Abstract
Background
Pea protein (from Pisum sativum) is under consideration as a sustainable, satiety-inducing food ingredient.
Objective
In the current study, pea-protein-induced physiological signals relevant to satiety were characterized in vitro via gastric digestion kinetics and in vivo by monitoring post-meal gastrointestinal hormonal responses in rats.
Design
Under in vitro simulated gastric conditions, the digestion of NUTRALYS® pea protein was compared to that of two dairy proteins, slow-digestible casein and fast-digestible whey. In vivo, blood glucose and gastrointestinal hormonal (insulin, ghrelin, cholecystokinin [CCK], glucagon-like peptide 1 [GLP-1], and peptide YY [PYY]) responses were monitored in nine male Wistar rats following isocaloric (11 kcal) meals containing 35 energy% of either NUTRALYS® pea protein, whey protein, or carbohydrate (non-protein).
Results
In vitro, pea protein transiently aggregated into particles, whereas casein formed a more enduring protein network and whey protein remained dissolved. Pea-protein particle size ranged from 50 to 500 µm, well below the 2 mm threshold for gastric retention in humans. In vivo, pea-protein and whey-protein meals induced comparable responses for CCK, GLP-1, and PYY, that is, the anorexigenic hormones. Pea protein induced weaker initial, but equal 3-h integrated ghrelin and insulin responses than whey protein, possibly due to the slower gastric breakdown of pea protein observed in vitro. Two hours after meals, CCK levels were more elevated in the case of protein meals compared to that of non-protein meals.
Conclusions
These results indicate that 1) pea protein transiently aggregates in the stomach and has an intermediately fast intestinal bioavailability in between that of whey and casein; 2) pea-protein- and dairy-protein-containing meals were comparably efficacious in triggering gastrointestinal satiety signals.
Acknowledgements
The authors wish to thank the biotechnicians at the Small Animal Centre (Wageningen University and Research Centre, The Netherlands), Arjan Schonewille, Elly Lucas, Carolien Vink (NIZO food research), and Alice von der Lieth (University of Copenhagen) for their essential contributions to the in vivo study and Saskia de Jong (NIZO food research) for expert assistance with the in vitro study.
JO directed the in vivo study and wrote/edited the general and in vivo study sections of the paper. TTL directed the in vitro study and wrote the in vitro study sections of the paper. All authors contributed to the conceptualization and design of the studies, and to the finalization of the manuscript.
Conflict of interest and funding
This work was supported by a project grant provided by Roquette Frères, the company that has developed and produces NUTRALYS® pea protein, the principal ingredient tested in this study. LG-D and DW are employed by Roquette Frères. JO and TLL were employed by NIZO food research, an independent contract research organization.