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Background and Objectives: A protein-polysaccharide complex can be used to produce nanocapsules containing nutrients and active compounds. This study determined optimum conditions for producing caseinate-pectin based nanocomplexes containing omega-3 fatty acids with minimal particle size and size distribution and evaluated the stability and encapsulation efficiency of this system. Materials and Methods: Caseinate-pectin nanocapsules were formed by the addition of electrolyte salts into the caseinate solution (0.5%, 1%, 1.5%) containing omega-3 and pectin solution (0.2%, 0.45%, 0.7%) into the system. The pH was then adjusted to below the isoelecteric point of the protein. Determination of the size and size distribution was done using the laser light scattering method. Infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to detect complex formations and the types of interaction between the biopolymers and omega-3 and the thermal behavior of the complexes. Gas chromatography (GC) was used to determine the encapsulation of omega-3. A three-level four-factorial Box-Behnken experimental design was employed using Minitab 15 software to analyze particle size. Results: The complex containing 1% sodium caseinate and 0.45% pectin at pH = 4.1 had a the smallest particle size (86 nm) and turbidity with omega-3 capsulation, the particle size increased to 118 nm. FTIR results showed complex formation and interaction (electrostatic and hydrophobic) between the biopolymers and omega-3 and DSC results showed formation of new structures. Gas chromatography results showed an encapsulation efficiency of 12%-76% for the different formulations. Conclusions: The results showed that pH, pectin, and caseinate biopolymer concentrations played important roles on the particle size of the complex, stability, and encapsulation efficiency. This system can be used to encapsulate omega-3 in beverages having relatively acidic pH values. Keywords: Caseinate-pectin nanocomplex, Omega-3, DSC, FTIR, Encapsulation efficiency

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Background and Objectives: In addition to the numerous benefits of biopolymeric nanocomplex, it has drawbacks including difficulty in strict control of particle size and to prevent particle agglomeration. In this study, the influence of Tween 20 on the electrostatic interaction between sodium caseinate and gum Arabic was evaluated.

Materials and Methods: Initially, the organic phase (curcumin in ethanol) was introduced to aqueous phase (sodium caseinate, gum Arabic and Tween 20). Then by reducing the pH, the nanoparticles were formed. To evaluate the effects of the independent variables on the responses, the Box-Behnken design was used. The antioxidant activity of samples was evaluated by 1, 1diphenyl 2 picryl hydrazyl radical inhibition assay.

Results: Tween 20 has a significant effect on particle size, and particle size distribution (p<0/0001). Sodium caseinate and Tween 20 have significant effects on the encapsulation efficiency and antioxidant activity of curcumin nanocapsules (p<0/0001). Using desirability function, optimal processing conditions was achieved in the sodium caseinate concentration (0/28%), Arabic gum concentration (0/5469%), Tween 20 concentration (0/18%) and pH (5.02).

Conclusion: Due to the high encapsulation efficiency and antioxidant activity of curcumin nanocomplex and no need for high energy equipment such as homogenizer, this method is suggested as a simple, fast and low-energy technique.

Keywords: Curcumin, Nonionic surfactant, Protein/polysaccharide nanocomplex, Antioxidant activity

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Background and Objectives: Benefits of the effects of plant compounds with therapeutic characteristics depend on the bioavailability of their active ingredients. Curcumin includes limitations such as low stability and solubility as well as sensitivity to processing conditions and gastrointestinal conditions. Therefore, novel methods such as nanocomplex preparation in these compounds have been developed.
 Materials & Methods: To increase solubility and stability of curcumin, a curcumin-albumin nanocomplex was prepared. The response surface methodology-face cantered composite design statistical design was used to optimize three factors in preparation of nanoparticles. Factors included organic phase volume (6.4–11.11% v/v), pH (3–7) and curcumin ratio (5000–000 μg). Glutaraldehyde and tannic acid were used for crosslinking. Particle size, zeta potential (dynamic light scattering method), particle morphology (field emission-scanning electron microscopy, atomic force microscopy) and crosslinking index (ninhydrin and Fourier-transform infrared spectroscopy) were investigated. Factors and responses were analyzed using Design Expert Software v.8.
Results: In curcumin nanocomplex, the optimal conditions for the production of albumin nanoparticles were assessed at pH far from the isoelectric point of albumin and a volume proportion of the organic phase of 11.4%. For simultaneous achievement of the smallest particle with the highest curcumin encapsulation and desirability factor, the optimum efficiency was achieved at 3400 μg of curcumin. Curcumin encapsulation efficiency and particle size was 72.54%  and less than 230 nm, respectively. Use of tannic acid increased the efficiency of curcumin entrapment in albumin nanocomplex
(p < 0.05).
Conclusion: Results of this study showed that use of albumin-curcumin nanocomplex along with tannic acid as a crosslinking agent increased encapsulation and stability of curcumin.