Freeze drying and structure effects on in vitro protein digestion of some plant foods

Y. Reynaud (1) , M. Lopez (1) , Alain Riaublanc (2) , Isabelle Souchon (3) , Didier Dupont (4)

1 Improve SAS
2 BIA - Unité de recherche sur les Biopolymères, Interactions Assemblages
3 GMPA - Génie et Microbiologie des Procédés Alimentaires
4 STLO - Science et Technologie du Lait et de l'Oeuf

Introduction Plant proteins have recently gained attention in research and industrial areas by their relatively modest environmental, ethical and economic impact. Objective Food structure associated to food processing are known to generally impact sensitivity of proteins to digestive enzymes. Methodology Four plant-based foods produced from different protein sources (soy, pea or wheat) and offering different structure and their corresponding concentrate or isolate were digested following the INFOGEST protocol. Since tofu and seitan cannot be stored without structure degradation, the impact of freeze drying on protein digestion was also studied. Proteolysis progress was followed by monitoring the release of free amino-groups and proteolysis degree was assessed. Multi-scale characterization of foods was performed to allow data interpretation. Main findings Pea emulsion exhibited similar droplet size and lipid content than soymilk, only the protein source changed. Final proteolysis degree was higher with pea (60 %) than soy (45 %). When comparing the same source, protein digestion of tofu was more extensive than that of soymilk. This could be explained by differences in macrostructure since tofu is obtained through soy protein coagulation, but also by differences in the origin of beans. Indeed, proteolysis degrees at the end of the intestinal phase were different between protein isolates created from beans used for tofu vs soymilk (15 % vs 40 %). Proteins of tofu isolate were less hydrolyzed than tofu (15 % vs 26 %), that could be explained by different protein denaturation levels. Comparing a simple solubilization of commercial pea isolate with its emulsion with soy lipids, proteolysis was twice higher for the emulsion (60 % vs 30 %). Conclusion Ultimately, freeze-drying effect of protein digestion was highlighted for seitan, increasing final proteolysis rate from 9 % to 22 %, but not for tofu explained through enzymatic accessibility improved after freeze drying in the case of seitan.

Mots clés: protéolyse; plant protein; séchage au froid; protéine de plante

Mots clés: protéine végétale; allégations nutritionnelles et de santé; matrice alimentaire; émulsion alimentaire; digestion; procédé de séchage; modélisation multi échelle

Domaines: Alimentation et Nutrition; Ingénierie des aliments

Y. Reynaud, M. Lopez, Alain Riaublanc, Isabelle Souchon, Didier Dupont. Freeze drying and structure effects on in vitro protein digestion of some plant foods. 6.International Conference on Food Digestion, Apr 2019, Grenade, Spain. , 2019. ⟨hal-02100439⟩