Test for chemical formation of ethylcarbamate (CAE) in the alcoholic beverages was carried out.
The samples of the model alcoholic beverages (: 0.1M acetate buffer solutions at various pH containing 5-20% of ethyl alcohol) containing urea or its related compounds at various concentrations (10-200 ppm) were either allowed to stand for 10-90 days at 25-55°C or heated under reflux for a few hours.These samples were extracted three times with chloroform and the extracts were concentrated about 100 times. The amounts of CAE in the samples were determined by GLC.The results obtained as follows.
(1) CAE was formed by reactions of urea, potassium cyanate, carbamyl phosphate, L-citrulline, carbamyl-DL-aspartic acid and ethylurea respectively with ethyl alcohol under the above mentioned conditions for heating.Especially, the amount of CAE formed from urea or potassium cyanate was larger than that of the other compounds.
(2) The amounts of CAE formed from urea in the model alcoholic beverages were influenced by the.ethanol concentration and pH, and it was larger at higher concentration of ethyl alcohol and at neutral pH than acidic pH.
(3) The amounts of CAE formed from urea in the model alcoholic beverages were markedly influenced by the reaction temperature and the concentration of urea added.The rate of CAE formation
(
v) was given by the following equation in the case of 20% ethanol solution at pH 4.3.
v-
s0×10
24exp (-A/RT)-
s0×3.44×10
24exp (-18, 200/
T)
T: Absolute temperature, (°K)
s0: Concentration of urea added (ppm)
v: Rate of CAE formation: Concentration of CAE formed (ppb)/day
R: Gas constant 1.986 (cal/mol, °K)
A: Fnergv of activation 36, 100 (cal/mol)
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