Our major source of protein is soy protein concentrate, which is a good source of fiber, as well as folate, copper, magnesium, manganese, molybdenum, potassium, phosphorus, and iron, but most importantly, it’s the only commonly consumed plant protein that’s comparable in quality to animal protein.
Protein quality is typically defined in terms of protein digestibility-corrected amino acid score (PDCAAS), which is a measure of its essential amino acid composition and digestibility. Higher PDCAAS means higher quality, with 1.00 being the highest score possible. Soy protein concentrate (the ingredient that contributes most of the protein in the Impossible Burger), has a published PDCAAS of 0.95. For reference, conventional ground beef from cows has a published PDCAAS of 0.92.
Soy protein’s high PDCAAS means you get plenty of nutritional bang for your buck with the Impossible Burger-- a 4oz. serving has 31% of the daily value (DV) for protein.
Comparing the DVs for different proteins is a better way of comparing two products than grams of protein alone. Two foods may have the same amount of protein per serving, but very different DVs because of differences in their PDCAAS.