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This study investigated the characteristic and foaming properties of microgels derived from aquafaba, a byproduct generated during chickpea cooking processes. Two distinct approaches were employed for microgel production: a top-down method involving the mechanical disintegration of aquafaba gels through household blending and subsequent high-pressure homogenization and a bottom-up method incorporating an additional shearing step during the gelation of aquafaba. The resulting microgels, when spray-dried, exhibited a raisin-like morphology. Upon rehydration, particle size measurements indicated a prevalence of large microgel particles (D[4,3] values of 16, 10 ± 1, 27 and 13, 70 ± 3, 96 µm for top-down and bottom-up methods, respectively). Fourier transform infrared spectroscopy analysis revealed increased starch crystallinity in microgels produced via the top-down method. At the same time, no significant differences in protein secondary structures were observed between aquafaba powder and microgels. Despite similar particle sizes and structural changes, the impact of the foaming agent type (aquafaba powder vs. microgels) and whipping time on foam properties were demonstrated. Notably, aquafaba microgels resulted in higher foam overrun values (between 709.40 and 962.90%) than those reported in the literature, surpassing traditional protein sources such as egg white and whey protein. However, regarding foam stability, aquafaba powder samples outperformed microgels produced through both top-down and bottom-up methods, regardless of whipping time. The introduction of an ultrasonic bath treatment was found to be necessary to enhance the foam stability of microgel suspensions. To further optimize foaming properties and justify the additional cost associated with microgel production, future research should focus on understanding the adsorption mechanisms of aquafaba microgels at the air–water interface. This investigation will contribute valuable insights into improving foaming characteristics, making aquafaba microgels a promising alternative for various food applications. [ABSTRACT FROM AUTHOR]

Foamability and foam stability of dairy-based emulsions, as a function of emulsion droplet size ranging from micron- to nanometre-scale, were investigated. Fat phase (10 % w/ w of anhydrous milk fat, stearin or olein fraction) was mixed with 2 % w/ w protein solution (sodium caseinate or whey protein concentrate) and homogenised at 3, 10 and 35 MPa to obtain emulsions having particle sizes of about 1.20, 0.60 and 0.20 μm, respectively. The emulsions were cooled down and aged at 4 °C for 48 h to promote crystallisation. No fat coalescence was observed in any of the emulsions, as particle size distribution remained the same upon aging and whipping. It was shown that the smaller the particle size, the higher was the apparent viscosity and the lower was the solid fat content. Higher solid fat content tended to yield better foamability and foam stability. Destabilisation of air cells happened fastest with nanosized fat particles, resulting in shorter half-life of foam. [ABSTRACT FROM AUTHOR]