, green and blue, with and without copper were evaluated for 90 days. Returned results where after 90 days of storage show that copper is the catalyst of the reaction, because the treatments without copper had a lower mean concentration of ethyl carbamate to the end (62 μg.L-1). The treatment with 5.0 mg.L-1 and 10 mg.L-1 of copper averaged 164 and 228 μg.L-1content of CE, respectively. Also after 90 days of analysis we can say that the higher the alcohol content higher the concentration of carbamate formed. The levels of alcohol assessed 40 º GL, 45 GL and 50 had an average GL was 115.98 μg.L-1 of EC, 131.65 and 150.67 μg.L-1. In experiments that would evaluate the interference of light, specifically ultraviolet amber bottles exhibited an average content of carbamate 60% less than the bottle green, blue and transparent to the end of 90 days of storage. As for the cyanogenic compounds in the distillate absence of ultraviolet light (amber bottle) achieved a reduction of only 9%, 10% and 14% in cachaças without copper, copper in the limit (5.0 mg L-1) and copper 2 times the limit (10 mg.L-1) respectively. But in the presence of ultraviolet light to reduce cyanogenic compounds was 12%, 18% and 24% without copper, copper in the limit (5.0 mg L-1) and copper 2 times the limit (10 mg.L-1), respectively. We can then conclude that the oxidation process of cyanogenic compounds by ultraviolet light and its conversion into ethyl carbamate by reaction with ethanol exists. Therefore, as preventive measures in order to prevent the formation of carbamate, we recommend storage of liquor bottles in amber in the absence of copper after distillation with a collection of separate fractions (head, heart and tail).