Influence of Arabinan Fine Structure, Galacturonan Backbone Length, and Degree of Esterification on the Emulsifying Properties of Acid-Extracted Sugar Beet Pectins.

Sugar beet pectins (SBPs) are known for their emulsifying properties, but it is yet unknown which structural elements are most important for functionality. Recent results indicated that the arabinose content has a decisive influence, but the approach applied did not allow causality to be established. In this study, a mostly intact SBP was selectively modified and the obtained pectins were analyzed for their molecular structure and their emulsifying properties. De-esterification only resulted in a moderate increase in droplet size. The length of the pectin backbone only influenced the emulsifying properties when the homogalacturonan backbone was cleaved to a higher extent. By using different arabinan-modifying enzymes, it was demonstrated that both higher portions and chain lengths of arabinans positively influence the emulsifying properties of SBPs. Therefore, we were able to refine the structure-function relationships for acid-extracted SBPs, which can be used to optimize extraction conditions.

Texturing Fermented Emulsion Gels from Soy Protein: Influence of the Emulsifying Agent-Soy Protein vs. Pectin Microgels-On Gel Microstructure, Rheology and Tribology.

Soy-based yoghurt alternatives are nowadays preferred by consumers. However, they are often perceived as too firm or too soft, sandy, or fibrous. In order to improve this, fibres, especially as in form of microgel particles (MGP), and fats are added to the soy matrix to create a creamy mouthfeel. Both fat and pectin-based MGP can interact with each other and with the protein matrix, creating different microstructures. This can influence the rheological and tribological properties of plant-based protein gels. This works focuses on the effect droplet stabilisation (coconut oil) on the rheological and tribological behaviour of the fermented stirred soy protein gels. For this, fat droplets were stabilised with MGP, SPI, or a mixture of both. Whilst the rheological behaviour remained unchanged for all investigated samples, the tribology of the samples depended on the emulsifier used. The addition of fat decreased the traction coefficient compared to the reference samples without fat. Even though all samples had the same fat content and identical droplet sizes, differences were observed in their lubricating properties. Droplets stabilised solely with SPI presented the best lubricating properties, as indicated by the lowest traction coefficient. Samples stabilised with MGP (or in mixture with SPI) caused higher friction.

Effect of Conformation of Sugar Beet Pectin on the Interfacial and Emulsifying Properties.

The influence of the conformation of sugar beet pectin (SBP) on the interfacial and emulsifying properties was investigated. The colloidal properties of SBP, such as zeta potential and hydrodynamic diameter, were characterized at different pH levels. Furthermore, pendant drop tensiometry and quartz crystal microgravimetry were used to study adsorption behavior (adsorbed mass and adsorption rate) and stabilizing mechanism (layer thickness and interfacial tension). A more compact conformation resulted in a faster reduction of interfacial tension, higher adsorbed mass, and a thicker adsorption layer. In addition, emulsions were prepared at varying conditions (pH 3-5) and formulations (1-30 wt% MCT oil, 0.1-2 wt% SBP), and their droplet size distributions were measured. The smallest oil droplets could be stabilized at pH 3. However, significantly more pectin was required at pH 3 compared to pH 4 or 5 to sufficiently stabilize the oil droplets. Both phenomena were attributed to the more compact conformation of SBP at pH < pKa: On the one hand, pectins adsorbed faster and in greater quantity, forming a thicker interfacial layer. On the other hand, they covered less interfacial area per SBP molecule. Therefore, the SBP concentration must be chosen appropriately depending on the conformation.

Fabrication and characterization of double (W1/O/W2) emulsions loaded with bioactive peptide/polysaccharide complexes in the internal water (W1) phase for controllable release of bioactive peptide.

The objective of this study was to develop food-grade double emulsions containing bioactive peptide (BP)/polysaccharide (P) complexes and to investigate their thermal stability (e.g., BP release) at different temperatures. The BP/P complexes were formed via electrostatic interactions, and successfully encapsulated into the internal water phase of double emulsions with different oil phases. All emulsions clearly showed temperature dependence during storage. BP/P complex-loaded double emulsions showed higher thermal stability and lower release of encapsulated BP (45 °C: < 1%, 65 °C: < 30%) over time, which effectively prevented BP release within the emulsion system. For the effect of the oil phase, the BP released from double emulsions was in the order of MCT > coconut > canola oil. Thus, we concluded that BP release can be controlled in double emulsions by differently charged polysaccharides and oil types and that BP/P-loaded double emulsions can be utilized as functional ingredients for developing heat-sensitive food products.

Collagen peptide-loaded W1/O single emulsions and W1/O/W2 double emulsions: influence of collagen peptide and salt concentration, dispersed phase fraction and type of hydrophilic emulsifier on droplet stability and encapsulation efficiency.

Bioactive peptides hold great promise as functional ingredients, but they are susceptible to hydrolysis (e.g., protease degradation) during digestion and under different physiological conditions in the human body. Thus, bioactive peptides must be encapsulated first to preserve their innate characteristics and to ensure delivery to an absorption site at the small intestine without biodegradation. The objective of this study was to formulate stable single emulsions of water in oil (W1/O) and double emulsions of water in oil in water (W1/O/W2) containing collagen peptide as core material. In this study, the influence of the following parameters was investigated: collagen peptide concentration (0-20%), salt (0% or 1% NaCl), hydrophilic emulsifiers for the outer water phase (Tween 80, lecithin, chitosan, pectin), and the use of different inner/outer water fractions (20-50% inner water, 50-80% outer water) on the droplet stability of the W1/O and W1/O/W2 emulsions during storage. In particular, the influence of the osmolytes was investigated to evaluate the change in osmotic balance and destabilization of the W1/O/W2 emulsion system as the encapsulated peptide was also osmotically active. Tween 80-stabilized W1/O/W2 emulsions showed the best droplet stability without phase separation (d90,3 = 36.6 µm) and the highest collagen peptide retention (encapsulation efficiency > 90%). During prolonged storage, collagen peptides were released from the W1/O/W2 emulsion system without significant droplet size changes, possibly due to diffusion of the collagen peptide from the inner to the outer water phase. Therefore, our findings can be utilized for preparing stable functional foods or cosmetic products from W1/O/W2 emulsions containing bioactive ingredients.