Impact of process conditions and type of plant protein on aggregate formation with whey protein and resulting ricotta-like gel texture

Aim of the study was to investigate the effect of process conditions and type of plant protein on protein aggregation and texture of hybrid ricotta alternatives. Four different plant proteins (soy, pea, lupin, potato) were used and first underwent a pre-treatment to increase solubility, followed by thermally-induced pre-aggregation of the hybrid systems with β-lactoglobulin-rich whey protein at varying pH and temperature. Aggregates were analysed via particle size distribution and SDS-PAGE. For production of the ricotta alternative, acidification and subsequent thermal coagulation formed the protein gel network. Texture analysis and visual evaluation of macroscopic structure was carried out. Results showed that aggregate size significantly affects gel strength. For soy-whey mixtures pH during pre-aggregation was the main factor affecting aggregate size, with a favourable diameter of 5 μm and a corresponding gel strength to whey-based ricotta of 0.9 N. Pea protein generally behaved similar to soy protein due to the similarity in protein composition and structure. In contrast, use of lupin resulted in a weaker gel, due lupin’s dense molecular structure and high denaturation temperature. Potato-whey hybrid systems formed large insoluble aggregates, which as a consequence did not contribute to gel formation. In summary, the results of the present study show that a variation of the protein type in hybrid ricotta alternatives requires process adaptations, but at the same time allows the creation of new gel structures for hybrid cheese alternatives. • pH governs size during protein aggregate formation. • effect of temperature was most pronounced when using pea protein. • aggregate size can be either too small or too large for strong gel network formation. • through optimisation of process and formulation ricotta-like texture may be achieved.