List and explain the factors that influences protein quality?

The quality of a protein depends on the number of and in some instances the amount of amino acids it contains in order to make it a complete protein. There are 21 amino acids needed by humans for a protein to be regarded as complete and 8 of them are called essential because the human body cannot synthesize them from other compounds. It would be too time consuming and lengthy to list all of them here, their functions and how to supplement incomplete proteins with other proteins to make them complete but in most instances meat is always a complete protein. Milk is almost complete but has too little of one of the amino acids but bread has an abundance of that particular amino acid so when you combine milk with bread you have a complete protein. Other complementary examples are macaroni and cheese, beans and corn, beans and rice.