In vitro digestion evidence of how plant proteins modulate infant formulas digestibility

Infant formulas (IF) are the key nutritional source for infants who cannot be breastfed. There is currently a growing interest for these sensitive products, in order to control their quality and to design their composition with regard to nutritional balance and sustainable development concerns.This work aimed to study how plant proteins influence the digestibility of IF.Five infant formulas were developed with identical composition except that the protein source were whey proteins in the “reference IF”, pea, faba bean, rice or potato proteins in the four “plant IF” tested. The five IF were first evaluated using an in vitro static gastrointestinal model simulating infant conditions. Protein hydrolysis rate (PHR) and amino acid bioaccessibility (AAB) were measured using free amino group and free amino acid analyses, respectively. The pea and faba bean IF were then submitted to an in vitro dynamic digestion model closer to the physiological conditions, and compared to the reference IF. Protein digestibility (PHR and AAB) as well as the digesta microstructure were followed.Results showed that both PHR and AAB were very similar between the reference IF and pea and faba bean IF, but significantly lower for rice and potato IF. In dynamic conditions, the structure disintegration and the PHR showed differences among the reference, pea and faba bean IF. These differences were more pronounced during the gastric phase compared to the end of the intestinal digestion. This could result from the structure of proteins obtained from the processing steps that is known to influence the protein hydrolysis.This study provides new insights on the impact of protein source on the digestibility of IF. It especially showed that some plant proteins could be appropriate candidates for the composition of IF from a nutritional point of view