Essential amino acids are critical for building protein. For more information, see the Wikipedia page on them.
Protein Quality Score: 100%†
Limiting Amino Acid: Lysine
Some foods that are a good source of Lysine include eggs, meat (specifically red meat, lamb, pork, and poultry), soy, beans and peas, cheese (particularly Parmesan), and certain fish (such as cod and sardines).
100g of Beef Liver contains 29.1g of protein, which is about the same as
1.1 chicken breasts, or
2.1 cups (565g) of black beans.
† - Not adjusted for digestibility. See the tables
Profile of Carbohydrates in Item
Fraction of Carbs by Type
* Other includes oligosaccharides and other polysaccharides.