What role does the egg yolk powder (lead oxide) in Songhua preserved eggs play in preserved eggs?

When processing preserved eggs, you need to mix soda ash, lime, salt and yellow red powder in a certain proportion, then add mud and bran to wrap the outside of the duck eggs. After two weeks, delicious preserved eggs will be ready. Made.

“Yellow red powder is lead oxide, which can produce beautiful patterns on eggs.”

But if yellow red powder is used, the preserved eggs will be contaminated by lead. According to national regulations, the lead content of every 1,000 grams of preserved eggs shall not exceed 3 mg. Preserved eggs that meet this standard are also called lead-free preserved eggs. Therefore, "lead-free preserved eggs" does not mean that they do not contain lead, but that the lead content is lower than the national standard.