Dairy and plant based protein beverages: In vitro digestion behaviour and effect on intestinal barrier biomarkers

The consumer demand for protein-enriched food products continues to grow, in parallel with consumers' interest in plant based alternatives. The replacement of milk protein by plant protein is likely to be occur predominantly in prepared consumer foods such as nutritional beverages. This study aimed to compare and contrast powder beverages formulated with commercially available dairy versus plant ingredients in terms of protein digestion and gut barrier health. After simulated static in vitro gastrointestinal digestion, the release of free amino acids increased for all model beverages. In addition, the majority of peptides present in digested beverages were < 0.8 kDa in size. Gastrointestinal digestion did not increase the degree of protein hydrolysis in beverages formulated with prehydrolysed milk protein, whey or pea ingredients. A 2 h permeability assessment of digested beverages across the intestinal barrier, using Caco-2/HT-29/MTX co-cultures, revealed reduced transcription of tight junction protein 1, claudin-1 and mucus protein 2 albeit gut barrier impedance was unchanged. IL-8 mRNA levels in cell monolayers was significantly increased with digested fluids treatment but even more so with digesta from hydrolysed milk protein beverage. Overall, the response observed on intestinal biomarkers with digested plant beverages was similar to dairy based beverages supporting the replacement of dairy with plant proteins in powder beverage formulations.