Comparison of methodologies used to define the protein quality of human foods and support regulatory claims.

Protein quality (PQ) is the capacity of a protein to meet the amino acid (AA) requirements of an individual. There are several methodologies for determining the PQ of foods. The protein efficiency ratio is an animal growth bioassay. The protein-digestibility-corrected AA score considers the AA requirements of a reference population, and the true nitrogen digestibility coefficient for each ingredient. The digestible indispensable AA score is based on true ileal AA digestibility and better represents bioavailability of AAs. In vitro techniques for assessment of PQ are available but require validation against a greater range of protein sources. Isotopic methods, such as the indicator AA oxidation and dual tracer techniques measure AA relative bioavailability and digestibility, respectively, but require sophisticated equipment, and may not be cost nor time effective for the industry to adopt. The present review discusses advantages and disadvantages of methodologies for determining PQ of food for humans focused on methods that are or could be adopted by regulatory agencies. Understanding the framework and resources available for PQ determination will help in the selection of appropriate methods depending on the application. Understanding the framework and resources available for PQ determination will help in the selection of appropriate methods depending on the application.