There has been a recent surge of interest in the use of food-grade nanoparticles (NPs) for stabilizing food foams and emulsions. Cereal proteins are a promising raw material class to produce such NPs. Studies thus far have focused mostly on wheat gliadin and maize zein-based NPs. The former are effective interfacial stabilizing agents, while the latter due to their high hydrophobicity generally result in poor interfacial stability. Several strategies to modify the surface properties of wheat gliadin and maize zein NPs have been followed. In many instances, this resulted in improved foam or emulsion stability. Nonetheless, future efforts should be undertaken to gain fundamental insights in the interfacial behavior of NPs, to further explore NP surface modification strategies, and to validate the use of NPs in actual food systems.

A novel composite foam was prepared from native cassava starch and water hyacinth (WH) by baking in a hot mold. The effects of WH powder content (0, 3, 5, 7 or 10 wt%, dry starch basis) on the properties of the starch foam were investigated. A starch foam formulation with 5 wt% WH powder exhibited the highest flexural stress at maximum load (3.42 MPa), the highest flexural strain (extension) at maximum load (3.52%), the highest modulus (232.00 MPa), the lowest moisture content (6.77%) and the most uniform cell size distribution (0.44 ± 0.09 mm). Moreover, mechanical properties of starch foam with 5 wt% WH powder were better than the same properties of some commercial foams. After being coated with beeswax, the starch foams retained their shape after immersion in distilled water and their water solubility was significantly reduced. Results indicated that a starch foam/5 wt% WH composite with beeswax coating was a biodegradable foam that could possibly replace commercial non-degradable foam.

We designed Air-in-Oil-in-Water (A/O/W) emulsions. First, Air-in-Oil foams were fabricated by whipping anhydrous milk fat. The maximum overrun was obtained at 20 °C. The foams contained 30–35 vol% air and were stabilized solely by fat crystals. To refine the bubble size, foams were further sheared in a Couette’s cell. The average bubble size reached a value as small as 6.5 μm at a shear rate of 5250 s−1. The nonaqueous foams were then dispersed in a viscous aqueous phase containing sodium caseinate to obtain A/O/W emulsions. The shear rate was varied from 1000 to 7500 s−1, allowing to obtain Air-in-Oil globules whose average diameter ranged from 15 to 60 μm. To avoid globule creaming, the aqueous phase was gelled by incorporating hydroxyethyl cellulose. Homogeneous emulsions were obtained with fat globules containing around 22 vol% of residual air. The systems were kinetically stable for at least 3 weeks at 4 °C.

The relationship between structural and foaming properties of two tryptic and two peptic wheat gluten hydrolysates was studied at different pH conditions. The impact of pH on foam stability (FS) of the samples heavily depended on the peptidase used and the degree of hydrolysis reached. Surface dilatational moduli were in most, but not all, instances related to FS, implying that, although the formation of a viscoelastic protein hydrolysate film is certainly important, this is not the only phenomenon that determines FS. In contrast to what might be expected, surface charge was not a major factor contributing to FS, except when close to the point-of-zero-charge. Surface hydrophobicity and intrinsic fluorescence measurements suggested that changes in protein conformation take place when the pH is varied, which can in turn influence foaming. Finally, hydrolyzed gluten proteins formed relatively large particles, suggesting that protein hydrolysate aggregation probably influences its foaming properties.