Interactions lipids-proteins during in vitro digestibility of oilseeds

Background: The limited resources and the ecological impact of animal protein production have led to a rise of plant-based diets. Face to an ever-increasing global demographic growth, the demand for protein products is expected to grow in the next decade, making the search for new protein sources essential. The oilseed proteins, generally present into the animal feed market, could have a potential application in Human nutrition. They offer a double nutritional interest in providing proteins and lipids. However, the nutritional quality of oilseed proteins and the impact of the lipids on their digestibility are not well-known.

Aim: The aim of this study was to determine the in vitro oilseed proteins digestibility and to assess the effect of lipids on protein digestibility according to the sourcing of plant proteins, processing method and nutrient composition of oilseed matrices.

Methods: The INFOGEST protocol was applied to determine the in vitro digestibility of the different formulas: flour and concentrate of sunflower and rapeseed with or without rapeseed oil. Pea was used as reference. In vitro digestates were characterized calculate the degree of protein and lipid hydrolysis.

Results: The addition of lipids in the reaction medium significantly influenced the in vitro digestibility of proteins from oilseeds, according to the nature of plant-based protein matrices (-15% in average for the flour and +10% in average for the concentrates). Similarly, in vitro lipid digestibility is affected by the presence of proteins, depending on the intrinsic lipid content in the protein matrix.

Conclusion: This study has shown that protein digestibility can be modulated by the presence of lipids, and reciprocally, proteins can have a notable effect on the degree of lipolysis. In addition, the extent of hydrolysis depends on the type protein, the matrix composition and the processing method. The combination of lipids with plant proteins could be a nutritional strategy to improve the essential amino acid bioavailability score of oilseed proteins.