Survival of intact bovine whey proteins across in vivo and simulated static in vitro models of the adult gastrointestinal tract

Bovine whey contains bioactive proteins that could benefit consumer health, but their intact bioactivity depends on their ability to survive the digestive process and remain intact to their sites of action. Our study assessed whey protein degradation in the adult human jejunum after whey protein isolate ingestion and during static in vitro gastric and intestinal digestions, using LC-MS/MS-based proteomics and SDS-PAGE. We found that 53 % of the protein counts identified in the gastric digesta, including β-lactoglobulin and lactoferrin were stable under simulated gastric conditions. However, most proteins were degraded during both in vitro and in vivo intestinal digestion. The intact protein survival profiles were closely aligned between in vitro and in vivo digestion samples. Understanding the survival of specific whey proteins during digestion will help determine their biological relevancy in their intact forms within the gastrointestinal tract and may inspire strategies to enhance their stability for specific functions.