What is the deal with urea being added to fishmeal?
About the issue of urea being added to fishmeal
This post was last edited by zangon on 2009-11-25 14:10
In the national standard for fishmeal GB/T19164-2003, why is the urea content required to be no more than 0.7%?
The specified detection method is based on the reaction of urea with p-dimethylaminobenzaldehyde (DMAB) under ethanol and acidic conditions to form a yellow substance, which has maximum absorption at a wavelength of 420nm, and the absorbance has a linear relationship with the urea concentration. By checking the standard curve, the urea content in the sample is calculated.
Why does the national standard not require that it be undetectable? Is it possible that there are other substances in fishmeal that could be mistakenly detected as urea by this method???
Very puzzled, please experts enlighten me!!!!
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According to Li Xiaochuan and Wang Lianzhu, drafters of the GB/T19164-2003 "Fishmeal" standard:
Urea exists in trace amounts in fish and shellfish tissues, and together with trimethylamine oxide it plays a role in regulating osmotic pressure. Therefore, trace amounts of urea can also be detected in normal fishmeal. In order to better supervise the behavior of adding urea to fishmeal, protect high-quality fishmeal, and crack down on inferior fishmeal, in this revision we set a limit value for urea in fishmeal. Based on our testing data from a large number of fishmeal samples, we concluded: the urea content of special-grade products is <=0.3%, and the urea content of first-grade, second-grade and third-grade products is <=0.7%.
In addition, according to the theory of protein metabolism in animal biochemistry, a urea cycle process exists in the fish body, namely:
Arginase
Arginine+H2O-----------Ornithine+Urea. It can be seen that the source of urea in the fish body is the metabolism of amino acids.
From the above content, it can be seen that because fish tissues contain trace amounts of urea, GB/T 19164-2003 "Fishmeal" sets a limit for urea.
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Work out your nutritional indicators so that everyone can comment conveniently.
--------------------------------------
Yes, teachers, please pass on your knowledge to us. Thank you very much
In the national standard for fishmeal GB/T19164-2003, why is the urea content required to be no more than 0.7%?
The specified detection method is based on the reaction of urea with p-dimethylaminobenzaldehyde (DMAB) under ethanol and acidic conditions to form a yellow substance, which has maximum absorption at a wavelength of 420nm, and the absorbance has a linear relationship with the urea concentration. By checking the standard curve, the urea content in the sample is calculated.
Why does the national standard not require that it be undetectable? Is it possible that there are other substances in fishmeal that could be mistakenly detected as urea by this method???
Very puzzled, please experts enlighten me!!!!
--------------------------------------
According to Li Xiaochuan and Wang Lianzhu, drafters of the GB/T19164-2003 "Fishmeal" standard:
Urea exists in trace amounts in fish and shellfish tissues, and together with trimethylamine oxide it plays a role in regulating osmotic pressure. Therefore, trace amounts of urea can also be detected in normal fishmeal. In order to better supervise the behavior of adding urea to fishmeal, protect high-quality fishmeal, and crack down on inferior fishmeal, in this revision we set a limit value for urea in fishmeal. Based on our testing data from a large number of fishmeal samples, we concluded: the urea content of special-grade products is <=0.3%, and the urea content of first-grade, second-grade and third-grade products is <=0.7%.
In addition, according to the theory of protein metabolism in animal biochemistry, a urea cycle process exists in the fish body, namely:
Arginase
Arginine+H2O-----------Ornithine+Urea. It can be seen that the source of urea in the fish body is the metabolism of amino acids.
From the above content, it can be seen that because fish tissues contain trace amounts of urea, GB/T 19164-2003 "Fishmeal" sets a limit for urea.
--------------------------------------
Work out your nutritional indicators so that everyone can comment conveniently.
--------------------------------------
Yes, teachers, please pass on your knowledge to us. Thank you very much