[Bioavailability of amino acids from several industrially-prepared protein-containing products].
To evaluate the bioavailability of amino acids from proteins and protein-containing products, the area under the postprandial plasma-concentration-time-curve of the amino acids after oral administration needs to be calculated. Therefore, basic values depending on circadian plasma concentration rhythms have to be subtracted from measured values after loading. To determine the relative bioavailability of two tested samples, e.g., a protein-containing product before and after processing or two technologically different preparations of the same protein, it is sufficient to compare their absorption-curves, both corrected by the basic values. For that purpose the mean value-curves corresponding to the group of subjects are used, because the individual courses show considerable differences, in particular due to discontinuous gastric emptying. Enzymatic hydrolysis of a lactalbumin reduces the quantitative bioavailability of the amino acids by 12%. Concerning products used in nutrition of patients and babies, the availability from ready-to-drink liquid products is about 7-10% better than that out of the same dry products in powdered form. Compared with sterilization, ultrahigh heat treatment of milk protein products improves the availability slightly, by about 1%. Processing of dried green peas destined for use in convenience food increases the protein availability by 20%.