Comparative studies on the peptide release, intestinal flora and metabolites changes of β-lactoglobulin- galactooligosaccharides/maltose conjugates during in vivo digestion

High-resolution mass spectrometry, 16S rDNA sequencing method and non-targeted metabolomics were performed to comparative study the peptide release, intestinal flora and metabolites changes of the β-lactoglobulin (BLG) - galactooligosaccharides (GOS)/maltose (Mal) conjugates during in vivo digestion. BLG-Mal and BLG-GOS conjugates exhibited gastric resistance, and the distribution of intestinal peptides (<3 kDa) gradually increased compared with BLG, which predominantly short fragments under 5 amino acids. BLG-GOS and BLG-Mal improved the diversity and structural composition of intestinal flora and changed short-chain fatty acids (SCFAs) content. Meanwhile, they also activated glycerophospholipid metabolic pathway, tyrosine, arginine and proline metabolic pathway. GOS with a large molecular weight, different carbon chains and prebiotic effects exerted a great influence on the peptide release, intestinal flora and metabolic pathway. Therefore, glycoprotein with long carbon chains significantly affected the peptide release, regulated the intestinal flora and SCFAs levels, and activated the metabolic pathways such as proline and tyrosine, improving intestinal health.