Natural foods usually contain trace amounts of aluminum. If you want to know whether the aluminum content in a vermicelli comes from your own raw materials or artificially added alum, you must consider the "aluminum background value" of the raw materials.
Generally speaking, the aluminum content of common food is below 5mg/kg, and the aluminum content of tuber plants such as sweet potato and potato is high, but it is generally considered that the aluminum content of 10mg/kg is low, and it is not recommended to exceed 20mg/kg at the highest.
Extended data:
China's vermicelli standard stipulates that the aluminum content should meet the requirements of the National Limits of Pollutants in Food, but the current Limits of Pollutants in Food has cancelled the aluminum content. However, in China's Hygienic Standard for the Use of Food Additives, only foods with potassium aluminum sulfate (alum) are allowed, such as fried dough sticks and puffed foods, and the aluminum residue is ≤ 100mg/kg. As for starch products such as vermicelli, it is only mentioned that alum cannot be used.
In fact, in Beijing, Guangzhou, Xining, Changsha and other places, although the regulatory authorities have tested the aluminum content of fans, they have all implemented the "no aluminum detection" rule, but the final evaluation values are still different. In some places, the content of aluminum in fried dough sticks is ≤ 100mg/kg, and if it exceeds this limit, it is judged that alum is artificially added. But in some places, the restrictions are more stringent. For example, 44. 1mg/kg aluminum is detected in Guangzhou, which is regarded as excessive addition of alum aluminum.
References:
Baidu encyclopedia-fans
References:
People's Network -4 kinds of sample vermicelli, 3 kinds of aluminum content is too high to cook for a long time, beware of alum vermicelli.