In conjunction with increased consumer interest in dietary protein, there has been increased demand for alternative sources of protein that go beyond animal-based protein. Inherent in this shift is the requirement not only for alternative sources of protein, but for sources of high-quality protein that are comparable to the nutrient quality found in protein derived from animals. Currently, the primary alternative to animalbased protein sources is plant-based sources such as soy, cereals, and pulses. Although plant proteins are frequently found in whole foods, processing of plants to extract a high-protein fraction for use as an ingredient in other foods is becoming more common. The quality of a protein source encompasses both the amino acid composition of the protein and the ability of that protein to be digested, absorbed, and used for metabolic functions. The regulations for quantification of protein quality differ between nations, but in North America there are two indices: the protein efficiency ratio (PER) (11) in Canada and the protein digestibility-corrected amino acid score (PDCAAS) (9) in the United States. Although a new method of determining protein quality has recently been introduced, the digestible indispensable amino acid score (DIAAS) (8), it is not currently recognized in any regulatory capacity.The PER is a growth assay (11). Weanling rats are fed a diet containing 10% protein for a period of 28 days, during which diet consumption and weight gain are measured regularly. After