The digestibility of hydrothermally-treated bovine serum albumin glycated by glyoxal

The digestion of dietary advanced glycation end products (AGEs) largely determines their absorption in humans. To help elucidate the health effects of dietary AGEs, changes in the digestive behavior of bovine serum albumin (BSA, dietary protein) caused by glycation derived from glyoxal (GO, an important precursor of AGEs) in a simulated food heating system have been investigated. The hydrothermal aggregation of BSA was suppressed by GO derived glycation, generating glycated aggregates of loose and branched structures, according to dynamic light scattering (DLS), circular dichroism (CD) spectroscopy, free sulfhydryl group, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) results. Analysis of protein digests showed that glycation reduced the gastric and gastrointestinal digestibility of BSA and the bioavailability of all seven detected amino acids. A comparative analysis of the distribution of CML and lysine in glycated BSA digests with different molecular weights showed that carboxymethylation directly blocked the action of proteases on Lys residues.