2. The lotus root is not washed clean.

3. I don't think lotus root will change color when exposed to oxygen.

If it is the third, there are the following solutions:

1, put a few drops of vinegar in clear water to soak the cut lotus root.

2. add water to the pot and put a few drops of vinegar to scald the lotus root.

It's too cold to use vinegar water.

4. Boil the ribs again.

5, put a little oil in the pot, add aniseed onion and ginger to stir fry, add a little cooking wine to drain water and ribs, add salt and lotus root after 2 hours of low heat, 1 hour and then put monosodium glutamate sesame oil out of the pot.