Abstract
Major health and environmental concerns have developed for several years to promote the emergence of diets aiming at increasing plant proteins to reduce the consumption of animal resources. However, the transition towards more environmentally diets is hampered by the poor acceptance of vegan foods by Western consumers. Mixed animal/vegetable alternatives offer a new field of innovation to produce functional, multi-source, protein-rich food products. Plant proteins such as pea protein, while nutritionally interesting, can be difficult to use in food systems due to their low solubility and undesirable taste. This thesis proposed alternatives for the use of these proteins by reacting soluble pea proteins with casein micelles. These dairy protein colloids have unique structural properties that allow them to interact with soluble proteins after the application of a heat treatment, and thus improve their gelling properties. The challenge of this thesis was to work with a non-purified commercial isolate to minimize the energy costs of purification and to propose alternatives that could be easily applied at an industrial scale. The steps of the project allowed to find the ideal formulation conditions (total protein concentration of 4 % (w/w) with a ratio of 2.5/7.5 in pea/casein pellet) and the optimal technological pathway to generate mixed aggregates at the origin of homogeneous yoghurt-like acid gels with optimized structural and functional properties.The dynamic study of the association of pea proteins and casein micelles by a targeted multiscale approach allowed an in-depth characterization of the soluble pea proteins and their aggregates formed in terms of size, morphology, composition and nature of interactions which were found to be of low energy in contrast to those generated by the thermal treatment of soluble milk proteins. Interesting mechanical and textural properties were obtained for the acid gels with a stiffness and firmness 1.4 and 1.9 times higher for the pea protein and casein micelle mixtures compared to conventional casein micelle and serum protein gels, respectively.Moreover, the application of the high dynamic pressure process on soluble pea proteins upstream of gelation allowed a 35% reduction in the particle size of pea proteins, providing a solution to the size variability existing in commercial isolates and thus proposing the production of homogeneous acidic mixed gels.This project demonstrated that soluble commercial pea proteins are interesting protein resources for the formulation of gel-type protein matrices and that the hybrid aggregates obtained can, depending on the processes used and their order of sequencing, generate new gelled matrices increasing the proportion of vegetable proteins in dairy products.