Effects of Storage Temperature, Atmosphere and Light on Chemical Stability of Astaxanthin Nanodispersions

Astaxanthin, as a functional lipid, can be incorporated easily into different water-based food formulations in the form of a nanodispersion. In this study, astaxanthin nanodispersions were produced using different stabilizer systems, namely, polysorbate 20 (PS20), sodium caseinate (SC), gum arabic (GA) and an optimum combination of these three stabilizers (OPT). Since astaxanthin is sensitive to oxidative damage, its degradations kinetics in the prepared nanodispersion systems were investigated as a function of storage temperature, atmosphere and light. The results showed that astaxanthin degradation followed a first-order kinetic and, in most cases, astaxanthin was more stable in optimum-formulated three-component-stabilized nanodispersions as compared to nanodispersion systems stabilized by individual stabilizers. In addition, high storage temperature and intense illumination significantly (P < 0.05) increased the degradation of astaxanthin, while oxygen-free conditions significantly (P < 0.05) reduced the astaxanthin degradation rate.     

Effect of processing conditions on physicochemical properties of astaxanthin nanodispersions

A top-down approach based on an emulsification–evaporation technique was used to prepare nanodispersions of astaxanthin. Response-surface methodology was employed to investigate the effect of the main processing conditions, namely, the applied pressure (20–90 MPa), number of cycles (0–4) and evaporation temperature (16–66 °C), on the average particle size, polydispersity index and astaxanthin concentration of the nanodispersions. Second-order polynomial regression models expressing the astaxanthin nanodispersion properties as functions of the main processing variables were significantly (p < 0.05) fitted, with high coefficient-of-determination values (R² > 0.90). A multiple-optimisation procedure showed that the optimum conditions of pressure, number of cycles of homogenization and evaporation temperature, were 50 MPa, two cycles and 47 °C, respectively. A statistical assessment showed insignificant (p > 0.05) differences between experimental and predicted values, thus verifying the adequacy of the final reduced models fitted for explaining the variation of emulsion properties, as a function of homogenization and evaporation conditions.     

Preparation of Nano-Emulsion-Based Hydrogels Conjugated Curcumin as Model Functional Lipid Bioactive Compound

The preparation of nanoemulsion-based alginate hydrogels, containing curcumin was the aim of current study. The nanoemulsions of coconut oil were prepared using solvent-displacement technique and then the obtained nanoemulsions were converted to hydrogels using the ion-gelling process. The effects of formulation parameters, namely, sodium alginate concentration (1–2 g L⁻¹), the weight ratio of calcium chloride to sodium alginate (2–4), and curcumin to sodium alginate (1–3), were also evaluated on swelling percentage, gel fraction, curcumin load, curcumin release, and antibacterial inhibitory zone of hydrogels. All studied characteristics were successfully correlated to the selected independent variables by second-order polynomial equations as models, with relatively high coefficients of determinations (R² > 86). According to multiple numerical optimization analysis, the most desired hydrogels can be obtained using 1.9 g L⁻¹ sodium alginate, curcumin/sodium alginate of 2.5 g g⁻¹, and calcium chloride/sodium alginate of 2.2 g g⁻¹, with the maximum swelling ratio (216%), gel fraction (29.9%), curcumin load (59.12%), antibacterial activity (clear-zone diameter of 5.27 cm), and the least curcumin release after 12 hours (87.75%). It was also resulted that the curcumin release from prepared optimum hydrogel obeys the first order kinetics. No significant differences between the measured and predicted data confirmed the suitability of suggested models.     

Preparation and characterization of α-tocopherol nanocapsules based on gum Arabic-stabilized nanoemulsions

Food Science and Biotechnology - The preparation of water dispersed α-tocopherol nanocapsules through solvent-displacement technique using gum Arabic (GA) as natural stabilizing and...