Effect of pH and Pea Protein: Xanthan Gum Ratio on Emulsions with High Oil Content and High Internal Phase Emulsion Formation.

Electrostatic interaction between protein and polysaccharides could influence structured liquid oil stability when emulsification is used for this purpose. The objective of this work was to structure sunflower oil forming emulsions and High Internal Phase Emulsions (HIPEs) using pea protein (PP) and xanthan gum (XG) as a stabilizer, promoting or not their electrostatic attraction. The 60/40 oil-in-water emulsions were made varying the pH (3, 5, and 7) and PP:XG ratio (4:1, 8:1, and 12:1). To form HIPEs, samples were oven-dried and homogenized. The higher the pH, the smaller the droplet size (Emulsions: 15.60-43.96 µm and HIPEs: 8.74-20.38 µm) and the oil release after 9 weeks of storage at 5 °C and 25 °C (oil loss < 8%). All systems had weak gel-like behavior, however, the values of viscoelastic properties (G' and G″) increased with the increment of PP:XG ratio. Stable emulsions were obtained at pHs 5 and 7 in all PP:XG ratios, and at pH 3 in the ratio 4:1. Stable HIPEs were obtained at pH 7 in the ratios PP:XG 4:1, 8:1, and 12:1, and at pH 5 at PP:XG ratio 4:1. All these systems presented different characteristics that could be exploited for their application as fat substitutes.

Complexation of chitosan with gum Arabic, sodium alginate and κ-carrageenan: Effects of pH, polymer ratio and salt concentration.

The effects of pH, ionic strength and polymer ratio in the complexation of chitosan (CHI) with different anionic polysaccharides, namely gum Arabic (GA), sodium alginate (ALG) and κ-carrageenan (CRG), were investigated. This was made using titration techniques, which allowed the determination of stoichiometry and binding constant of complexes. The sulfated polysaccharide interacted more strongly with CHI than carboxylated polysaccharides. The increase of ionic strength (0-100 mM NaCl) in the polysaccharides complexation resulted in a significant reduction in the binding constant of GA:CHI and CRG:CHI, but did not influence the complexation of ALG with CHI. The pH and polymer ratio affected the formation and solubility of complexes GA:CHI, while for ALG:CHI and CRG:CHI, insoluble complexes were observed in all pH and polymer ratio evaluated. A phase transition of coacervate to gel was proposed to ALG:CHI and CRG:CHI, which can be related to the self-association of anionic polymers, when these are in excess.

Chitosan coated nanostructured lipid carriers (NLCs) for loading Vitamin D: A physical stability study.

A nanostructured lipid carrier (NLC) has been developed as a loading system for Vitamin D (VD). The NLCs were obtained by melt-emulsification method and coated with chitosan (CHI) by electrostatic deposition. The lipids used in the formulations were selected in order to provide higher encapsulation efficiency. Thermophysical properties of particles were evaluated by differential scanning calorimetry; particle stability was characterized by size distribution, polydispersity index, zeta-potential and light backscattering. The coating over NLCs was carried out by potentiometric titration with CHI at concentrations of 1.0, 1.5, 2.0 and 2.5% (w/v). Stearic (SA) and oleic acids (OA) were the lipids that showed higher compatibility with VD. The NLC 70(SA):30(OA) was the particle with the lowest polydispersity, size variation and less tendency to physical instability during the storage time. This formulation also presented encapsulation efficiency higher than 98%. In the particles coating, CHI adsorption into the colloidal dispersion provided an initial electrostatic stabilization of the system. A long-term steric barrier was established through further incorporation of CHI. Coated NLCs showed a core-shell structure and a positive zeta-potential (+30 mV), remaining stable for 60 days at 25 °C. During storage time, no expulsion of VD out of the particle was observed.

Comparison of microparticles produced with combinations of gelatin, chitosan and gum Arabic.

The complexation between proteins and/or polysaccharides has been studied during decades and despite the knowledge of how these interactions occur provides a basis for identifying the conditions of microparticle formation, the presence of the oil phase complicates the application of available theory to explain the complexation between polymers. In this work, we identified some parameters which can interfere with this interaction, highlighting the influence of molecular arrangements by modifying the combination of gelatin (GE) and gum Arabic (GA) including the chitosan (CHI), a comparatively stronger polycation, to form particles in the presence or not of an essential oil. The results indicated the influence of the polymeric system in the morphological structure of particles as well as in the capacity of oil retention. The encapsulation of oil was more efficient for systems containing GA, due to the ability of these systems to form complexes. However, GE-GA particles presented as multinucleous while CHI-GA as a mononucleous structure.