RESUMO
Quality control of protein supplements intended for a large audience of consumers such as sportspeople is particularly important. A case study on quality control of dietary supplements containing protein and protein components is presented. The objective of the study was to evaluate the conformity of the quantities of amino acids, essential and branched-chain amino acids, declared on the label through measurements with chromatographic analytical tools. 16 sportspeople supplements from different European countries were tested. Analysis of concentrated whey protein highlighted some differences between the label and what was experimentally determined; in these samples some amino acids (6 amino acids out of 19) exceeded the maximum tolerance (>20%) regulated by the European Commission. To a lesser extent, analysis of the other classes revealed amino acid concentrations that exceeded the maximum analytical tolerance percentage. As regards the essential and branched amino acid supplements, it was seen that the declared quantity conforms with that determined experimentally.