The Protein Digestibility Corrected Amino Acid Scoring (PDCAAS) is a method for analyzing proteins and the quality of proteins in comparison to their effect on humans and how easy they are to digest. The PDCAAS is on a scale of 0.0 to 1.0 and can then be used to help calculate the daily value to go on food labeling. For example, here are the PDCAAS values of some common foods: egg white (1.0), beef (.92) and canned kidney beans (.68).
Look at the protein you are testing and determine its amino acid profile: what amino acids make up the protein and how much of each amino acid there is in proportion to the protein as a whole (usually in milligrams of amino acid per gram of protein).
Find out which amino acid is the most limiting — which has the lowest amino acid score. Each amino acid’s score is determined by dividing its proportion (from Step 1) by the amount needed by a preschool-age kid (considered the reference point or control point for digestibility).
Find the protein’s digestibility score. This is determined by studies in rats and can be found in tables produced by scientists.
Calculate the PDCAAS. Take the protein digestibility amount from Step 3 and multiple it by the limiting amino acid score from Step 2.