In vitro human gastrointestinal digestibility and colonic fermentation of edible yeast-based protein: A comparative...

The global protein demand is in constant increase requiring sustainable and healthier alternative proteins for animal and human nutrition. Yeast-based proteins (YBP) represent a non-negligible environmental-friendly fermentation-based solutions with high nutritional quality and bioavailability. Although in vitro studies cannot reflect the full complexity of in vivo digestion, it is considered as useful alternatives to animal models assessing protein digestibility. A 5 h TIM-1 digestion model (TNO Gastro-Intestinal Model) was used to assess the digestibility profile and amino acid bio-accessibility of YBP (3 separate production batches) versus whey and casein as references. Every hour, dialysate and ileal effluent samples were collected. Total nitrogen and free amino acid (FAA) were quantified. To assess the microbial impact, YBP digestate was subjected to 48 h Colon-on-a-Plate batch fermentation, after which the microbial composition by shotgun sequencing and microbial activity by Short-Chain Fatty Acids (SCFAs), Branched-Chain Fatty Acids (BCFAs) (GC-MS) and untargeted metabolomics (LA-REIMS) was analysed (from N = 11 healthy donors of faecal material). YBP, casein and whey were comparable in terms of digestibility. Although YBP showed a different metabolomic fingerprint compared to casein and whey, the microbial activity through SCFA quantification was significantly increased for all proteins compared to blank but not between protein sources. Whey and casein resulted in a higher abundance of Clostridium compared to YBP, while the treatment with YBP resulted in higher abundance of Bacteroides. Altogether, our results suggest that YBP could be a nutritionally relevant alternative protein.