Evaluation of the nutritional quality of yeast protein in comparison to animal and plant protein using growing rats and INFOGEST model

Yeast, identified as a microorganism, boasts a considerable protein content, positioning yeast protein as a highly promising alternative in the quest for sustainable protein sources. The primary aim of this study is to evaluate the protein quality of yeast protein and compare it with animal proteins (whey concentrate/isolate proteins) and plant proteins (soy, wheat, pea proteins). Notably, yeast protein exhibits the highest ratio of indispensable/dispensable amino acids (IAAs/DAAs, 0.91). However, in both in vivo and in vitro digestion experiments, yeast protein demonstrated lower true protein digestibility (TPD) and true ileal digestibility (TID) compared to other proteins. Despite this, the yeast protein's amino acid score (AAS, 1.37 for >3 years), protein digestibility-corrected amino acid score (PDCAAS, 100 % for >3 years), and digestibility-corrected amino acid score (DIAAS, 82.42 % for >3 years) of yeast protein surpassed those of plant proteins, yet remained lower than animal proteins primarily due to its lower digestibility.