Parboiling

Parboiling - the partial boiling of food in order to finish cooking it later.

This helps to remove the scum from the meat for soups. 

Your soup will remain clear and free from scum...

A layer of scum on top of the water...

To parboil the meat for cooking soup:

Boil a pot of water. Put the meat in and cook for 5-10 minutes. 

Remove it from the pot and do a quick rinse with water from tap.

Parboiled meat is now ready for use to cook your soup.