Nutritional quality evaluation of commercial protein supplements

Protein supplements have received increasing attention by consumers over the last few decades. However, hundreds of them have recently exhibited irregularities including lower quantities of proteins than disclosed values. This study aimed to evaluate the nutritional quality of six commercial protein supplement powders (calcium caseinate, milk protein concentrate, egg white, pea protein isolate, whey protein concentrate and soy protein isolate). The chemical composition, amino acid content and in vitro digestibility were examined. Thus, calculate the amino acid scores corrected for amino acid and protein digestibility. In vitro digestion was also conducted and protein hydrolysis was monitored by SDS-page. Calcium caseinate powder and whey protein concentrate were only composed of proteinogenic amino acids and exhibited the highest essential amino acid content. As regards in vitro digestibility, these two supplements perfectly meet the quality expectations of the Food and Agricultural Organization (FAO). Conversely, the other four supplements exhibited a lower quality than the FAO reference protein. This was due to low digestibility (for egg white and milk concentrate) and/or lack of a specific essential amino acid (for milk concentrate and pea isolate).