Bridging the Gap: Techno-functional and nutritional evaluation of rapeseed and legume proteins for dairy alternatives

• Rapeseed protein matches pea, faba bean, and lentil in protein level • RPI meets FAO 2013 amino acid needs, legumes lack sulfur amino acids • PBMAs had higher protein than commercial ones, similar to cow’s milk • PBMAs showed high digestibility, with lowest DIAAS in sulfur amino acids Plant-based dairy alternatives provide many benefits, especially regarding sustainability and animal welfare. This has increased the demand for plant-based milk alternatives (PBMA), making it an interesting area for research and industry. Many PBMAs are currently less nutritious than dairy milk, particularly due to their low protein content. This study initially examined the nutritional composition, including amino acid profiles and techno-functional properties such as pH, total titratable acidity, protein solubility, water and oil holding capacity, colour and foaming behaviour of protein isolates derived from pea (PPI), faba bean (FPI), lentil (LPI), and rapeseed (RPI). A PBMA that mimics low-sugar, semi-skimmed dairy milk was produced using the above-mentioned protein ingredients. The PBMA was standardised to contain 3.5% (w/w) protein, 1.5% (w/w) fat, and 1.9% (w/w) sugar. The resulting PBMAs were characterised by analysing their amino acid profiles, protein quality based on in vitro protein digestibility, sugar, and fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) content. Techno-functional properties such as physical stability, rheological behaviour, foaming, and colour were also investigated. Despite RPI's more favourable amino acid profile, the resulting RPI milk alternative (MA) was challenging regarding its physical stability due to sedimentation and creaming. The legume-based MAs, PPI-MA, FPI-MA, and LPI-MA, exhibited strong functional characteristics, including physical stability and an apparent viscosity comparable to that of dairy milk. Additionally, their protein content matches that of cow's milk. While the obtained in vitro protein digestibility shows promising preliminary values, in vivo methods, such as human and pig trials, are considered the gold standard for digestion studies, and remain necessary for definitive assessment of the protein quality.