RESUMEN
Curcumin, a vital bioactive compound found naturally, has diverse biological applications. However, a major limitation of curcumin is its low bioavailability caused by its limited solubility in water. Hence, it is possible to overcome this problem through preparing oil in water nanodispersion of curcumin that emulsifier can play key role to produce nanodispersion. In the present study, the effect of three emulsifiers of Tween 80, Arabic Gum and Polyethylene glycol on preparing nanodispersions with desirable properties was investigated using subcritical water method and a mixture design. Zeta-potential and particle size of the achieved nanodispersions were taken into account as outcome factors. The optimum values for emulsifiers of Tween 80, Arabic Gum and Polyethylene glycol were obtained as 0.588 g, 0.639 g and 0.273 g, respectively, using the suggested model, so that obtained nanodispersion had minimum particle size (101.89 nm) and maximum zeta-potential (-24.99 mV). In fact, 102.5 nm and - 24.7 mV were obtained from experimental data at these values of emulsifiers. In addition, maximum loading potential (0.199 g/L), efficiency (99.5%), and minimum total curcumin loss (0.5%) were acquired at these optimum values. The results also show that the nanodispersion had a powerful antioxidant activity (65.27%) with extra antibacterial activity in facing with both E. coli and S. aureus strains. Moreover, curcumin nanodispersion was significantly taken up by HT-29 cells and resulted in the production of oxidative stress in the cells, leading to a decrease in the growth of cancer cells.
RESUMEN
The relationship between the composition and structure of food emulsions was evaluated from the effect of a mixture of emulsifiers Whey protein (WPI) - Tween 80 (T80) and the oil phase features, such as chain length and unsaturation degree (sunflower oil, a long chain triacylglycerol - LCT or NEOBEE® 1053, a medium chain triacylglycerol - MCT). Emulsions with LCT showed higher droplet size than MCT as a consequence of its higher viscosity. All emulsions exhibited shear thinning behavior, but the viscosity was influenced by their interface composition. An occurrence of the destabilization mechanism by creaming was observed in turbidimetric measurements, but no visual phase separation could be observed, indicating a good kinetic stability after a 7-day storage. The initial interfacial tension of the water-LCT or water-MCT oil was about 25â¯mN/m, but the WPI addition (1% w/w) reduced the initial interfacial tension to approximately 20â¯mN/m. The increase of T80 concentration led to a decrease of the interfacial tension, reaching a value around 10â¯mN/m in systems with pure T80. The curves of interfacial tension of systems with LCT or MCT showed differences in the decay rate of tension over time. These differences were attributed to characteristics of the oil phase (hydrophobicity, unsaturation degree, presence of impurities) and the different proportions of each emulsifier within the mixture of emulsifiers. Finally, a higher viscoelastic interface was observed in LCT emulsions, which were mainly stabilized by WPI molecules. Such molecules presented a higher resistance to the displacement due to the competitive adsorption phenomenon, since the LCT is a more hydrophobic oil. On the other hand, the interface with MCT and a higher T80 concentration was less viscoelastic due to an easier displacement of WPI from the interface and the replacement by T80. The results indicate that T80 can be used in combination with WPI to produce emulsions with good stability and lower concentration of synthetic compounds. Lastly, the interfacial layer composition is not only dependent on the WPI-T80 ratio in the bulk phase, but also on the oily phase features. These results provide a potential strategy for designing emulsified foods based on the choice of ingredients and knowledge of the interaction between them.