Neutrons and Food 8 at MLZ

Foam is critical in achieving satisfactory consumer perception for many food products, e.g. cappuccino-style beverages. Plant-based milks are increasingly used as dairy alternatives, but they often fail to match the foamability and stability of their dairy rivals, with substantial variation across plant sources. Our previous study has revealed notable differences among plant-based and dairy milks in foaming properties due to the variation in their composition and total solid content, as well as the interfacial adsorption characteristics of plant proteins.
Here we systematically characterized foam microstructure, destabilisation and liquid drainage of foams generated from dairy and plant-based milks using time-resolved SANS. The aqueous phase has been controlled at different H2O/D2O contrasts to isolate scattering contributions from air, protein, polysaccharide, and dispersed oil. It showed that different foam structures and stability among dairy and plant-based milks are associated with protein properties (including protein structure and interfacial adsorption kinetics), protein concentration, the type and concentration of hydrocolloids (including polysaccharides), and the presence of insoluble particles. Insoluble particles contribute to foam stability by causing congestion in the Plateau borders, as shown in the film thickness and liquid drainage data. These results highlighted the distinct mechanisms of foam stabilisation/destabilisation in dairy and plant-based milks.