Caustic soda, sodium hydroxide, is a highly corrosive "high-risk chemical". However, caustic soda is also a "processing aid that can be used in various types of food processing and does not require a residual amount. " It is a highly efficient Acidity regulator. However, caustic soda used for food processing needs "food grade", and many reports mention "illegal merchants use industrial caustic soda". The difference between food grade caustic soda and industrial caustic soda is not the main component, but the former Heavy metal impurities require monitoring, the latter does not. In fact, the use of sodium hydroxide in food is the responsibility of the staff. In the final food, their "corrosiveness" has long ceased to exist. As for the use of industrial caustic soda , It belongs to the use of "unqualified raw materials" and should be cracked down. Among the following options, what does not match the meaning of this text:. ['Industrial caustic soda contains a large number of heavy metal impurities and cannot be used in food processing.', 'The use of caustic soda in food processing poses a risk of corrosion by workers.', 'The use of caustic soda in food processing is not illegal, and there is even no regulation on its residual amount.', 'The main components of food-grade caustic soda and industrial caustic soda are basically the same, and both can be used as acidity regulators.']