Dextran-induced depletion flocculation in oil-in-water emulsions in the presence of sucrose

Fabrication and Stability Improvement of Monoglyceride Oleogel/Polyglycerol Polyricinoleate-Stabilized W/O High Internal Phase Pickering Emulsions

To decrease the lipid content in water-in-oil (W/O) emulsions, high internal phase Pickering W/O emulsions (HIPPE) were fabricated using magnetic stirring using a combination of monoglyceride (MAG) oleogel and polyglycerol polyacrylate oleate (PGPR) as stabilizers. Effects of MAGs (glyceryl monostearate-GMS, glycerol monolaurate-GML and glycerol monocaprylate-GMC) and internal phase components on the formation and properties of HIPPEs were investigated. The results showed that milky-white stabilized W/O HIPPE with up to 85 wt% aqueous phase content was successfully prepared, and the droplet interfaces presented a network of MAG crystals, independent of the MAG type. All HIPPEs exhibited great stability under freeze-thaw cycles but were less plastic. Meanwhile, GML-oleogel-based HIPPEs had larger particle size and were less thermal stable than GMS and GMC-based HIPPEs. Compared to guar gum, the internal phase components of sodium chloride and sucrose were more effective in reducing the particle size of HIPPEs, improving their stability and plasticity, and stabilizing them during 100-day storage. HIPPEs presented great spreadability, ductility and plasticity after whipping treatment. This knowledge provides a new perspective on the use of oleogels as co-stabilizers for the formation of W/O HIPPEs, which can be used as a potential substitute for creams.

Functional characteristics and microbiological viability of foam-mat dried Bambara groundnut (Vigna subterranea) yogurt from reconstituted Bambara groundnut milk powder

The functional, nutritional, and physical characteristics of foam-mat dried Bambara groundnut (Vigna subterranea) yogurt were investigated. Bambara groundnut powdered yogurt (BGNPY) was produced using Bambara groundnut milk powder (BGNMP) and Bambara groundnut milk (BGNM). BGNMP was reconstituted with water (1:5). The reconstituted BGN milk (BGNM-R) and original nonreconstituted BGNM (BGNM-NR) were inoculated with normal yogurt culture while held at a temperature of 45°C and incubated for 24 hr at 35°C. The BGN yogurts were dried employing the foam-mat drying process with gum arabic (6%) and methylcellulose (0.5%) as foaming agents and dried at 50°C for 24 hr. The BGN powdered yogurt from reconstituted milk (BGNPY-RM) and BGN powdered yogurt from nonreconstituted milk (BGNPY-NRM) were evaluated for functional, nutritional, thermal, and physical characteristics. Water absorption (1.27 and 1.31 g/g) and water solubility (73.3. and 71.22 100/g) index of the powdered yogurts did not differ significantly, while a significant (p < 0.05) difference was observed for the Tg of BGNPY-R and BGNPY-NR. Nutrient composition of BGNPY-R and BGNPY-NR had no significant (p > 0.05) difference, while ash differed significantly (p < 0.05). Particle size and particle size distribution of BGNPY-R and BGNPY-NR had no significant (p > 0.05) difference. Probiotic viability of BGNPY-R (7.2 log cfu/ml) remained above the minimum recommended dosage (6 log cfu/ml).

Application of Microrheology in Food Science

Microrheology provides a technique to probe the local viscoelastic properties and dynamics of soft materials at the microscopic level by observing the motion of tracer particles embedded within them. It is divided into passive and active microrheology according to the force exerted on the embedded particles. Particles are driven by thermal fluctuations in passive microrheology, and the linear viscoelasticity of samples can be obtained on the basis of the generalized Stokes-Einstein equation. In active microrheology, tracer particles are controlled by external forces, and measurements can be extended to the nonlinear regime. Microrheology techniques have many advantages such as the need for only small sample amounts and a wider measurable frequency range. In particular, microrheology is able to examine the spatial heterogeneity of samples at the microlevel, which is not possible using traditional rheology. Therefore, microrheology has considerable potential for studying the local mechanical properties and dynamics of soft matter, particularly complex fluids, including solutions, dispersions, and other colloidal systems. Food products such as emulsions, foams, or gels are complex fluids with multiple ingredients and phases. Their macroscopic properties, such as stability and texture, are closely related to the structure and mechanical properties at the microlevel. In this article, the basic principles and methods of microrheology are reviewed, and the latest developments and achievements of microrheology in the field of food science are presented.

Self-assembly in monoelaidin aqueous dispersions: direct vesicles to cubosomes transition

BACKGROUND

In the present study, synchrotron small-angle X-ray scattering (SAXS) and Cryo-TEM were used to characterize the temperature-induced structural transitions of monoelaidin (ME) aqueous dispersion in the presence of the polymeric stabilizer F127. We prove that the direct transition from vesicles to cubosomes by heating this dispersion is possible. The obtained results were compared with the fully hydrated bulk ME phase.

METHODOLOGY/PRINCIPAL FINDINGS

Our results indicate the formation of ME dispersion, which is less stable than that based on the congener monoolein (MO). In addition, the temperature-dependence behavior significantly differs from the fully hydrated bulk phase. SAXS findings indicate a direct L(alpha)-V(2) internal transition in the dispersion. While the transition temperature is conserved in the dispersion, the formed cubosomes with internal Im3m symmetry clearly contain more water and this ordered interior is retained over a wider temperature range as compared to its fully hydrated bulk system. At 25 degrees C, Cryo-TEM observations reveal the formation of most likely closely packed onion-like vesicles. Above the lamellar to non-lamellar phase transition at 65 degrees C, flattened cubosomes with an internal nanostructure are observed. However, they have only arbitrary shapes and thus, their morphology is significantly different from that of the well-shaped analogous MO cubosome and hexosome particles.

CONCLUSIONS/SIGNIFICANCE

Our study reveals a direct liposomes-cubosomes transition in ME dispersion. The obtained results suggest that the polymeric stabilizer F127 especially plays a significant role in the membrane fusion processes. F127 incorporates in considerable amount into the internal nanostructure and leads to the formation of a highly swollen Im3m phase.