Enzymatically modified quinoa starch-based Pickering emulsion: Effect of enzymolysis and emulsifying conditions

Both the effects of enzymolysis condition on the microstructures and emulsifying property of enzymatic modified quinoa starch (EMQS) and the effects of emulsion formulation on the EMQS based emulsions were investigated. The emulsifying capacity (EC) and stability (ES) of EMQS were positive correlated with enzyme amount (0-2.4 % w/w_starch). The particle sizes of EMQS decreased and its hydrophobicity increased with increasing enzyme amount (0-2.4 % w/w_starch), which were the main reasons for the increasing emulsifying performance of EMQS. With the increasing starch concentration, the EC of the EMQS increased, the oil droplet size of the emulsion decreased. With the oil/water ratios ranging from 1:9 to 6:4, the emulsification index (EI) and oil droplet size of the emulsion increased. EMQS based emulsion had a relatively good stability in the pH range of 2-10. This study lays the foundation for the application of EMQS as a stable clean-label Pickering emulsifier.

Formulation and stability of horse oil-in-water emulsion by HLB system

Optimal condition was determined to prepare horse oil-in-water (O/W) emulsion stabilized by different HLB system. Span 60 and Tween 60 were used to achieve the predetermined HLB values ranging from 10 to 14 and the surfactant concentrations were adjusted to 10-20%. Fifteen formulated O/W emulsions were characterized by mean particle diameter, zeta-potential (ZP), polydispersity index, and encapsulation efficiency (EE, %). Mean particle diameter decreased with increasing HLB value and surfactant concentration. Particles of the emulsion with HLB 12 and surfactant concentration at 15% were distributed in the size of below 500 nm. The particle diameter and EE (%) of the emulsion with HLB 11 or 12 and surfactant concentration at 15 or 20% were not significantly changed during storage at 40 °C for 15 days. These results suggest the characteristics of horse oil O/W emulsion are dependent on HLB values and surfactant concentration so that affect to emulsion properties during storage.

Development of preservative-free nanoparticles-based emulsions: Effects of NP surface properties and sterilization process

Model emulsions were developed with or without commercial titanium dioxide nanoparticles (NP) carrying various surface treatments in order to get close physicochemical properties whatever the NP surface polarity (hydrophilic and hydrophobic). Rheology and texturometry highlighted that the macroscopic properties of the three formulated emulsions were similar. However, characterizations by optical microscopy, static light scattering and zetametry showed that their microstructures reflected the diversity of the incorporated NP surface properties. In order to use these model emulsions as tools for biological evaluations of the NP in use, they had to show the lowest initial microbiological charge and, specifically for the NP-free emulsion, the lowest bactericidal effect. Hence, formulae were developed preservative-free and a thermal sterilization step was conducted. Efficiency of the sterilization and its impact on the emulsion integrity were monitored. Results highlighted the effect of the NP surface properties: only the control emulsion and the emulsion containing hydrophilic NP fulfilled both requirements. To ensure the usability of these model emulsions as tools to evaluate the 'NP effect' on representative bacteria of the skin microflora (S. aureus and P. fluorescens), impact on the bacterial growth was measured on voluntary inoculated formulae.